Takeoff and Landing Performance Optimization

Development of a Computional Methodology

João Pedro Rodrigues de Lemos Viana

Dissertation submitted to obtain the Master’s Degree in

Aerospace Engineering

Jury

Chair: Prof. Fernando José Parracho Lau Supervisor: Prof. António José Nobre Martins Aguiar External examiner: Prof. Pedro da Graça Tavares Alvares Serrão

October 2011

i

Acknowledgments

It is a pleasure to thank those who have contributed to the realization of this dissertation:

Daniela Vasco, my girlfriend, who has always supported me, especially in the later stages of

this work. Thank you for your patience.

António Aguiar, Engr., my supervisor, for giving me the chance to take part in such an

interesting project and, also, for the amount of time and close attention to detail he has always

offered when coordinating this project.

Carlos Figueiredo, one of the lead engineers on TAP’s Electronic Flight Bag project, who has

played a major role in this work, never hesitating in grating me some of his valuable time.

António Messias, Engr., Pedro Faria Pereira, Engr., and Paulo Marques, who provided utmost

important feedback during the development of this project.

Notwithstanding all the people that made my experience more enjoyable at TAP during the last

six months, namely Bruno Moreira, David Afonso, Marília Santos, Ana Maria Sousa, Amélia

Santos, Ivo Santos and Belinda Cardoso.

ii

Abstract

During the past decades the global aviation industry has been experiencing a precarious

balance between revenue and costs. Besides, the modern world is living an economic recession

and so crude prices are now higher than ever. Therefore, all over the world, airlines need to

adapt and evolve, finding new ways of struggling through the competitive world of commercial

aviation. Optimization is currently the key to succeed.

Aircraft performance data calculation and optimization reflects through the whole airline

operation. Besides having flight safety as its ultimate concern, data availability and easy

recalculation makes airlines’ operation more safeguarded to operation disruptions due to

external agents. Also, the quality of this data reflects in the airlines’ balance sheets at the end of

the year as the result of possible savings in different areas of operation [1].

The present work focuses in the development of a computational application for takeoff and

landing performance data generation and optimization. The takeoff performance optimization

entails the maximization of the Regulatory TakeOff Weight (RTOW) and the respective

operational speeds (V1, VR and V2). In a similar way, the Regulatory Landing Weight (RLW), the

final approach speed (VFA) and the landing distances (actual and required) are computed during

the landing optimization. The results are to be automatically published in the form of RTOW and

RLW charts. The actual calculations are processed by Airbus’ Operational and Certified TakeOff

and landing Performance Universal Software (OCTOPUS).

The developed application is more than a simple program; it handles a set of TAP’s databases

and external programs with the single objective of providing customized aircraft performance

optimization capabilities, at the distance of one click, to TAP’s personnel.

Keywords: Aircraft Performance; Performance Software; Takeoff Optimization; Landing

Optimization; OCTOPUS.

iii

Resumo

Ao longo das últimas décadas, o sector da aviação tem vivido num equilíbrio precário entre

receitas e despesas. A economia mundial está actualmente em recessão e os preços do

petróleo estão mais altos do que nunca. Tendo isto em conta, as companhias aéreas precisam

de se adaptar e evoluir, de modo a encontrar novas formas de vencerem no mundo competitivo

da aviação comercial. A optimização é, hoje, a chave para o sucesso.

O cálculo e optimização dos dados de desempenho aeronáutico reflectem-se através de toda a

cadeia de operação das companhias aéreas. Para além de ter a segurança do voo como

derradeiro objectivo, a disponibilização e fácil actualização destes dados torna as companhias

aéreas mais protegidas contra agentes externos. A qualidade dos mesmos reflecte-se no final

do ano, podendo reduzir as despesas em diversas áreas de operação [1].

O presente trabalho foca-se no desenvolvimento de uma aplicação computacional para

produção e optimização de dados de desempenho à descolagem e aterragem. A optimização

do desempenho à descolagem pressupõe a maximização do peso regulamentado à

descolagem (RTOW – Regulatory TakeOff Weight) e as respectivas velocidades operacionais

(V1, VR e V2). De forma semelhante, o peso máximo regulamentado à aterragem (RLW –

Regulatory Landing Weight), a velocidade final de aproximação (VFA) e as distâncias de

aterragem (concreta e necessária) são calculadas durante a optimização de aterragem. Os

resultados devem ser publicados sob a forma de tabelas de RTOW e RLW. Os cálculos por

detrás da optimização são efectuados por um programa oficial da Airbus – OCTOPUS

(Operational and Certified TakeOff and landing Universal Software).

A aplicação desenvolvida é mais do que um simples programa, lidando com diversas bases de

dados da TAP e interagindo com programas externos. O objectivo final do projecto é

proporcionar capacidades personalizadas de optimização de desempenho aeronáutico a

engenheiros e pilotos.

Palavras-chave: Desempenho Aeronáutico; Software de Desempenho; Optimização de

Descolagem; Optimização de Aterragem; OCTOPUS.

iv

Table of Contents

Acknowledgments ......................................................................................................................... 1

Abstract ......................................................................................................................................... 2

Resumo ......................................................................................................................................... 3

Table of Contents .......................................................................................................................... 4

List of Figures ................................................................................................................................ 6

List of Tables ................................................................................................................................. 8

List of Acronyms ............................................................................................................................ 9

1. Introduction ............................................................................................................................ 1

1.1 Economic Scenario........................................................................................................ 1

1.2 Relevance ...................................................................................................................... 2

1.3 Airlines’ Operational Context ......................................................................................... 2

1.4 Objectives ...................................................................................................................... 2

1.5 Dissertation Structure .................................................................................................... 3

2. TAP’s Case Study ................................................................................................................. 4

2.1 Flight Dispatch ............................................................................................................... 4

2.2 Flight Operations Engineering Department ................................................................... 4

2.3 Remarks ........................................................................................................................ 5

3. Aircraft Performance.............................................................................................................. 6

3.1. Aircraft Settings ............................................................................................................. 6

3.2. Aircraft Limitations ......................................................................................................... 9

4. Takeoff Performance ........................................................................................................... 16

4.1. Operational Speeds ..................................................................................................... 16

4.2. Runway ........................................................................................................................ 19

4.3. Obstacles and Takeoff Trajectory ............................................................................... 22

4.4. Outside Elements ........................................................................................................ 26

4.5. Limitation Summary ..................................................................................................... 28

5. Takeoff Optimization............................................................................................................ 30

5.1. Optimization Range ..................................................................................................... 30

5.2. Free Parameters Influence .......................................................................................... 31

5.3. Optimization Process................................................................................................... 34

5.4. Flexible Takeoff ........................................................................................................... 36

6. Landing Performance .......................................................................................................... 38

6.1. Operational Speeds ..................................................................................................... 38

6.2. Runway ........................................................................................................................ 39

6.3. Go-Around Requirements ........................................................................................... 42

v

6.4. Outside Elements ........................................................................................................ 43

6.5. Limitation Summary ..................................................................................................... 44

7. Takeoff and Landing Performance Application (TLP) ......................................................... 45

7.1. Structure ...................................................................................................................... 45

7.2. User Interface Overview .............................................................................................. 47

7.3. Databases and Internal Classes ................................................................................. 50

7.4. Relevant Routines ....................................................................................................... 50

7.5. OCTOPUS ................................................................................................................... 52

7.6. Testing and Validation ................................................................................................. 54

8. Conclusion ........................................................................................................................... 58

9. References ......................................................................................................................... 59

APPENDIX A – Regulation Transcripts ....................................................................................... 61

APPENDIX B – Performance on Wet and Contaminated Runways ........................................... 66

APPENDIX C – TLP .................................................................................................................... 70

APPENDIX D – FAJS-21R .......................................................................................................... 86

APPENDIX E – FM Page - A330-202 ......................................................................................... 90

APPENDIX F – Obstacles Limitation Verification ........................................................................ 91

APPENDIX G – PEP-FM Files .................................................................................................... 95

vi

List of Figures

Figure 1 - (a) Jet Fuel costs in the US. ......................................................................................... 1

Figure 1 - (b) Overall Airline Costs Mirroring Fuel Price Changes. ............................................... 1 Figure 2 - High-lift devices on an Airbus A340. ............................................................................. 6 Figure 3 - Simple (a) and fowler (b) trailing edge flaps. ................................................................ 6 Figure 4 - Slat. ............................................................................................................................... 7 Figure 5 - Flaps lever. ................................................................................................................... 7 Figure 6 - Environmental Control Systems for the A320 family. ................................................... 8 Figure 7 - CL versus angle of attack. .......................................................................................... 10 Figure 8 - VMCG. ........................................................................................................................... 10 Figure 9 - (a) Sideslip angle. ....................................................................................................... 11

Figure 9 - (b) in a one-engine-inoperative condition. .................................................................. 11 Figure 10 - VMU determination. .................................................................................................... 12 Figure 11 - Aircraft Weights. ........................................................................................................ 13 Figure 12 - A319-111 Environmental Envelope. ......................................................................... 14 Figure 13 - TOGA thrust versus OAT and PA for a given engine type. ...................................... 15 Figure 14 - Takeoff Profile. .......................................................................................................... 16 Figure 15 - Decision Speed. ........................................................................................................ 17 Figure 16 - Takeoff Speed Summary and Limitations related to V1, VR, VLOF and V2. ................ 18 Figure 17 - Stopway. ................................................................................................................... 19 Figure 18 - Clearway. .................................................................................................................. 19 Figure 19 - Available Takeoff Lengths. ....................................................................................... 20 Figure 20 - Lineup Adjustment, Top. ........................................................................................... 20 Figure 21 - Lineup Adjustment, Side. .......................................................................................... 20 Figure 22 - Runway slope effect on takeoff performance. .......................................................... 22 Figure 23 - Takeoff Path and Definition of Various Segments. ................................................... 23 Figure 24 - Gross and net takeoff paths. ..................................................................................... 24 Figure 25 - Departure Sector for track changes under 15°. ........................................................ 25 Figure 26 - Departure Sector for track changes over 15°. .......................................................... 25 Figure 27 - Headwind determination. .......................................................................................... 26 Figure 28 - Headwind effect on ground speed. ........................................................................... 27 Figure 29 - Pressure altitude effect on takeoff performance. ...................................................... 27 Figure 30 - Takeoff Performance Limitations. ............................................................................. 29 Figure 31 - Takeoff configurations performance.. ....................................................................... 32 Figure 32 - Runway Limited MTOW. ........................................................................................... 32 Figure 33 - (a) Effect of V2/VS in the obstacles, takeoff segments. ............................................. 33

Figure 33 - (b) Effect of V2/VS in the brake energy and tire speed limitations. ............................ 33 Figure 34 - Optimum V1/VR. ......................................................................................................... 33 Figure 35 - MTOW as function of V1/VR and V2/VS...................................................................... 35 Figure 36 - Range of soultions that maximize MTOW. ............................................................... 35 Figure 37 - Takeoff speeds calculation. ...................................................................................... 35 Figure 38 - Flexible temperature principle. .................................................................................. 36 Figure 39 - Obstacle influence on LDA. ...................................................................................... 39 Figure 40 - Actual Landing Distance. .......................................................................................... 39 Figure 41 - Airborne phase for an automatic landing. ................................................................. 40 Figure 42 - Ground role phase for an automatic landing. ........................................................... 40 Figure 43 - Go-around procedure................................................................................................ 43 Figure 44 - Pressure altitude influence in the landing performance............................................ 43 Figure 45 - TLP structure. ........................................................................................................... 45

vii

Figure 46 - “Please Wait” animated message running in an additional thread. .......................... 46 Figure 47 - TLP on startup. ......................................................................................................... 46 Figure 48 - Aircraft page for the Takeoff Optimization mode. ..................................................... 47 Figure 49 - Aircraft Failures form................................................................................................. 47 Figure 50 - Runway page for the Takeoff Optimization mode. ................................................... 48 Figure 51 - Options page for the Takeoff Optimization mode. .................................................... 48 Figure 52 - Calculation page for the Takeoff Optimization mode. ............................................... 49 Figure 53 - Temperature vector. .................................................................................................. 49 Figure 54 - TLP’s Output for the Takeoff Optimization mode. .................................................... 50 Figure 55 - Pressure Altitude function of Pressure. .................................................................... 51 Figure 56 - OCTOPUS Structure. ................................................................................................ 52 Figure 57 - OCTOPUS Functions................................................................................................ 53 Figure 58 - Aircraft braking coefficient for a 200 psi tire pressure on a wet runway. .................. 67 Figure 59 - Aircraft braking coefficient on a wet runway. ............................................................ 67 Figure 60 - Physics of contaminant drag. .................................................................................... 68 Figure 61 - Displacement Drag. .................................................................................................. 68 Figure 62 - Impingment Drag. ..................................................................................................... 68 Figure 63 - Hydroplaning effect. .................................................................................................. 69 Figure 64 - Effect of contaminants on takeoff distances. ............................................................ 69

viii

List of Tables

Table 1 - A320 family Flap and Slat configurations....................................................................... 7 Table 2 - A319-111 CDL. .............................................................................................................. 9 Table 3 - Thrust Setting and EGT Limit for an A340-312 (CFM56-5C3 engine). ........................ 15 Table 4 - Lineup Adjustments for 90° Runway Entry. ................................................................. 21 Table 5 - Takeoff Segments Characteristics. .............................................................................. 23 Table 6 - Minimum height to start a track change according to wingspan. ................................. 24 Table 7 - Semi-width ( E0) at the Start of the Departure Sector. ............................................ 26 Table 8 - Wet and contaminated runways. .................................................................................. 28 Table 9 - TAP’s takeoff limitations. .............................................................................................. 29 Table 10 - Influencing Parameters. ............................................................................................. 30 Table 11 - V2/VS maximum values for the Airbus family. ............................................................ 31 Table 12 - Influence of V2/VS ratio on takeoff limitations. ............................................................ 34 Table 13 - Minimum climb gradients during approach climb (OEI). ............................................ 42 Table 14 - Landing limitations. .................................................................................................... 44 Table 15 - Aircraft models and respective databases. ................................................................ 53 Table 16- TLP’s takeoff optimization results. .............................................................................. 55 Table 17 - Selected runways’ lengths. ........................................................................................ 55 Table 18 - AFM’s takeoff results.................................................................................................. 55 Table 19 - Optimum weights and ratios obtained by PEP’s TLO module. .................................. 56 Table 20 - TLP landing optimization results. ............................................................................... 56 Table 21 - Required Landing Distance calculated by FM’s Landing Distance function. ............. 57 Table 22 - ALD calculated by FM’s Operational Landing Distance function. .............................. 57 Table 23 - Maximum weight calculated by FM’s Landing Climb Gradient function. ................... 57 Table 24 - Maximum weight calculated by FM’s Approach Climb Gradient function. ................. 57

ix

List of Acronyms

ACARS – Aircraft Communication and Reporting System

ACG – Approach Climb Gradient

AEO – All Engines Operating

AFM – Aircraft Flight Manual

ALD – Actual Landing Distance

API – Application Interface

ASD – Accelerate-Stop Distance

ASDA – Accelerate Stop Distance Available

ATA – Air Transport Association of America

ATOW – Actual Takeoff Weight

CDL – Configuration Deviation List

CL – Climb

– Lift coefficient

CWY – Clearway

Da – Airborne Phase

DB – Database

Dg – Ground Phase

DOW – Dry Operating Weight

EASA – European Aviation Safety Agency

ECS – Environmental Control System

EFB – Electronic Flight Bag

EGT – Exhaust Gas Temperature

FAA – Federal Aviation Administration

FBW – Fly-By-Wire

FCOM – Flight Crew Operating Manual

HW – Headwind component

ICAO – International Civil Aviation Organization

ISA – International Standard Atmosphere

JAA – Joint Aviation Authority

LD – Landing Distance

LW – Landing Weight

MCT – Maximum Continuous Thrust

MEL – Minimum Equipment List

MEW – Manufacturer’s Empty Weight

MLW – Maximum Structural Landing Weight

MSL – Mean Sea Level

MTOW – Maximum Structural Takeoff Weight

OAT – Outside Air Temperature

OCTOPUS – Operational and Certified TakeOff and landing Performance Universal Software

OEI – One Engine Inoperative

OEW – Operational Empty Weight

OLE – Object Linking and Embedding

PEP – Performance Engineer’s Programs

QNH – Local mean sea level atmospheric pressure setting (Q-code system)

RLD – Required Landing Distance

RLW – Regulatory Landing Weight

RTO – Rejected Takeoff

RTOW – Regulatory Takeoff Weight

x

RWY – Runway

S – Aerodynamic reference wing area

SWY – Stopway

TAS – True Air Speed

TLO – Takeoff and Landing Optimization

TLP – Takeoff and Landing Performance Program

TOD – Takeoff Distance

TODA – Takeoff Distance Available

TOR – Takeoff Run

TORA – Takeoff Runway Available

TOGA – TakeOff-Go-Around

TOW – Takeoff Weight

TFlex – Flexible Temperature

TFlex Max – Maximum Flexible Temperature

TMAX – Maximum Operational Temperature

TREF – Reference Temperature (or flat rated temperature)

V – Airspeed

V1 – Decision Speed

V2 – Takeoff Climb Speed

VFA – Final Approach Speed

VEF – Engine Failure Speed

VLOF – Lift-off Speed

VLS – Lowest Selectable Speed

VMBE – Maximum Brake Energy Speed

VMCA – Minimum Control Speed in the Air

VMCG – Minimum Control Speed on the Ground

VMCL – Minimum Speed During Approach and Landing

VMU – Minimum Unstick Speed

VR – Rotation Speed

VREF – Reference Speed

VS – Stall Speed

VSR – Reference Stall Speed

VS1g – 1-g stall speed

VTD – Mean Touchdown Speed

VTIRE – Maximum Tire Speed

ZFW – Zero Fuel Weight

– Air density

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1

1. Introduction The present work was developed in close collaboration with TAP Portugal, the national airline of

Portugal. Operating almost 2,000 weekly flights through a route network that comprises 77

destinations in 34 countries worldwide, TAP is a large European airline. TAP currently serves a

fleet of 55 Airbus aircraft, plus 16 that are operated by the regional subsidiary carrier PGA [2].

1.1 Economic Scenario

Just recently, in 2010, TAP has achieved a profit of roughly 62.3 million euros, an increase of

8.7% against the previous year, and this way a positive balance which had not happen since

2008 – one of the worst years for the commercial aviation in history [3]. TAP is clearly a winner

in the vast sea of airlines that nowadays struggle to remain afloat with only marginal profits.

The global aviation industry has been living in a precarious balance between revenue and costs

since the beginning of 2000, marked by the global economic slowdown and the terrorist attacks

of 11 September 2001 [4]. At this time, global economy is in recession as a consequence of the

increasing demand of resources by the emerging countries which unbalance the global markets.

To make matters worse, crude prices have been rising and in the past few years have been

higher than ever (Figure 1– (a)).

Figure 1 - (a) - Jet Fuel costs in the US [5]; (b) – Overall Airline Costs Mirroring Fuel Price Changes (1971

as Base Year1) [6].

According to ATA (Air Transport Association of America), crude price is now the largest cost in

airlines’ operation besides, as fuel prices increase flights become less profitable (Figure 1– (b)).

Crude price has an inherent growing tendency, which associated with its high economic and

political unpredictability makes business planning very difficult. When fuel prices rise rapidly,

airlines have limited options to mitigate these costs: they either generate more revenue or

decrease nonfuel expenses [7].

Consequently, optimization is the key to success in this new era, and optimization is exactly

what the present work is about.

1 Overall Airline Cost Index not to be confused with Cost Index (CI) usually expressed in kg/min.

2

1.2 Relevance

In commercial aviation, profit demands cargo and passengers, which in an engineer’s point of

view translates as weight. To maximize aircraft’s weight at takeoff, aircraft performance

optimizations must take place.

Although takeoff and landing represent only a small portion of the total operation of an aircraft,

performance of these two phases is considered very important due to entirely different reasons

[8]. First, a great majority of accidents (mostly attributed to pilot error) occur during landing or

take-off. Second, it is the take-off portion that establishes the engine sizing (in conjunction with

air worthiness requirements) for design of civil aircraft. More importantly, civil airlines more than

ever, need to optimize the weight of their aircraft to become more competitive.

This way, it is not a surprise that “takeoff and landing are the most strictly regulated segments of

a flight” [9, pp. 16-2]. For safety reasons, authorities such as the JAA (Joint Aviation Authority)

and the FAA (Federal Aviation Administration) have laid down operational procedures to ensure

a safe practice during the takeoff and landing stages.

Performance data calculation and optimization reflect through the whole airline operation.

Besides having flight safety as its ultimate concern, data availability and easy recalculation

makes airline’s operation more safeguarded to operation disruptions due to external agents.

Also, the quality of this data reflects in the airline’s balance sheets at the end of the year as the

result of possible savings in different areas of operation [1].

1.3 Airlines’ Operational Context

Nowadays, airlines either subcontract or calculate takeoff performance by themselves. This

data is presented in the form of tables such as the Regulatory TakeOff Weight (RTOW) and

Regulatory Landing Weight (RLW) charts. Generally speaking, they consist in a list of weights

(RTOW) and operational speeds as a function of specific parameters (such as aircraft model,

runway characteristics and weather conditions). Besides providing utmost important data to

airliner pilots, RTOW charts also provide important information for several ground operations,

especially for the flight dispatcher who uses these documents during the planning and

monitoring processes of aircraft’s activities. In a similar way, to dispatch an aircraft, an operator

has to verify landing requirements based on aircraft certification and on operational constraints

defined in regulation, which is usually achieved by interpretation of RLW charts.

1.4 Objectives

The present work focuses in the development of a new performance optimization application –

Takeoff and Landing Performance Program (TLP) – intended for on ground use. It is intended to

run under windows environment and was projected to be as user-friendly as possible. The

resulting optimization output is presented in the form of runway takeoff weight and landing

charts, which can be either printed or exported as PDF and Excel files, making TLP a dynamic

and valuable tool for TAP’s engineers.

This project is borne alongside TAP’s in-house project for an Electronic Flight Bag (EFB) – an

electronic system that displays a variety of aircraft data and executes performance calculations

[10].

3

1.5 Dissertation Structure

The present work is split in 8 distinct chapters. The current chapter provides the conceptual

goals and context for the developed work. TAP’s Case Study can be understood as an

extension of the present introduction; it intends to translate the actual state of RTOW chart

creation, maintenance and usage at TAP Portugal and foresee how the present work will

improve these processes. Chapters 3 and 0 provide the conceptual basis for chapter 5 - Takeoff

Optimization. Landing Performance is addressed on chapter 6. Chapter 7 - Takeoff and Landing

Performance Application (TLP) - describes the computational application that results from the

present work. Finally, a conclusion is presented on chapter 8, together with final thoughts on the

present topic.

4

2. TAP’s Case Study

In this section the author intends to understand the actual state of RTOW charts creation,

maintenance and usage at TAP Portugal, identifying the operational needs and new ways to

improve the current processes. Notice that the information in the following lines was retrieved

directly from TAP’s personnel.

There are two main target groups at TAP Portugal that currently handle RTOW charts in their

daily activities and that will benefit directly from the present work: the flight dispatchers and the

flight operations engineering department. Pilots will also benefit from this software since they

will be allowed to perform calculations for training purposes, outside their schedule flights.

2.1 Flight Dispatch

The flight dispatcher is responsible for planning and monitoring the aircraft’s activities. They

receive the expected payload for each flight from Load Control and use TAP’s flight plan

calculation program to calculate the ICAO2 flight plan which they must submit to

EUROCONTROL. Also, the required fuel is also computed and an automated message is sent

to the fuel suppliers.

Simply put, he must check the weather conditions by consulting the newest Aviation Routine

Weather Report (METAR) or Terminal Aerodrome Forecast (TAF), which he can retrieve

through TAP’s intranet system. Depending on the weather conditions he will know (or at least

predict) which runway will be in operation at takeoff (headwind improves aircraft performance).

Then, he must access TAP’s RTOW chart repository and find the chart that matches the aircraft

(for which he is planning the flight) and runway (that he identified by reading the weather

conditions).

However, it is a common practice to have several charts for the same aircraft and runway, each

one corresponding to different conditions (such as different aircraft configurations, or different

runway conditions or intersections). Many times this process requires the flight dispatcher to

interpolate between different lines of the same chart (e.g. temperature value between two lines),

or to perform additional performance calculations to contemplate conditions that are not present

in any chart in the repository (e.g., slush on the runway).

2.2 Flight Operations Engineering Department

The Flight Operations Engineering Department is without a doubt in need of a new and more

dynamic aircraft performance calculation tool.

One example of a task performed by TAP’s engineers is the calculation of aircraft maximum

payloads; currently, to accomplish this task the engineer needs to gather several data that is

spread across the innumerous RTOW charts. First, he must identify which aircraft configuration

results in a higher Maximum TakeOff Weight (MTOW) for the airport’s reference temperature.

Since each chart only displays information related to two of the possible configurations, he must

handle different charts at the same time. Additionally, it may be necessary to perform

interpolations since the airport reference temperature might not be strictly specified in those

tables. The whole process can be extremely time-consuming and give way to possible

2 ICAO - International Civil Aviation Organization.

5

mistakes. Besides, since the current tables are stored as PDF files, the engineer may find

himself copy-pasting the values from the charts to another work tool such as Microsoft Excel or

Matlab.

2.3 Remarks

Summing up, it would appear that in both cases the performance considerations can be very

time-consuming. Also, when they demand delicate performance calculations, they leave room

for human error. Furthermore, most times, hand-made performance optimizations tend to use

more conservative approaches than the computational methods and consequently it is evident

that there is room for optimization. Also, it seems that the engineers are lacking of a more

dynamic tool, one that could, for instance, export optimization results as an Excel file so that the

data could be handled without requiring to be manually processed.

6

3. Aircraft Performance

The aim of this section is to provide the necessary background on aircraft performance for the

following chapters of the current work. Aircraft operational limitations and configurable settings

will be object of full attention.

3.1. Aircraft Settings

3.1.1. Aircraft Configuration

Modern aircraft take advantage of high-lift devices like slats and flaps (Figure 2) to change their

wing shape and respective aerodynamic performance.

Figure 2 - High-lift devices on an Airbus A340 (adapted from [11]).

The main function of trailing edge flaps is to increase the camber (curvature) and the surface of

the wing enabling it to produce more lift, at the expense of increased drag [9]. There are many

different flap designs. The following picture represents a simple flap (a) and a fowler flap (b).

The last one can be seen in the Airbus A340 for example [12].

Figure 3 – Simple (a) and fowler (b) trailing edge flaps [9].

In opposition, the purpose of leading edge high-lift devices like slats (Figure 4) is not to increase

the lift coefficient for a given angle of attack. Their aim is to delay airflow separation until a

higher angle of attack is reached and this way helping the wing to achieve a higher maximum lift

coefficient than would be otherwise possible [9].

7

Figure 4- Slat [9].

Figure 5 - Flaps lever [13].

The pilot uses the flaps lever (Figure 5) to select simultaneously the slat and flap setting.

Consequently, it is a common practice to refer to the “flap setting” and the “aircraft

configuration” interchangeably. For that reason the author will make no distinction between

these two terms.

For example, considering an Airbus A320, the five positions of the flaps’ lever correspond to the

following surfaces positions:

Lever Position Slats Flaps Flight Phases

0 0° 0° Cruise / Hold

1 18° 0° Hold / Approach

10°

Takeoff

2 22° 15° (14°) Approach

3 22° 20° (21°) Approach / Landing

Full 27° 35°(*) (25°) Landing (*) : 40° for A320 with IAE

3 engine or A319

( ) : setting for A321

Table 1 - A320 family Flap and Slat configurations [14].

Additionally, some aircraft configurations also activate the speedbrakes (e.g. configuration FULL

or configuration 3 for A321 [14]).

3.1.2. Engine Bleeds

Aircraft engine bleeds are required by the Anti-Icing and the Air Conditioning systems. The following figure represents the Environmental Control System (ECS) schematic; its purpose is to highlight the connections between the engines, the Anti-Icing and the Air Conditioning systems (see ATA 21 refers

to Air Conditioning ATA 26 refers to Pneumatic Systems

Figure 6).

From an aircraft performance engineer’s perspective, operation of any of these systems

degrades the performance of the aircraft since the “engine air bleed for de-icing or air

conditioning, implies a decrease in engine thrust” [15, p. 124]. This reflects negatively on the

climb gradients and consequently on the takeoff and landing performance.

Although the air conditioning can be switched on or off (depending on the company policy), the

anti-icing system must be switched on if the environmental conditions demand it (according to

regulation).

3 International Aero Engines (engine manufacturer)

8

ATA

4 21 refers to Air Conditioning

ATA 26 refers to Pneumatic Systems

Figure 6 - Environmental Control Systems for the A320 family [14].

3.1.3. Aircraft Status (MEL/CDL)

Aircraft status is dealt with by the Minimum Equipment List (MEL) and the Configuration

Deviation List (CDL).

“MEL procedures were developed to allow the continued operation of an aircraft with specific

items of equipment inoperative under certain circumstances. The (…) [FAA and the JAA have]

found that for particular situations, an acceptable level of safety can be maintained with specific

items of equipment inoperative for a limited period of time, until repairs can be made. The MEL

document describes the limitations that apply when an operator wishes to conduct operations

when certain items of equipment are inoperative” [16].

Under certain conditions, aircraft may be approved for operations even with missing secondary

airframe and engine parts [16]. The aircraft source document for such operations is the CDL.

Since under these circumstances aircraft performance may be affected, considerations must be

made for the takeoff and landing optimization processes. For this purpose, the developed

computational method takes advantage of a CDL database (provided by the manufacturer) as

will be explained in the 8th chapter of the current work.

In the aircraft’s MEL/CDL manual items are addressed by their ATA code. Table 2 is an

example of the CDL items referenced in the MEL/CDL manual, in this particular case, for an

Airbus A319-111.

4 Air Transport Association of America Spec 100 – A broadly used specification that provides

common reference for all commercial aircraft documentation. It defines a widely-used outline for aircraft parts and systems, according to their characteristics and functions which are referred as ATA Chapters [34].

9

ATA Chapter Items

ATA21 AIR CONDITIONING ATA21-01 Ram air inlet flap ATA21-01 Ram air inlet flap (MOD 26363) ATA21-02 Ram air outlet flap

ATA27 FLIGHT CONTROLS ATA27-01 Flaps track fairing

ATA27-08 Seal between Inboard and Outlet flap

ATA33 LIGHTS ATA33-04 Upper 7LV and lower 6LV anti-collision (beacon) light cover

ATA52 DOORS

ATA52-01 Toilet servicing door and drainage 172AR ATA52-02 Access door to hydraulic ground connectors. 197CB - 197EB - 198CB ATA52-04 Access door to opening control of landing gear doors on ground 195BB ATA52-08 Cargo door opening system - Access door of cargo opening system 134AR ATA52-09 Nose landing gear main doors (713, 714) ATA52-10 Nose landing gear aft doors (715, 716) ATA52-12 Main landing gear door (732, 742) (flight with gear up) ATA52-13 Main landing gear door (733, 743) (flight with gear up) ATA52-14 Main landing gear door (732, 742) (flight with gear down) ATA52-15 Main landing gear door (733, 743) (flight with gear down) ATA52-16 Main landing gear door (734, 744) (flight with gear down) ATA52-18 Main landing gear door: Seal on secondary hinged fairing ATA52-19 Pax door upper cover plate ATA52-22 Forward cargo door access cover panel 825AR ATA52-23 Aft cargo door access cover panel 826AR

ATA54 NACELLES/PYLONS ATA54-01 Nacelle Strake

ATA54-03 Pylon pressure relief door 413 (423)BL - 414 (424)BR

ATA57 WINGS ATA57-01 Wing tip fence - Complete wing tip fence ATA57-01 Wing tip fence - Lower part of wing tip fence

Table 2 - A319-111 CDL (data from LPCAirport database).

3.2. Aircraft Limitations

3.2.1. Limiting Speeds

This subchapter is not an enumeration of all the limiting speeds. Since its aim is to provide the

reader with a background for the subsequent chapters, the author will focus on the most

relevant definitions and the ones that have a direct impact on the takeoff and landing

optimizations.

a) Stall Speed

Stall is a loss of lift caused by either the breakdown of airflow over the wing when the angle of

attack passes a critical point, or at a fixed angle of attack, when the speed goes bellow a critical

value.

Air velocity increases over the wing with the angle of attack5, it follows that air pressure

decreases and consequently the lift coefficient increases. This can be seen across the blue

section of the figure below:

5 The angle formed between the relative airflow and the chord line of the airfoil [30].

10

Figure 7- CL versus angle of attack (adapted from [15]).

The lift coefficient increases until it reaches the maximum lift point (CLMAX). From this point on

the lift coefficient suffers a sudden decrease.

This occurrence is called a stall and two speeds can be identified [15]:

VS1g, which corresponds to the maximum lift coefficient, when the load factor is equal to

one.

VS, which corresponds to the conventional stall, when the load factor is already less

than one.

VS1g is the reference stall speed for the airbus fly-by-wire aircraft and consequently for all the

TAP’s aircraft. Consequently, as in Airbus official documentation, in this work VS is referred to

as VS1g.

b) Minimum Control Speed on the Ground (VMCG)

The Minimum Control Speed on the Ground (VMCG) defines the minimum speed that ensures

that the aircraft will remain controllable during the takeoff roll, in the event of an engine failure

on the ground [17].

According to regulations, the lateral excursion must be less than 30 feet after an engine failure

on the ground (see Figure 8) (JAR 25.149 (e)).

Figure 8 - VMCG (adapted from [18]).

11

The following conditions are assumed for VMCG determination [18]:

• Most critical takeoff configuration

• Most unfavorable center of gravity

• Most unfavorable takeoff weight

• Aircraft trimmed for takeoff6

• Operating engines on takeoff power

VMCG mainly depends on [15]:

Engine(s) thrust and position

Pressure altitude

For further information on VMCG see Appendix A - JAR 25.149 (e).

c) Minimum Control Speed in the Air (VMCA)

Minimum Control Speed in the Air (VMCA) is the speed at which in case of an engine failure the

aircraft can be controlled either with a 5 degree maximum bank angle (Figure 9 – a), or with

zero yaw (Figure 9 – b) (JAR 25.149 (b) and (c)).

Figure 9 - Sideslip angle (a) and bank angle (b) in a one-engine-inoperative condition (adapted from [17]).

All the conditions for the determination of VMCG are assumed plus [18]:

• The aircraft is airborne and out of ground effect

• Landing gear is retracted

• Inoperative engine windmilling7

Further information on VMCA is presented in Appendix A - JAR 25.149, paragraphs (b) and (c).

6 Trimmers adjusted in order to get the required hands-off pitch attitude prior to the takeoff [30].

7 Turning around by wind force only, without engine power [30].

12

d) Minimum Unstick Speed (VMU)

According to regulation, “VMU is the calibrated airspeed at and above which the airplane can

safely lift off the ground, and continue the takeoff” (JAR 25.107 (d)).

VMU is determined during low speed flight test demonstration (Figure 10). The control stick is

pulled to the limit of the aerodynamic efficiency of the control surfaces, taking the aircraft on a

slow rotation to an angle of attack at which either the maximum lift coefficient is achieved, or the

tail strikes the runway (for geometrically limited aircraft) [15] (Figure 10).

Figure 10 - VMU determination (adapted from [17] and [18]).

Two minimum unstick speeds must be determined and validated during flight tests:

• all engines operatives (AEO) : VMU(AEO)

• with one engine inoperative (OEI) : VMU(OEI)

In the one-engine inoperative case, VMU(OEI), sufficient lateral control must be ensured in order to

prevent that an engine or a wing hits the ground [18].

It appears that [18]:

(1)

See Appendix A - JAR 25.107, paragraph (d) for additional details on VMU.

e) Minimum Speed During Approach and Landing (VMCL)

VMCL “is the calibrated airspeed at which, when the critical engine is suddenly made inoperative,

it is possible to maintain control of the aircraft with that engine still inoperative, and maintain

straight flight with an angle of bank of not more than 5°” (JAR 25.149 (f)). The establishment

condition for the VMCL may be consulted in the Appendix 1 - JAR 25.149, paragraph (f) and (h).

For aircraft with three or more engines a minimum speed during approach and landing with a

critical engine inoperative - VMCL(OEI) - is also determined. VMCL(OEI) establishment conditions are

provided in Appendix A - JAR 25.149, paragraphs (g) and (h).

f) Maximum Brake Energy Speed (VMBE)

Assuming that aircraft brakes absorb the whole kinetic energy in the form of heat, during

braking, at higher speeds than VMBE the brakes become irreversibly damaged [15] [18].

13

VMBE depends on [18]:

• Aircraft weight

• Meteorological conditions

• Runway slope

g) Maximum Tire Speed (VTIRE)

VTIRE is the maximum ground speed specified in order to limit the centrifugal forces and heat

that may damage the tire structure. This speed is specified by the tire manufacturer [18].

For most Airbus aircraft models, VTIRE = 195 knots [15].

3.2.2. Structural Weights

The total weight of an aircraft is usually split as illustrated in the following figure:

Figure 11 - Aircraft Weights [15].

MEW, or Manufacturer’s Empty Weight, is “the weight of the structure, power plant, furnishings,

systems and other items of equipment that are considered an integral part of the aircraft. It is

essentially a dry weight, including only those fluids contained in closed systems“, [15, p. 42].

OEW stands for Operational Empty Weight, which is the Manufacturer’s Empty Weight plus the

operators items such as the flight and cabin crew and their luggage, documents, seats and

fluids (e.g. unusable fuel, engine oil, toilet) [19].

DOW or Dry Operating Weight is the total weight of the aircraft when it is ready for a specific

type of operation, excluding all usable fuel and traffic load (JAR-OPS 1.607 (a)).

14

ZFW, or Zero Fuel Weight, is the Dry Operating Weight plus the traffic load (passengers,

passenger’s bags and cargo) [19].

ZFW = DOW + traffic load

TOW or Takeoff Weight is the aircraft weight at the start of the takeoff run. It equals the Zero

Fuel Weight plus the fuel at brake release point or the Landing Weight plus the trip fuel (“the

weight of the fuel required to cover the normal leg without reserves”, [15] [19]:

TOW = DOW + traffic load + fuel reserve + trip fuel

LW stands for Landing Weight, which is the weight of the aircraft at the moment of landing at

the destination airport. It is equal to Zero Fuel Weight plus the fuel reserve [15]:

LW = DOW + traffic load + fuel reserve

3.2.3. Maximum Structural Weights

As stated in JAR 25.25, aircraft maximum weights must never “exceed the highest weight

selected by the applicant for the particular conditions”, neither “the highest weight at which

compliance with each applicable structural loading and flight requirement is shown” (see

Appendix A - JAR 25.25 for more detailed information).

Taking this into account, the Maximum Structural is the maximum permissible total aircraft

weight at the start of the take-off run (JAR-OPS 1.607 (d)) and consequently TOW must never

exceed this value. In the other hand, the Maximum Structural Landing Weight represents the

maximum permissible total aircraft weight at the moment of landing (JAR-OPS 1.607 (c)).

3.2.4. Environmental Envelope

The environmental envelope (see Figure 12) consists in the operational limits for the ambient air

temperature and operating altitude (pressure altitude). Inside this envelope, aircraft

performance has been fully defined and its respective systems have met certification

requirements [15].

The green area in Figure 12 denotes the takeoff and landing operational limits.

Figure 12 - A319-111 Environmental Envelope (adapted from [20]).

15

3.2.5. Engine Limitations

“The main cause of engine limitations is due to the Exhaust Gas Temperature (EGT) limit”, [15,

p. 44]. The following table illustrates a typical example of EGT limits, in this case for an A340-

312 aircraft:

Operating Condition Time Limit EGT Limit Note

TOGA 5 min

950 °C

10 min Only in case of engine failure

MCT Unlimited 915 °C

CL Unlimited 915 °C

Starting 725 °C

Table 3 - Thrust Setting and EGT Limit for an A340-312 (CFM56-5C3 engine) [21].

TOGA stands for Takeoff-Go-Around [22]. The Takeoff and Go-Around thrust represents the

maximum thrust available for takeoff and go-around sequences; it is certified for a maximum of

5 minutes (or 10 minutes if an engine failure occurs). MCT, or Maximum Continuous Thrust [22],

is the maximum thrust that can be applied unlimitedly during a flight. “It must be selected in

case of engine failure, when TOGA thrust is no longer allowed due to time limitation”, [15, p.

42]. CL stands for Climb [22] and represents the maximum thrust available during the climb

phase.

Notwithstanding its relevance, EGT is not the only limitations to take into account during aircraft

operation. Aircraft’s engines perform differently according to the current Outside Air

Temperature (OAT) and pressure altitude. These performance variations must be taken into

account.

As a general rule, at a given pressure altitude, the available thrust decreases with temperature

past a certain value of temperature - the reference temperature (TREF). On the other hand, at a

given temperature, any increase in the pressure altitude leads to decreasing the available

takeoff thrust. The following figure illustrates the engine thrust variation according to both these

factors:

Figure 13 - TOGA thrust versus OAT and PA for a given engine type [15].

16

4. Takeoff Performance

In the present chapter the author introduces the agents that condition the takeoff performance,

and that will in some way limit it. First, the runway distances and specifications are presented,

followed by the surrounding obstacles and resulting flight path limitations. Then the outside

elements and their influence will be described, such as the weather and the runway conditions.

Finally all the resulting limitations will be summarized in a diagram to provide a better overall

comprehension.

The takeoff sequence can be split in three major phases as illustrated in the following figure:

Figure 14 - Takeoff Profile [15].

During the takeoff phase, the aircraft must achieve sufficient speed and angle of attack in order

to develop sufficient lift (L) to overcome its weight (mg):

⁄ (2)

In which:

– Air density (fixed) S – Aerodynamic reference wing area (fixed) V – Airspeed – Lift coefficient (increases with angle of attack)

4.1. Operational Speeds

a) Engine Failure Speed (VEF)

Due to regulations, the most critical engine8 failure must always be taken into account to ensure

a safe takeoff. VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF

may not be less than VMCG (JAR 25.107 (a)).

b) Decision Speed (V1)

“For every single takeoff, there are three critically important speeds that the pilot must observe

carefully”, V1, VR and V2 [9]. According to regulation, V1, “in terms of calibrated airspeed, is the

take-off decision speed” (see Appendix A – JAR 25.107, paragraph (a) for further regulatory

description). In JAR Part 1, V1 is defined as “the maximum speed in the takeoff at which the pilot

must take the first action” (e.g. apply brakes, reduce thrust, deploy speed brakes) in order to

stop the airplane within the limits of the runway.

8 Critical Engine “means the engine whose failure would most adversely affect the performance

or handling qualities of an aircraft, i.e. an outer engine on a four engine aircraft” (JAR 1.1).

17

V1 can be selected by the applicant, assuming that an engine failure has occurred at VEF (JAR

25.107 (a)). Since even the best pilots have some time delay between making a decision to

reject the takeoff and actually initiate the rejected takeoff (RTO) procedure (by first applying the

wheel brake) [9], the resulting reaction time ( ) must be taken into account:

Figure 15 - Decision Speed [15].

Consequently, V1 corresponds to the VEF speed plus one second of acceleration with one

engine inoperative [9] [15]:

(3)

Additionally, V1 must be less than or equal to VMBE or VR, whichever is less [9]:

{

(4)

It follows that sometimes V1 does not have a unique solution, corresponding instead to a range

of valid values. In a similar way to other airlines, TAP defines V1 as the lower bound of that

possible range which is the most conservative value: a lower V1 grants the pilot with more time

to execute the RTO procedure.

c) Rotation Speed (VR)

VR is the calibrated airspeed at which the pilot initiates the rotation sequence by, pulling back on

the control column, raising the nose of the aircraft to its takeoff attitude [9]. According to

regulation, VR must be less than V1 and 105% of VMCA (JAR 25.107 (e)):

(5)

This speed has critical implications for takeoff safety, because it directly affects the liftoff speed,

VLOF and the initial takeoff climb speed V2 as well as the takeoff distance [9]. For further

regulatory information on VR see Appendix A – JAR 25.107 (e).

d) Lift-off Speed (VLOF)

VLOF is the calibrated airspeed at which the aircraft lifts off the ground [18]. In order to ensure

good flight handling qualities at lift off, the authorities placed two constraints on VLOF:

18

(6.1)

(6.2)

These conditions are for geometrically limited aircraft such as the A319, A320, A321, A330 and

A340 (all of TAP’s fleet), for more detailed regulatory information see Appendix 1 – JAR 25.107

(e).

Additionally, the lift off speed, in terms of grounds speed, must not exceed the maximum tire

speed [18].

e) Takeoff Climb Speed (V2)

V2 is the minimum calibrated airspeed that must be reached at a height of 35 feet above the

runway surface, assuming the event of an engine failure [15]. 35 feet is the value used for the

usual dry runway situation; for non-dry runway conditions, and for the engine-inoperative takeoff

case only, this height is reduced to 15 feet [9].

The regulations place the following requirements on V2 (JAR 25.107 (b) and (c)):

(7.1)

(Fly-By-Wire aircraft) (7.2)

(other aircraft) (7.3)

As the whole TAP fleet is composed by Fly-By-Wire

9 (FBW) aircraft, the author will consider

from this point on that V2 must be at least 1.13 times the VS1g.

For further reading on this topic, see Appendix A – JAR 25.107, paragraphs (b) and (c).

f) Speed Summary

The following figure illustrates the relationships and the regulatory margins between the certified

speeds seen in chapter 5 (VS1g, VMCG, VMCA, VMU, VMBE, VTIRE) and the takeoff operating speeds

(V1, VR, VLOF, V2).

Figure 16 - Takeoff Speed Summary and Limitations related to V1, VR, VLOF and V2 [15].

9 Fly-By-Wire is a kind of “technology which interprets movements of the pilot’s controls and,

with the aid of computerized electronics, moves the control surfaces accordingly” [30].

19

4.2. Runway

“The runway is a rigid or flexible rectangular area, on concrete or asphalt, used for takeoff and

landing”. In addition to the runway (RWY), there are two regions that must be considered when

accounting for the available takeoff lengths: the stopway (SWY) and the clearway (CWY).

Notice that although these areas contribute to a better aircraft performance, they are not

mandatory, so they may not be present in every runway.

The Stopway is a rectangular area beyond the takeoff runway designated by the airport

authorities for use in decelerating the aircraft in case of a RTO [18].

Figure 17 - Stopway (adapted from [15]).

In a similar way, the clearway (CWY – see Figure 18) is also a rectangular area beyond the

runway, located on the same centerline and under control of the airport authorities [18]. Its main

purpose is to provide a clear takeoff path (without obstacles).

Figure 18 - Clearway (adapted from [15]).

4.2.1. Available Takeoff Lengths (TORA, ASDA and TODA)

There are three major takeoff lengths that must be well known prior to any takeoff performance

evaluation on any runway: the Takeoff Run Available (TORA), the Accelerate Stop Distance

Available (ASDA) and the Takeoff Distance Available (TODA).

TORA is either equal to the runway length, or to the distance from the runway entry point

(intersecting taxiway) to the end of the runway (JAR-OPS 1.480).

ASDA is the runway length available for acceleration and subsequent deceleration, including

the stopway, if any [18]. In other words, it is the TORA plus the stopway.

As for TODA, it is “the length of the take-off run available plus the length of the clearway

available” (JAR-OPS 1.480).

20

Figure 19 summarizes these three definitions.

Figure 19 - Available Takeoff Lengths (adapted from [15]).

4.2.2. Lineup Adjustments

Airplanes typically enter the takeoff runway from an intersecting taxiway. When this intersection

has a high degree angle (e.g. 90°, 180°) the previous distances (ASDA and TODA) must be

corrected. In other words, a lineup adjustment must be considered (see Figure 20 and Figure

21).

Figure 20 - Lineup Adjustment, Top (adapted from [15]).

Figure 21 - Lineup Adjustment, Side10

(adapted from [15]).

10

Notice that in this particular situation the runway does not have a clearway. Consequently, if there were no lineup adjustments: ASDA = TODA.

21

In this particular case, for a 90° entry type, the following values apply:

Aircraft Model ASDA Correction TODA Correction

A320 83 ft 42 ft

A330-3XX 158 ft 74 ft

A340-3XX 169 ft 85 ft

Table 4 - Lineup Adjustments for 90° Runway Entry [18].

4.2.3. Takeoff Lengths

a) Takeoff Distance (TOD)

According to regulation (see Appendix A, JAR 25.113 for a more complete description),

assuming a set of operational conditions (outside air temperature, pressure, weight, etc.), the

takeoff distance on a dry runway is given by [15]:

{ } (8.1)

In a similar way, on a wet runway the takeoff distance is given by [15]:

{ } (8.2)

Naturally, the takeoff distance must be less than the available takeoff distance:

(9)

b) Takeoff Run (TOR)

Like in the TOD determination, on a dry runway the takeoff run is given by [15] (see Appendix A

– JAR 25.113 for further regulatory information):

{ } (10.1)

On a wet runway, however, it is a slightly different [15]:

{ } (10.2)

It follows:

(11)

c) Accelerate-Stop Distance (ASD)

The accelerate-stop distance on a dry runway is the greater of the following values [15] (see

Appendix A – JAR 25.113 for supplementary information):

{ } (12.1)

As for the wet runway situation, it is the greatest of the following three values [15]:

{ } (12.2)

Naturally:

(13)

22

4.2.4. Runway Slope

“Airbus aircraft are all basically certified for takeoff on runways whose slopes are between -2%

and +2%” [15, p. 77]. A positive slope increases the takeoff distances and reduces the

accelerate-stop distances, a negative slope results in the opposite:

Figure 22 - Runway slope effect on takeoff performance [15].

4.3. Obstacles and Takeoff Trajectory

In order to account for the surrounding obstacles and climb gradients restrictions, the takeoff

trajectory must be subject of analysis.

4.3.1. Takeoff Flight Path

As seen before, the aircraft is accelerated on the ground to VEF, at which point the critical

engine is considered inoperative, remaining this way for the rest of the takeoff. Also, V2 speed

must be reached before the aircraft reaches 35 ft above the ground. This is the transition point

to the first segment of the takeoff flight path which will last “to a point at which the aircraft is at a

height of 1500 ft above the takeoff surface, or at which the transition from the takeoff to the en-

route configuration is completed and the final takeoff speed is reached” (JAR 25.111).

It is standard industry practice to split the takeoff flight path into four segments. These are

distinctly separated pieces of the profile, each characterized by a different configuration or

thrust settings [9].

Figure 23 and Table 5 provide a good description of the takeoff flight path and its respective

segments. Notice that according to TAP’s policy the minimum level-off height (gross height at

the third segment) must me at least 1500 ft (instead of 400ft). Also, the minimum height of the

transition point from the final segment to climb is 3500 ft (instead of 1500 ft). These are, of

course, more conservative definitions.

23

Figure 23 - Takeoff Path and Definition of Various Segments [15].

First

Segment Second

Segment Third

Segment Final Segment

Minimum Climb Gradient (OEI)

Twin 0.0% 2.4% - 1.2%

Quad 0.5% 3.0% - 1.7%

Start When VLOF reached Gear

retracted

Acceleration height is reached

En route configuration

achieved

Slats/Flaps Configuration

Takeoff Takeoff Slats/Flaps retraction

Clean

Engine Rating TOGA/FLEX11

TOGA/FLEX TOGA/FLEX MCT

Speed Reference VLOF V2 Acceleration from V2 to

Green Dot12

Green Dot

Landing Gear Retraction Retracted Retracted Retracted

Ground Effect Without Without Without Without

Table 5 - Takeoff Segments Characteristics (adapted from [15]).

11

Flexible takeoff is explained in chapter 5.4 12

Green Dot speed is the optimum climb gradient speed, one engine out (APT INT A320-214)

24

4.3.2. Obstacle Clearance

Most of the time, runways have surrounding obstacles that must be taken into account prior to

takeoff, to determine that the aircraft is able to clear them with a certain safety margin. This

leads to the definition of gross and net flight paths.

Also, “Some airports are located in an environment of penalizing obstacles, which may

necessitate turning to follow a specific departure procedure” [15, p. 65]. Turning departures are

subject to specific conditions.

a) Gross and Net Flight Paths

The gross flight path is “the takeoff flight path actually flown by the aircraft” (JAR 25.115 (a)),

while the net flight path is the “gross takeoff flight path minus a mandatory reduction” (JAR

25.115 (b)). This mandatory reduction, based on a climb gradient reduction, must grant a safety

margin of 35 ft between the aircraft and every obstacle in its flight path (see Figure 24). Two

engine aircraft have a gradient penalty of 0.8%, while four engine aircraft have their “takeoff

path reduced at each point by a gradient equal to” 1.0% (JAR 25.115 (b)).

Figure 24 - Gross and net takeoff paths [15].

b) Takeoff Turn Procedure

According to regulation, no track changes are allowed before the aircraft achieves a height

equal to one half its wingspan (Table 6) and before reaching at least 50 ft above the end of

TORA.

Aircraft Type Wingspan Minimum height to start a track change

A319/A320/A321 34.10 m (111 ft 10 in) 56 ft A330-200/300 60.30 m (197 ft 10 in) 99 ft A340-200/300 60.30 m (197 ft 10 in) 99 ft

Table 6 - Minimum height to start a track change according to wingspan [18].

25

Also, no bank angle should exceed 15° under a 400 ft height. Above 400 ft, bank angles must

be under 25°. If at any time the banking angle gets over 15°, then the whole net flight path must

clear all obstacles by at least 50 ft (JAR-OPS 1.495 (c)).

Greater banking angles, other than the ones specified, may be applied but are subject to

specific approval by the Authority (JAR-OPS 1.495 (c)).

4.3.3. Departure Sector

The departure sector delimits “an area surrounding the takeoff flight path, within which all

obstacles must be cleared, assuming they are all projected on the intended track” [15, p. 71].

The following figures represent departure sectors with and without heading changes over 15°.

Figure 25 - Departure Sector for track changes under 15° [15].

Figure 26 - Departure Sector for track changes over 15° [15].

“E” stands for the width of the departure sector, which must be equal to 90 m plus 0.125 x D or

60 m plus 0.125 x D, for aircraft with a wingspan of less than 60m. “D is the horizontal distance

the aircraft has traveled from the end of the take-off distance available or the end of the take-off

distance if a turn is scheduled before the end of the take-off” (JAR-OPS 1.495 (a)).

26

The following table represents the semi-width (1/2E0) at the start of the departure sector for

TAP’s aircraft:

Aircraft Type Wingspan 1/2E0

A319/A320/A321 34.10 m (111 ft 10 in) 56 ft A330-200/300 60.30 m (197 ft 10 in) 99 ft A340-200/300 60.30 m (197 ft 10 in) 99 ft

Table 7 - Semi-width ( E0) at the Start of the Departure Sector [18].

In the situation where there are no heading changes over 15°, the maximum width of the

departure sector is 300 m if the pilot is able to maintain the required navigational accuracy and

600 m otherwise (JAR-OPS 1.495 (d)). When the aircraft performs track changes above 15°

these values increase to 600 and 900 m, respectively (JAR-OPS 1.495 (e)).

4.4. Outside Elements

Considerations must be made to account for the external conditions of the day which can vary

considerably on a daily basis.

4.4.1. Wind

For performance purposes, only the wind component that is parallel to the runway (headwind –

HW) is considered (Figure 27). The crosswind component can be safely overlooked in the

takeoff optimization because it has a negligible effect on the aircraft acceleration [9].

Figure 27 - Headwind determination.

The headwind component has a positive effect on takeoff performance by shortening the takeoff

distances (the ground speed is reduced - see Figure 28). In the presence of tailwind the

opposite occurs, the takeoff performance degrades and the resulting takeoff distances increase.

27

Figure 28 - Headwind effect on ground speed [15].

According to regulation, takeoff performance calculations must only consider 50% of the actual

headwind component, or 150% of the actual tailwind component (JAR-OPS 1.490 (c)).

Notice that usually the takeoff software applications perform the 50% 150% corrections

internally, so the wind input is simply the headwind or the tailwind, respectively. This is, of

course, the case with TLP as well.

4.4.2. Pressure Altitude

As was seen before, in chapter 3, engine performance degrades with pressure altitude: engine

thrust decreases so the takeoff distances increase and the climb gradients decreases.

Additionally, when the pressure altitude increases, the corresponding static pressure (PS) and

air density decreases (eq. 14 – adapted from [23]) [15]. Consequently the pressure altitude also

has a direct impact on aerodynamics (eq. 15).

(14)

(15)

To compensate for a decrease in the air density, the true airspeed (TAS) of the aircraft must be

increased and therefore the takeoff distance is also increased [15].

Summing up:

Figure 29 - Pressure altitude effect on takeoff performance [15].

4.4.3. Outside Air Temperature

When the outside air temperature (OAT) increases the air density ( ) decreases (see eq. 14).

Consequently the takeoff performance degrades in a similar way as with the pressure altitude:

TAS must increase, therefore the takeoff distances increase as well (see Figure 29).

28

4.4.4. Runway Condition

The runway condition is utmost important when accounting for the takeoff (and landing)

performance. The runway is, after all, the surface between the aircraft and the ground.

Therefore its state, or condition, defines the interaction between the two and, consequently, can

take major impact in the aircraft acceleration or stopping capabilities, when compared to a dry

runway.

Since this is a topic of great complexity, this subsection can be seen as only a summary of the

major considerations to take into account when evaluating the takeoff performance in a wet or

contaminated runway. For an overall description of the physical processes and regulatory

limitations that lead to the considerations in this sub-chapter see Appendix B – Performance on

Non-Dry Runways.

When it comes to runway condition, the takeoff performance will depend on the depth and type

of contaminant:

Contaminant Wet Contaminated

Water (fluid) < 3 mm 3 – 13 mm (1/2”) Slush (fluid) < 2 mm 2 – 13 mm (1/2”) Wet Snow (fluid) < 4 mm 4 – 25 mm (1”) Dry Snow (fluid) < 15 mm 15 – 25 mm (2”) Compacted Snow (hard) - all Ice (hard) - all

Table 8 - Wet and contaminated runways [15].

Contaminants can be divided into hard and fluid contaminants, which have a different effect on

aircraft performance [15]

Hard contaminants reduce friction forces;

Fluid contaminants reduce friction forces, cause precipitation drag and aquaplaning.

Also, as seen in the Table 8, the runway is considered either wet or contaminated, depending

on the type and depth of the contaminant.

This way, the performance software will consider the specific physical processes (friction forces,

aquaplaning and drags) that apply for each kind of contaminant, as it will account for the

particular regulations that apply for the corresponding runway state (wet or contaminated),

which may also differ from the dry runway condition.

When considering an all engines operating takeoff TOD, TOR and ASD are determined the

same way as described early in this chapter, whatever the runway condition. When accounting

for a one engine inoperative takeoff, however, TOD and TOR are calculated in a different way

[18]:

the use of reverse thrust credit is allowed for ASD determination;

the gross flight path starts at 15 feet.

4.5. Limitation Summary

All in all, the takeoff limitations, resulting from the the former definitions and regulatory

constraints that were presented throughout this chapter can be summarized the following way

(Figure 30 and Table 9):

29

Figure 30 - Takeoff Performance Limitations.

The following table enumerates the resulting limitations:

Code Limitation

1 1st Segment

2 2nd

Segment 3 Runway 4 Obstacle 5 Tire Speed 6 Brake Energy 7 Maximum Weight 8 Final Takeoff 9 - - - - - -

VMU VMCG VMCA V1/VR Acceleration 3

rd Segment

Gross Level-off Height Turn Height

Table 9 - TAP’s takeoff limitations.

The first nine correspond to the original limitations set by Airbus’ official documentation, while

the remaining five are in agreement with the new TAP’s takeoff performance limitations table

(currently implemented in TAP’s EFB project).

30

5. Takeoff Optimization

This section covers the principle/methodology used to optimize the takeoff performance. The

optimization objective is to obtain the highest possible performance-limited takeoff weight –

Maximum Takeoff Weight (MTOW), while fulfilling all the airworthiness requirements seen in the

past sections [15] and, consequently, respecting all the limitations enumerated in the past Table

9 - TAP’s takeoff limitations.

It is necessary to determine which parameters influencing the takeoff (influencing the

limitations) are fixed – Sustained Parameters (cannot be changed) and which offer freedom of

choice – Free Parameters. For instance, the current wind condition cannot be changed or

chosen – this is a sustained parameter.

The influencing parameters are enumerated in the table below.

Sustained Parameters Free Parameters Runway TORA

TODA ASDA Lineup Adjustments Slope Condition

Flaps Setting Air Conditioning V1/VR Ratio V2/VS Ratio

Outside Elements

Wind Pressure Outside Air Temperature

Obstacles and Takeoff Trajectory

Anti-Ice

Aircraft Status (MEL/CDL)

Table 10 - Influencing Parameters (adapted from [15] and [18]).

As seen in the Aircraft Performance chapter, both the chosen flap setting and the engine bleeds

condition take major impact in the aircraft performance, and consequently in the takeoff

performance.

Nevertheless the takeoff speeds represent the most important source of optimization and

MTOW gain [15] [24]. This way, “at a given configuration (and all sustained parameters), takeoff

weight limitations are set as functions of V1/VR and V2/VS” [18].

5.1. Optimization Range

Assuming a given aircraft condition, the takeoff optimization process will take place inside a well

delimited range defined by the maximum and minimum allowed values for both speed ratios.

a) V1/VR Range

As mentioned in chapter 3, the decision speed, V1, must always be less than the rotation speed,

VR. Although VR depends on the weight and the value of V1 is not fixed, the maximum V1/VR

ratio is equal to one (V1/VR 1) [15].

31

Also, the minimum V1/VR ratio is equal to 0.84 (manufacturer value [15]). This way, one can say

that the V1/VR ratio has a well-defined range:

(16)

This proves to be particularly useful since it also grants a well-defined range for the takeoff

optimization process.

“Any V1/VR increase (resp. decrease) should be considered to have the same effect on takeoff

performance as a V1 increase (resp. decrease)” [15, p. 193].

b) V2/VS Range

As seen in chapter 6, the minimum value for V2 imposed for Airbus’ Fly-By-Wire aircraft (all of

TAP’s fleet) is 1.13VS1g. Although V2 does not have a fixed value (since the stall speed depends

on the aircraft weight), the V2/VS ratio is known for a given aircraft type.

This way, having a well-known range, the V2/VS ratio proves to be very helpful for the takeoff

optimization process:

(17)

A maximum value for V2 (and consequently, a maximum V2/VS) is specified by the manufacturer

(see table below), which corresponds to an optimal V2.

Aircraft Family V2/VS range

A320 1.35 1.13 ≤ V2/VS ≤ 1.35

A330 1.40 1.13 ≤ V2/VS ≤ 1.40

A340 1.45 1.13 ≤ V2/VS ≤ 1.45

Table 11 - V2/VS maximum values for the Airbus family (data retrieved from [15]).

“Any V2/VS increase (resp. decrease) should be considered to have the same effect on takeoff

performance as a V2 increase (resp. decrease)” [15, p. 194].

5.2. Free Parameters Influence

This is one of the most significant sections of the present work since it will allow the reader to

understand in detail the variables of the takeoff optimization and this way get a clear picture of

how the weight optimization is actually performed.

a) Flaps Setting

Currently all of TAP’s aircraft have three distinct sets of flaps and slats configurations that are

specially designed for the takeoff procedure: Configuration 1+F, Configuration 2 and

Configuration 3 [14].

Each of these configurations is associated with a set of certified performance, making it suitable

for one specific situation but inappropriate for another (e.g. shorter/longer runway). On account

of this, “the optimum configuration is the one that provides the highest MTOW” [15]. As a

general rule, this is the chosen configuration.

However there are some exceptions, take for example situations that may result in a loss of

comfort by the passengers or that are prone to a tail strike event (e.g. using Configuration 1+F

on extensive runways for long aircraft as the A340) [24] [20]).

32

The takeoff configuration selection also affects the FLEX temperature and consequently the

level of necessary thrust [24]. This will be the focus of attention at the end of the current

chapter.

As a general rule, Configuration 1+F offers better aircraft performance on long runways (better

climb gradients), whereas Configuration 3 provides better performance on short runways

(smaller takeoff distances). Sometimes, other parameters, such as obstacles, can interfere. In

this case, a compromise between climb and runway performance is required, making

Configuration 2 the optimum configuration during takeoff [15].

The resulting takeoff distances and gradients achieved by the different configurations are

illustrated in the subsequent figure:

Figure 31 - Takeoff configurations performance (adapted form [15]).

b) Air Conditioning

Having the air conditioning switched on during takeoff results in a loss of power and

consequently degrades the takeoff performance.

c) V1/VR Ratio

As the purpose of this sub-section is to analyze the impact of V1/VR ratio variation on the aircraft

weight limitations, the V2/VS ratio will be considered a fixed parameter.

Figure 32 translates the influence of the V1/VR ratio on the MTOW, limited by the runway

limitations.

Figure 32 - Runway Limited MTOW (adapted from [15]).

A higher V1/VR ratio (or a higher V1) leads to a higher percentage of the acceleration phase with

all engines operating (remember that despite the value that V1 will take, the engine failure is

33

assumed one second before it is achieved), consequently, it will take less time (and distance) to

achieve V2 at 35 ft. This translates in less restrictive TODOEI and TOROEI limitations. On the

contrary, TODAEO and TORAEO are independent of V1 as there is no engine failure, and thus no

consequence on the acceleration phase and the necessary distance to reach 35 ft. As for the

ASD, it will grow more limiting as V1 increases, since a longer part of the runway is covered

during both the acceleration and the braking phases [15].

Figure 33-a translates the influence of V1 on the climb and obstacle limited MTOW, while Figure

33-b shows its effect on the tire speed and brake energy weight limitations.

Figure 33 – Effect of V2/VS in the (a) obstacles, takeoff segments, (b) brake energy and tire speed

limitations (adapted from [15]).

The V1 speed has no direct influence on climb gradients and consequently on the 1st, 2

nd and

final segment gradients. However, as the takeoff distance is reduced (for higher values of V1),

the obstacle-limited weights are improved since the aircraft requires a lower gradient to clear

the obstacles [15]. “A maximum V1 speed, limited by brake energy (VMBE), exists for each TOW,

this is why it seems to grow more limiting as V1 increases. To achieve a higher V1 speed, it is

necessary to reduce TOW” [15]. V1 has no influence on the tire speed limitation.

Taking into account the preceding limitations it is possible to find the optimal V1/VR which

corresponds to the MTOW for a specific V2/VS ratio:

Figure 34- Optimum V1/VR [15].

34

d) V2/VS Ratio

In a similar way to the previous sub-section, the V1/VR ratio will now be considered as a fixed

parameter this way allowing to study the influence of the V2/VS ratio on the MTOW limitations.

As a general rule, for a given V1/VR ratio, any increase in the V2/VS ratio translates as an

increase of the takeoff distance (both all-engine-operating and one-engine-out). This reflects the

need to acquire more energy (speed) on the runway in order to achieve a higher V2 speed at 35

feet. Consequently the acceleration phase is longer and the 2nd

segment slope increases [15].

Although the V2/VS ratio does not influence directly the ASD, a higher ratio leads to an increase

in VR which demands a higher V1 (for a given V1/VR) and outcomes in a higher ASD. The

resulting increase in V1 translates as a reduction of the weight by the brake energy and tire

speed limitations (see Figure 33-b) [15].

Additionally, any V2/VS increase results in higher climb gradients and consequently in less

restrictive 1st and 2

nd segment gradient limitations. It does not influence, however, the final

takeoff gradient since this is flown at green dot speed.

V2 does not have a direct impact on the brake energy limitation. Nevertheless any increase in V2

demands an increase in V1, and consequently on VR as well (assuming a fixed V1/VR ratio)

which results in a more restrictive brake energy limitation.

Table 12 summarizes all the previous conclusions on the influence of V2/VR in the MTOW

limitations.

(Assuming a fixed V1/VR) When V2/VS Increases

Limitation Length/Clearance/Climb gradient/Speed/Energy

Weight limited by

ASDA ↗ ↘

TORA/TODA ↗ ↘

Close Obstacle ↘ ↘

Distant Obstacle ↗ ↗

1st Segment Gradient ↗ ↗

2nd

Segment Gradient ↗ ↗

Final Segment Gradient - -

Tire Speed ↗ ↘

Brake Energy - ↘

Table 12 - Influence of V2/VS ratio on takeoff limitations [25].

5.3. Optimization Process

“The Regulatory Take-Off Weight and associated takeoff speeds (...) are determined through an

iterative process which looks for the optimum V1/VR for a given V2/VS and then for the

optimum V2/VS for that V1/VR” [25]. The process continues until the difference between two

subsequent iterations is less than, or equal to, the specified precision.

The following figure shows a spatial representation of the variation of MTOW with both speed

ratios, for a given set of sustained parameters and aircraft configuration:

35

Figure 35- MTOW as function of V1/VR and V2/VS [25].

It is possible that under certain conditions the optimization results in a range of optimum

solutions, instead of a single maximum:

Figure 36 – Range of soultions that maximize MTOW (adapted from [25]).

Once the optimum speed ratios (V1/VR and V2/VS) are obtained, the takeoff speeds are obtained

as follows:

Figure 37 - Takeoff speeds calculation [26].

AFM means that the information is obtained from the Aircraft Flight Manual (AFM).

36

5.4. Flexible Takeoff

Although flexible temperature calculation is beyond the scope of the current work since it can

only occur moments before an aircraft takes-off, there are some flex related parameters that

should be provided in the RTOW chart such as the maximum flexible temperature (TFlex Max) and

the reference temperature (TREF). This sub-chapter describes the maximum flexible temperature

while introducing the concept and relevance of the flexible takeoff.

“A takeoff at reduced thrust is called a flexible takeoff, and the corresponding thrust is called

flexible thrust” [15, p. 87]. When the actual takeoff weight (ATOW) is lower than MTOW, takeoff

may be performed with less than the maximum takeoff thrust (TOGA) (see Appendix A2 – 25-15

4(c) for more regulatory information) [18].

Recalling that engine thrust drops when OAT increases, if ATOW is less than MTOW it is

possible to determine the temperature at which the needed thrust would be the maximum thrust

for this temperature – see Figure 37. “This temperature is called flexible temperature (TFlex) or

assumed temperature” [15, p. 87].

Figure 38 - Flexible temperature principle [15].

“Consequently, the flexible temperature is the input parameter through which the engine

monitoring computer adapts the thrust to the actual takeoff weight. This method is derived from

the approved maximum takeoff thrust rating, and thus uses the same certified minimum control

speeds” [15, p. 88], consequently complete aircraft performance data is available. Not only the

thrust reduction may never be more than 25% below the maximum takeoff thrust, but also must

be assured that TOGA speed may be applied at any time (AMJ – 25-15 (a)).

Therefore, a flexible takeoff may only be performed when the following conditions are

respected:

(18)

(19)

(20)

Additionally, flexible takeoffs are not allowed on contaminated runways and should not be

performed when wind shear is expected [24]. They may, however, be performed on wet

runways when the required performance information is provided (Airbus operational

37

documentation including the RTOW and FCOM – see Appendix A1 – AMJ 25-13, paragraph

(f)). “Takeoff at reduced thrust is only allowed with any inoperative item affecting the

performance, if the associated performance shortfall has been applied to meet all performance

requirements at the takeoff weight, with the operating engines at the thrust available for the flex

temperature” [21].

Performing the thrust reduction resulting from a flexible takeoff will save engine life [27], reduce

maintenance costs and improve engine reliability [18] [24]. As a result it improves both safety

and reduces operational costs.

38

6. Landing Performance

To dispatch an aircraft, an operator has to verify landing requirements based on aircraft

certification (JAR 25) and on operational constraints defined in JAR-OPS [15]. In normal

conditions, these requirements are not very restrictive and most times aircraft are dispatched at

their maximum structural landing weight (MLW). This leads to a minimization of importance of

landing checks during dispatch. However, landing performance can be drastically affected when

considering missing and/or inoperative aircraft items, under adverse external conditions and in

the presence of a contaminated runway. This way, landing performance checks are of utmost

importance and should always be taken into consideration to ensure a safe flight.

6.1. Operational Speeds

a) Lowest Selectable Speed (VLS)

As a general rule, during landing, pilots have to maintain a stabilized approach with a calibrated

airspeed of no less than VLS down to a height of 50 feet above the destination airport. VLS is

defined as 1.23 Vs1g of the actual configuration (for fly-by-wire aircraft) [15]:

(21)

b) Final Approach Speed (VFA)

The final approach speed, or VFA, is the aircraft speed during landing, 50 feet above the runway

surface. The flaps/slats are in landing configuration, and the landing gears are extended.

VFA is defined as [28]:

VLS for manual landing;

VLS + 5 kt for CAT II/CAT III automatic landing13

.

c) Reference Speed (VREF)

This speed is used as reference for emergency in flight performance computations when a

certain abnormality, or system failure, is verified. VREF means the steady landing approach

speed at the 50 feet point for a configuration Full approach (reference configuration).

Consequently:

(22)

In case of a system failure affecting the landing performance, Airbus operational documentation

indicates the correction to be applied to VREF to take into account the failure:

(23)

13

Auto-thrust is used or to compensate for ice accretion on the wings [15].

39

6.2. Runway

6.2.1. Landing Distance Available (LDA)

When no obstacle exists under the landing path the landing distance available is equal to TORA

[15], otherwise this distance must be shortened by defining a threshold considering a 2%

tangential to the most penalizing obstacle plus a 60 m margin (Figure 39).

Figure 39 - Obstacle influence on LDA [15].

In this case, the Landing Distance Available (LDA) is equal to the length measured from the

displaced threshold to the end of the runway.

This value is specified for each runway.

6.2.2. Actual Landing Distance (ALD)

a) Manual Landing

The actual landing distance is the distance measured between a point 50 ft above the runway

threshold and the point where the complete stop of the aircraft is achieved (see Figure 40) [28].

Figure 40 - Actual Landing Distance [15].

It is assumed that [28]:

The approach speed is defined as in paragraph 6.1-b)

The pilot applies maximum braking with the antiskid system operational

The ground spoilers are operating

No reverser thrust credit is considered

40

As in the takeoff situation, landing distance data must include correction factors for no more

than 50% of the nominal wind components along the landing path opposite to the landing

direction, and no less than 150% of the nominal wind components along the landing path in the

landing direction [15].

b) Automatic Landing

For an automatic landing, and on a dry runway, ALD is defined as follows [15]:

(24)

Where Da is the airborne distance phase (see Figure 41) and Dg the distance covered during

the ground role phase (see Figure 42).

Figure 41 - Airborne phase for an automatic landing [15].

The airborne phase distance (Da) corresponds to the sum of d1 and d2 plus three times the

standard deviation of d2, where d1 is the distance from the runway threshold up to the

glideslope origin and d2 is the distance between the origin and the mean touchdown point. The

standard deviation has been statistically established from the results of more than one

thousand simulated automatic landings [15].

Figure 42 - Ground role phase for an automatic landing [15].

The ground phase (Dg) for an automatic landing is established the same way as for the manual

landing, assuming a touchdown speed equal to the mean touchdown speed (VTD) plus three

times the standard deviation of this speed ( ) [15].

6.2.3. Required Landing Distance (RLD)

The Required Landing Distance (RLD) is deduced from the demonstrated ALD by applying a

margin coefficient that depends on the runway state, the type of landing (manual or automatic)

and the regulation [29]. Before departure, operators must check that the LDA at destination is at

least equal to the Required Landing Distance (RLD) for the forecasted landing weight and

conditions:

(25)

41

It is assumed that the aircraft will land on the most favorable runway, considering the probable

wind speed, direction and other conditions such as landing aids and terrain (JAR-OPS 1.515

(c)). Operators must take into account the runway slope, when its value is greater than ± 2%,

otherwise, it is considered to be null [15].

In the event of an aircraft system failure prior to takeoff, RLD is equal to the RLD without failure

multiplied by the coefficient given in the MEL, or to the performance with failure given by the

Flight Manual [15].

a) Manual Landing

For manual landing, regulation defines the required landing distances as the actual landing

distance divided by 0.6, assuming the surface is dry:

(26)

If the surface is wet, the required landing distance must be at least 115% of that for a dry

surface [28]:

(27)

For contaminated runways, the required landing distance must be 115% of the landing distance

determined in accordance with approved contaminated runway distance data (ALD for

contaminated runway) and greater than the required for the wet condition:

{ } (28)

For contaminated runways, the manufacturer must provide landing performance for speed V at

50 feet above the airport, such that [15]:

(29)

In certain contaminated runway cases, the manufacturer can provide detailed instructions such

as those on the use of antiskid, reversers, airbrakes, or spoilers. And, in the most critical cases,

landing can be prohibited [15].

b) Automatic Landing

As for the automatic landing case, according to regulation the required landing distance is

defined as the actual landing distance (ALD) in automatic landing multiplied by 1.15. This

distance must be retained for automatic landing whenever it is greater than the required landing

distance in manual mode [28]:

{ }

6.2.4. Runway Slope

A positive slope increases the aircraft stopping capability and consequently produces a

decrease in the landing distance. A downward slope results in the opposite, increasing the

landing distance [15].

42

6.3. Go-Around Requirements

6.3.1. Aircraft Certification

a) Approach Climb

The approach climb corresponds to an aircraft’s climb capability, assuming that one engine is

inoperative, and considering the following approach configuration (JAR 25.121):

Configuration 2 or 3 (for Airbus FBW aircraft)14

One-Engine-Inoperative

TOGA thrust

Gear retracted

1.23 Vs1g ≤ V ≤ 1.41 Vs1g

V > VMCL

Notice that an approach configuration can be selected, as long as resulting stall speed does not

exceed 110% of VS1g of the related “all-engines-operating“ landing configuration.

Under these circumstances the following minimum climb gradients must be demonstrated:

Nº of Engines Approach Climb

Minimum Climb Gradient (OEI)

Twin 2.1 % Quad 2.7 %

Table 13 - Minimum climb gradients during approach climb (OEI) [15].

b) Landing Climb

The landing climb constraint ensures an aircraft’s climb capability in case of a missed approach

with all engines operating, assuming the landing configuration (JAR 25.119).

Landing configuration [15]:

Configuration 3 or Full (for Airbus FBW aircraft)

All engines operating

Thrust available 8 seconds after initiation of thrust control movement from minimum

flight idle to TOGA thrust

Gear extended

1.13 Vs1g ≤ V ≤ 1.23 Vs1g

V ≥ VMCL

Under these conditions, the minimum gradient to be demonstrated is 3.2% for all aircraft types.

6.3.2. Performance Limitation

When for some reason the pilot rejects a landing (while within the decision height) he must

perform the Missed Approach (see dashed blue line in Appendix D) or the Go-Around

procedure. In the later, the aircraft climbs into the go-around circuit (Figure 43), maneuvering

into position for a new approach and landing [30].

14

for landing in configuration 3 or Full, respectively

43

Figure 43- Go-around procedure [15].

A minimum climb gradient must be observed in case of a go-around. The minimum climb

gradients may depend on the aircraft type and are subject to runway specifications. The go-

around performance encompasses the Approach Climb Gradient (ACG) and the Landing Climb

Gradient (LCG) limitations [29].

a) Approach Climb Gradient (ACG)

The landing climb minimum gradient never results in a performance limitation [29],

consequently, “during dispatch, only the approach climb gradient needs to be checked, as this

is the limiting one” [15, p. 123]. TAP only operates landings of CAT II approach types, in which

the minimum climb gradient is 2.5% (for all aircraft types), or greater if the approach charts

require a higher value for obstacle consideration (JAR-OPS 1.510 (a)).

For example, for runway 21R of OR Tambo International Airport (Johannesburg) there are

various go-around procedures with different minimum climb gradients (2.5, 3.7 and 5.1%) – see

APPENDIX D – FAJS-21R.

6.4. Outside Elements

a) Pressure Altitude

Approach speed is equal to 1.23 Vs1g. But, the corresponding TAS increases with the pressure

altitude [15]. Consequently, the landing distance will also increase.

Additionally, as seen before, TOGA thrust decreases with altitude, therefore, in the event of a

go-around, a decrease in engine thrust implies a decrease in the air climb gradients.

Summing up:

Figure 44 - Pressure altitude influence in the landing performance [15].

b) Outside Air Temperature

As seen before, in chapter 3.2.5, engine thrust decreases with temperature, when past the

reference temperature. Therefore, the air climb gradients imposed in the go-around procedure

will decrease.

44

c) Runway Condition

The definition of runway conditions is the same as for takeoff (see chapter 4.4.4). When the

runway is contaminated, landing performance is affected by the runway’s friction coefficient, and

the precipitation drag due to contaminants. A more detailed description of the physical

processes involved can be seen in APPENDIX B – Performance on Wet and Contaminated

Runways.

6.5. Limitation Summary

In conclusion, the landing limitations resulting from the all the former definitions and regulatory

constraints, which were presented throughout this chapter, can be summarized in the following

table:

Code Limitation

1 Structural Weight 2 LDA 3 Approach Climb 4 Landing Climb 5 Tire Speed 6 Brake Energy

Table 14 – Landing limitations [26].

45

7. Takeoff and Landing Performance

Application (TLP)

This section focuses directly on the computational application that was developed during the

present work. Notice that this chapter does not intend to replace the user’s manual15

for the TLP

application. Instead, the author will focus on the application structure, databases and the

OCTOPUS program, which is responsible for all the performance calculations.

7.1. Structure

The following diagram illustrates the relations between TLP and all the external agents (user,

OCTOPUS program and databases):

Figure 45 - TLP structure.

The TLP application uses two databases, the LPCAirport and LPCAirportAdd. The OCTOPUS

program has its own set of databases which include aircraft data, CDL data, and neuronal

networks.

TLP runs in a single windows process and mainly in a single thread as well, whose main

purpose is handling the user interface. It launches, however, additional short duration threads to

15

TLP’s user’s manual was supplied directly to TAP Portugal and is completely independent of the present work.

46

display a “Please Wait” animated message (see Figure 46) when it is busy (either loading data

or waiting for OCTOPUS to complete its calculations in the background).

Figure 46 - “Please Wait” animated message running in an additional thread.

TLP executes in two different modes: Takeoff Optimization and Landing Optimization (Figure

47). As seen in chapter 5, the main purpose of the first mode is to optimize the takeoff weight

(as a function of the sustained and the free parameters) and this way calculate MTOW and the

resulting operational takeoff speeds (V1, VR and V2). In a similar way, as seen in chapter 7, the

objective of the Landing Optimization mode is to calculate the MLW, the landing distances

(required and actual) and the approach speed.

Figure 47 - TLP on startup.

TLP’s user interface (Figure 48) consists in several visual basic forms that contain a series of

controls (such as buttons, combo boxes, text inputs and check boxes) with which the user

interacts, and this way configure the free and sustained parameters. The parameters are

temporarily stored into visual basic classes and are later written to the OCTOPUS input file (see

Appendix C1 (a)) so that they can be used as input for the optimization process.

The OCTOPUS program is launched and ran in the background as an independent program

through the windows shell function. In the meantime the TLP process stalls, launching a “Please

Wait” message in a new thread (Figure 46), while waiting for the OCTOPUS program to

successfully terminate its execution. The OCTOPUS program concludes its activity by writing an

output file (see Appendix C1 (b)) with the results of the optimization.

This output file is then loaded and parsed by the TLP program, presented to the user and is now

ready to be exported as a real RTOW chart (see Appendix C1 (c)). The user can readjust the

parameters and perform new optimizations at his will.

47

7.2. User Interface Overview

The following figure shows the main form of TLP application. It comprises four tabs that allow

switching between different pages, each one addressing a specific topic of configurable

parameters. The first page targets the selection of the aircraft model (by model, plate or name)

and its parameters:

Figure 48 – Aircraft page for the Takeoff Optimization mode.

Pressing the “Edit” button on the “Failures” panel shows a new auxiliary form, the aircraft

failures form (Figure 49), which will allow the user to configure the missing and inoperative

aircraft items (MEL and CDL items).

Figure 49 - Aircraft Failures form.

The second page, the Runway tab (Figure 50), addresses the selection of the airport, respective

runway and all the outside elements as well (pressure, wind and runway condition).

48

Figure 50 – Runway page for the Takeoff Optimization mode.

The Options page contains regulatory configurable parameters (Figure 51), such as the

minimum level-off height that by default is set to 1500 ft (according to TAP’s policy) but can be

reduced down to 400 ft (according to regulation). As an advanced option, the calculation mode

combo box allows exchanging between First Principle and Polynomial methods. The first is

more precise and time consuming, while the second is faster but more conservative. The page

also displays information about the current lineup allowances (not editable).

Figure 51 - Options page for the Takeoff Optimization mode.

Last but not least, the Calculation page (Figure 52) is where the user specifies the temperature

vector to be optimized. The page also displays a summary of the most important parameters,

allowing a quick checkup before executing the calculation by pressing the “Run” button.

49

Figure 52 - Calculation page for the Takeoff Optimization mode.

For the takeoff optimization, the temperature vector consists of two sections separated by the

aircraft engines reference temperature (TREF). Above this temperature the aircraft performance

changes considerably with temperature (as seen in chapter 5) so it is expected to desire a

smaller step between consecutive points. The number of points in the first section is directly

specified by the user. By default, the program sets the initial and last points of the second

section to the first integer above TREF and TFlex Max, respectively.

The following scheme illustrates the structure of the temperature vector, describing how it is

internally calculated:

Temperature Vector

Fir

st S

ecti

on

Points before reference temperature

TREF – NBefore x step1

step1 (…)

TREF – step1

Seco

nd

Sec

tio

n

Points between reference and maximum flex temperature

TREF

step2

TREF + step2

(…)

TFlex Max – step2

TFlex Max

Figure 53 - Temperature vector.

For the landing optimization the temperature vector is much simpler, it is only defined by the first

and last point plus the precision step.

Finally, after OCTOPUS concludes its operation, the output is presented in the Output form:

50

Figure 54 - TLP’s Output for the Takeoff Optimization mode.

Here, the optimization results can be exported as a PDF file (see TLP – Takeoff Optimization

Output), an Excel file or even printed. The user can close the Output form, readjust the

parameters and perform new optimizations at will.

7.3. Databases and Internal Classes

TLP uses the LPCAirport and LPCAirportAdd databases to acquire most of its information. They

contain all the required information on TAP’s aircraft and respective systems, as well on all the

airports, and respective runways, with which TAP currently has (or had) ongoing operations.

Both of them are external Microsoft Access databases, thus data maintenance is very simple

and does not require further recompilation of the program. TLP takes advantage of the OLE DB

(Object Linking and Embedding, Database) API to access both of these databases.

LPCAirport is a Microsoft Access database built and maintained by TAP Portugal. Besides TLP

there are other programs and projects that currently use this database (namely TAP’s EFB

project). Unfortunately its inherent massive size forbids the attachment of any kind of diagram

that could properly represent the database.

The LPCAirportAdd database was built during the development of the current work with the

purpose of complementing the LPCAirport databse, adding specific on aircraft’s gears and

operational limits. It is expected that both databases will be fused together in the future.

The takeoff (or landing) parameters, selected by the user, are internally stored and organized in

a set of visual basic variables and classes. The most relevant are the Aircraft and Airport

classes, together with their respective subclasses which can be seen in the Appendix C2 –

Visual Basic Classes (a) and (b).

Notice that OCTOPUS databases are addressed later in this chapter.

7.4. Relevant Routines

Although the program contains innumerous functions making it impossible to enumerate and

describe every single one, there are some functions of special relevancy that will be addressed

in this sub-chapter.

51

7.4.1. ISA Temperature calculation

It was necessary to compute the ISA (International Standard Atmosphere) temperature as a

function of the pressure altitude. For that purpose, the tISA function (see Appendix C3 (a))

implements the following method [9]:

[°C] (21)

Where h is the pressure altitude in feet.

7.4.2. Pressure Altitude Conversion

Pressure altitude “is the altitude corresponding to a value of atmospheric pressure” (see Figure

55) [9, pp. 4-9]. In aeronautics, it is a common practice to use the pressure altitude as a

measure of altitude since the atmospheric pressure can be read by a simple pressure altimeter

(which can be found in most aircraft). The pressure altimeter must be calibrated to the local

altitude conversion (QNH), so that it reads the altitude above MSL.

Figure 55 - Pressure Altitude function of Pressure.

Consequently, it was necessary to implement functions that could calculate the standard

pressure at a given altitude (pa2p – see Appendix C3 (b)), and vice-versa (p2pa – see Appendix

C3 (c)). It was assumed ISA conditions for the temperature and that air is a perfect gas.

They were based on the following equations, for altitudes inside the troposphere (above MSL

and below 36.089 ft) [15]:

(

)

[hPa] (22)

(

)

[m] (23)

With:

P0 = 1013.25 hPa (standard atmosphere at MSL)

T0 = 288.15 K (standard temperature at MSL) g0 = 9.80665 m.s-2 (standard gravity at MSL) R = 287.053 J.Kg-1.K-1 (Perfect gas constant)

52

7.4.3. TFlex Max, TMAX and TREF Calculation

TFlex Max, TMAX and TREF are always presented in RTOW charts and consequently must be

calculated by TLP as well. Since they are not computed by OCTOPUS, TLP has to calculate

them internally. This task is performed by a simple function – SetInitialTemperature (see

Appendix C3 (d)).

The LPCAirport database provides the TFlex Max for each aircraft at MSL (Mean Sea Level) and

assuming ISA conditions. Additionally, it also provides the necessary coefficients to estimate the

TFlex Max, TMAX and TREF as functions of the pressure altitude. Note that temperature changes with

pressure altitude are roughly linear, so it can be estimated the following way:

(24)

Where x is the pressure altitude and a and b are the respective temperature coefficients

(provided by the LPCAirport database for each aircraft).

This way, it is possible to calculate the TFlex Max with those coefficients and then calculate the

temperature correction by subtracting one from another. This correction can then be used to

correct TMAX and TREF as well, since they were estimated using the same (linear) process.

7.5. OCTOPUS

This sub-section focuses on OCTOPUS, the program responsible for all the calculations in TLP.

OCTOPUS stands for Operational and Certified TakeOff and landing Performance Universal

Software. This is an Airbus program that is able to compute aircraft performance calculations

under regulatory constraints, and this way is able to optimize takeoff and landing performance

for given runways. OCTOPUS is used for computations related to A318, A319, A320, A321,

A330, A340 and A380 aircraft [26]. It was delivered by Airbus in the form of Fortran 95 source

code with roughly 230000 lines of code and later compiled during this work by the Compaq

Visual Fortran 6 compiler.

7.5.1. Structure

OCTOPUS comprises a set of executable files, databases and temporary files:

Figure 56 - OCTOPUS Structure.

OCTOPUS uses specific a large group of files that contain various aircraft data (such as

speeds). These aircraft databases are called OCTOBASE. The Neural database consists of a

53

set of neural files containing pre-computed data which can be used to initiate the calculation

process. Performance penalties coming from CDL items are obtained from the CDL database.

The following table enumerates all of TAP’s aircraft models and their respective databases:

Aircraft Model Database Neural Database

A319-111 AD111C02 XD111C02.PRE A319-112 AD112E01 XD112E01.PRE A320-211 AE211C03 XE211C03.PRE A320-214 AE214B02 XE214B02.PRE A321-211 AC211B05 XC211B05.PRE A330-202 AB202C02 XB202C02.PRE A330-223 AB223A03 XB223A03.PRE A340-312 AA312B04 XA312B04.PRE

Table 15 - Aircraft models and respective databases.

7.5.2. Functions

OCTOPUS functions can be split in three categories (Figure 57): Aircraft data file consultations

and Flight manual calculations, which are certified and Optimizations (takeoff and landing)

which use regulatory calculation but which are not certified [26].

Figure 57 - OCTOPUS Functions.

TLP only uses functions from the third group, specifically the Takeoff Optimizations and the

Landing Optimizations functions. The Takeoff Optimizations may be performed in the point,

curve, network or chart modes, while the Landing Optimizations can only be executed in point

and chart.

In the point computation mode, OCTOPUS optimizes the takeoff weight for a specific set of

conditions. For curve and network modes, however, it is possible to set a group, or two, of

additional conditions to be optimized (such as a temperature vector, and/or different wind

conditions). The aim of the chart computation mode is to build a complete RTOW chart, and in

the same way as the curve and network modes, also allows specifying additional groups of

conditions [26].

Since TLP’s goal is to optimize the aircraft performance under a specific set of conditions, and

for a certain temperature vector: for the takeoff optimization mode the curve computation is

adequate, while for the landing optimization it was necessary to implement a chart computation.

54

7.5.3. Calculation Methods

The program has two optimization methods: first principle and polynomial methods. The first is

based on classical equation resolution, hence several computations are made by integration of

equations. Consequently, it is the most accurate method but also the most time-consuming.

Instead, the polynomial method, being a derivative mode of the previous one, is faster but more

conservative. The performance constraints are smoothed by polynomials and in certain cases a

quick estimation of weight and V2 is given by a neural network (stored in specific neural files).

Polynomial coefficients are also stored in specific files, together with aircraft databases [26].

“Airbus strongly recommends the use of the first principle mode to compute weight optimization

for accurate calculations” [26].

The polynomial method cannot be used in the following conditions [26]:

runway slope greater than 1 %

pressure altitude greater than 8500 ft

landing gear extended

turn

three engine ferry flight

TORA, TODA or ASDA length greater than 5000 m and lower than 2000m for A330,

A340 and A380 aircraft and lower than 1700m for A318, A319, A320 and A321 aircraft.

extended second segment

CDL items

combination of failure cases

7.6. Testing and Validation

With the purpose of validating the developed software, TLP was subjected to extensive testing.

Its output and corresponding RTOW charts were compared to TAP’s existing charts, for a

multitude of input conditions (different aircraft, runways and other parameters). Additionally,

they were also compared to the results obtained by the TLO module (Takeoff and Landing

Optimization) of Airbus’ official performance program for windows – PEP (Performance

Engineer’s Programs).

A computational methodology was developed specifically for this purpose: TLP’s and TLO’s

outputs were automatically exported to an Excel worksheet and compared (see Sample Excel

File produced during TLP validation. TLP did not fail even once.

7.6.1. Validation by Certified Software

Taking into account that TLO module is not certified, an additional analysis was required. This

way, this study aims at demonstrating that the results obtained with TLP, for the takeoff and

landing performance optimizations, comply with AFM, a certified performance software module

of PEP. Since a full demonstration for all the aircraft models in TAP fleet would be too extensive

to fit the requirements of the present work, this methodology will only be applied to a single

aircraft model: the Airbus A330-202.

a) Takeoff

According to the Flight Manual of this aircraft model (see APPENDIX E – FM Page - A330-202),

its certified performance is produced by the program module “Performance Engineer’s

55

Programs / AFM_OCTO approved FM module”, with the database AB202C02 or AB202C03, in

the PC version of the program Octopus 23.0 or higher. The Takeoff Performance calculation in

TLP uses the Airbus calculation program OCTOPUS version 27.0.1 and database AB202C02,

for this aircraft model (see Table 15, on page 53).

A number of runways were selected as representative of the operation of this aircraft, under

different conditions of use that address various atmospheric conditions (temperature, pressure,

runway condition - dry, wet, contaminated), or MEL items. This is the same methodology that is

currently being used by TAP in the demonstration of TAP’s Type B EFB Software - Takeoff

Performance Calculation Module.

The following table summarizes the values obtained with TLP’s takeoff performance

optimization for the different runways and conditions (see TLP – Takeoff Optimization Output,

for the RTOW chart produced by TLP for the first case in the table):

RWY Conf OAT (°C)

RWY Condition

QNH (hPa)

W/C (kt)

MTOW (ton)

V1 (kt)

VR (kt)

V2 (kt)

LIS 03 P1 1 + F 25 DRY 993.25 0 238 154 164 170

LIS 03 P1 1 + F 21 DRY 1003.25 -10 230 143 157 163

LIS 03 P1+ 1 + F 41 WET 993.25 +10 221 149 159 164

LIS21*+ 1 + F 39 WET 993.25 0 228 143 157 162

EWR 04L 2 2 Slush ¼” 1013.25 0 235 143 149 154

EWR 04L 2 2 Cp. Snow 1013.25 0 245 154 160 166

JNB 03L 1 + F 7 DRY 1023.25 +10 227 152 163 168

JNB 03L 1 + F 33 DRY 1013.25 0 207 149 156 161

Entry angle – 90° in all cases Bold –Thrust with BUMP

16

*Spoilers – 2 Pairs INOP +All reversers INOP

Table 16- TLP’s takeoff optimization results.

RWY TORA (m) TODA (m) ASDA (m)

LIS 03 P1 3805 3905 3805

LIS21 3805 3905 3805

EWR 04L 3353 3353 3353

JNB 03L 4418 4688 4418

Table 17 - Selected runways’ lengths.

Using now the “Complete Takeoff” function of the certified FM module of PEP, the results for the

same conditions are the following, as detailed in Appendix F1 (only for the first situation):

RWY OAT (ºC)

TOR (m)

TOD (m)

ASD (m)

V1 (kt)

VR (kt)

V2 (kt)

Grad 2º Seg

Obst

LIS 03 P1 25 3556.7 3885.6 3414.1 153.595 163.810 169.441 2.939 OK

LIS 03 P1 21 3559.5 3881.3 3296.4 143.773 156.572 162.870 3.199 OK

LIS 03 P1+ 41 3442.0 3442.0 3755.8 149.474 158.582 163.591 2.727 OK

LIS21*+ 39 3636.3 3636.3 3755.3 143.416 156.515 161.994 2.400 OK

EWR 04L 2 2639.4 2639.4 3343.0 143.402 148.277 153.252 2.707 OK

EWR 04L 2 2786.7 2786.7 3306.8 154.333 159.753 165.718 2.831 OK

JNB 03L 7 3731.2 4055.4 3583.7 152.017 161.285 166.409 2.400 OK

JNB 03L 33 3797.4 4125.6 3836.7 149.154 155.826 160.390 2.401 OK

Table 18 – AFM’s takeoff results.

16

BUMP is an engine setting that allows additional thrust power at the cost of reducing engine life.

56

Notice that the FM module takes TOW, V1/VR and V2/VS as input, consequently these values

were obtained externally by PEP’s TLO module:

RWY OAT (ºC) V1/VR V2/VS TOW (ton)

LIS 03 P1 25 0.936 1.218 238857

LIS 03 P1 21 0.916 1.191 230814

LIS 03 P1+ 41 0.941 1.218 221812

LIS21*+ 39 0.914 1.191 228092

EWR 04L 2 0.966 1.174 235952

EWR 04L 2 0.965 1.243 245759

JNB 03L 7 0.935 1.233 227748

JNB 03L 33 0.956 1.232 207006

Table 19 - Optimum weights and ratios obtained by PEP’s TLO module.

Comparing the Table 17 with Table 18 it is found that the required runway lengths are lower

than those available.

Also, all the MTOW and V1 values calculated by TLP (in Table 16) are lower than the ones

obtained by the certified software (see Table 18). Notice that TLP rounds down to the unit the

values for both MTOW and V1 (rounds up VR and V2) internally so that a more conservative

result is deliberately produced. In a similar way all the values for VR and V2 computed by TLP

are higher, and more conservative, than the ones calculated by PEP’s certified module.

Finally, all the obstacle limitations were tested and verified as seen in Appendix F. The graphs

obtained show the obstacles and the 35 feet margin providing, this way, providing a visual

verification. To check this limitation, not included in the PEP’s FM module function “Complete

Takeoff”, use was made of the “Takeoff Flight Path” calculation option.

This demonstrates the consistency of the results obtained from all of the modules.

b) Landing

In a similar way, the results obtained in TLP for landing optimizations were also tested against

the results obtained by certified AFM software.

It was considered a hypothetic situation of an Airbus A320-202 landing in Johannesburg’s OR

Tambo International Airport on runway 03L. This particular runway has different go-around

procedures but it was assumed to consider one that required a minimum of 3.5 % for the

approach climb gradient (ACG). The aircraft was assumed to use configuration Full during

landing, configuration 3 for the approach and a low braking setting during ground roll.

The following table describes the atmospheric conditions for the considered landing and

summarizes the results obtained through TLP’s landing optimization:

RWY OAT (°C)

RWY Condition

QNH (hPa)

W/C (kt)

MLW (ton)

VFA (kt)

ALD (m)

RLD (m)

JNB 03L 3 Slush ¼” 1013.25 10 186.0 137 2285 2482

Table 20 - TLP landing optimization results.

Like in most landing situations, the minimum approach climb gradient is the weight limiting

restriction, as seen in the complete output file produced by TLP, that can be seen in Appendix

C1 (d).

Unlike for the takeoff situation, PEP’s FM module does not have a full landing calculation

function, instead, it was necessary to use a set of different functions: Approach Climb Gradient,

Landing Climb Gradient, Landing Distance and Operational Landing Distance.

57

The Landing Distance function takes MLW as input and outputs the required landing distance

imposed by regulation, which as seen in table 21 is equal to the value computed by TLP:

MLW (ton) RLD (m) Computed LD (m) VFA (kt)

186.0 2482.0 2158.2 137.333

Table 21 – Required Landing Distance calculated by FM’s Landing Distance function.

Notice that both required landing distances are below 4418 m which is the landing distance

available (LDA) for the runway 03L (see Appendix C1 (d)). The complete output file produced by

the Landing Distance function can be seen in Appendix G1.

According to Table 22 the actual landing distance computed by FM’s Operational Landing

Distance function is also below the one obtained by TLP. Additionally, since the approach

speed obtained by TLP is lower than the one obtained by both FM’s landing distance functions,

it is also more conservative than the one calculated by PEP’s FM module. For the complete

Operational Landing Distance output file, see Appendix G2.

MLW (ton) ALD (m) VFA (kt)

186.0 2284.6 137.333

Table 22 - Actual Landing Distance calculated by FM’s Operational Landing Distance function.

The Landing Climb Gradient function accepts the minimum landing climb gradient as input, set

by regulations to 3.2 %, and outputs the maximum weight limited by LCG, among other

performance data (the complete output file can be seen in Appendix G3):

LCG Maximum Weight (kg) IAS (kt)

3.2 % 267227.2 165.218

Table 23 - Maximum weight calculated by FM’s Landing Climb Gradient function.

The Approach Climb Gradient function takes the minimum approach climb gradient as input

(which in this case is equal to 3.5 %) and outputs several performance data, namely the

maximum landing weight (the whole output file can be seen in Appendix G4):

ACG Maximum Weight (kg) IAS (kt)

3.5 % 186028.0 142.677

Table 24 – Maximum weight calculated by FM’s Approach Climb Gradient function.

Comparing the values from Table 23 and Table 24, we conclude that the weight limitation

imposed by the LCG condition is less restrictive than the one imposed by the ACG limitation,

consequently the MLW obtained by the certified software is 28 kg above the one computed by

TLP.

Concluding, TLP’s values are sound and are more conservative than the results obtained by the

certified software.

58

8. Conclusion

Motivated by the opportunity to provide real contribution to the aviation industry, and particularly

to TAP, it was with great enthusiasm that the author first started working on this project. It is with

a similar feeling in pair with the added sense of accomplishment that he writes these last lines

of the present dissertation.

Although the current work consisted in the development of a computational application, a large

initial effort was invested in the interpretation of the OCTOPUS program, namely its internal

procedures, functions, databases and specially its input and output files. Undoubtedly, this was

one of the most important and time-consuming stages of the dissertation; OCTOPUS is after all

the backbone of the TLP program.

Simultaneously, the author attended one of TAP’s internal Aircraft Performance courses which

proved to be of great value. It has provided not only valuable theoretical knowledge but also in

loco know-how on TAP’s own policy on takeoff and landing procedures.

Only later, when the program’s lifecycle, and consequent flowchart, became a comfort area to

the author, it took place the computational development. The user interface is the outcome of an

interactive process based on the experience and sensibility acquired from Airbus’ official

performance programs (PEP) of both TAP engineers and future users of this application.

The Takeoff and Landing Performance Program (TLP) is TAP’s new technological solution for

on-ground performance calculation. Besides providing valuable benefits for the dispatch

procedures, with its dynamic and prompt reaction user interface, it will prove to be a helpful

working tool for TAP’s performance engineers with its vast configurable inputs and editable

Excel worksheet outputs. One process that could take a couple of hours, before, can now be

accomplished within seconds, providing safe and always optimal values.

All in all, the author believes that the present project will prove its benefit to TAP Portugal, either

by simplifying the daily activity of its engineers or by serving as a new training tool for pilots.

This way, TLP places TAP one step further in the never-ending optimization process.

Computer performance data calculation in cockpits is the next step in airline industry [1]. Major

commercial companies have investigated the advantages of electronic computing devices in the

cockpit. In 2001 UAL (United Airlines) tested an EFB device incorporating a Fujitsu Pentablet

computer on an Airbus 319 aircraft with specially trained crewmembers. Since receiving a grant

from the FAA in September of 2001, UAL has been developing an EFB that may become a

standard for the industry [31]. Projects such as this and TAP’s Electronic Flight Bag are

currently pioneers in the struggle to develop certified EFBs.

Primarily, EFBs are used by commercial transport pilots for the performance of flight

management tasks, both during flight and in the aircraft turnaround. Currently, the range of

functionality supported includes aircraft performance calculations, weather and situation

displays, flight log reporting, aircraft defect reporting, communications and document viewing

(checklists, aeronautical charts and maintenance manuals) [32].

There are two distinct steps proposed by Airbus for implementing this idea into life [1]. The first

involves the implementation of out of the box technology low cost solutions, such as TAP’s EFB.

These take advantage of commercially available laptops, which can be plugged-in to the

aircraft’s cockpit. The next step would be server linking aircraft avionics and EFB systems,

allowing aircraft manual update, enhanced flight functions, and maintenance data transfer

through wireless gate-links at speeds 100 times faster than today’s Aircraft Communication and

Reporting System (ACARS) [33].

59

9. References

[1] I. Sikora, S. Pavlin and E. Bazijanac, "The Example of Laptop Based Performance Data

Generating and Optimization in Contemporary Commercial Aircraft Operations," in

ISEP'99, 1999.

[2] TAP, Guia de Integração de Estagiários, TAP, 2009.

[3] TAP, "TAP, S.A. obtém o Melhor Resultado de Sempre," Commercial Airliner, 10 March

2010. [Online]. Available: http://www.tapvictoria.com

[4] A. Cento, The Airline Industry: Challenges in the 21st Century, Physica-Verlag, 2008.

[5] Air Transport Association, "2010 Economic Report," Air Transport Association, 2010.

[6] B. Alukos, "Fuel Prices - The Airline Industry's Toughest Headwind," Industry Reports, 09

April 2011. [Online]. Available: http://news.morningstar.com

[7] Centre for Asia Pacific Aviation, "US airlines look to international markets for future

growth," Aviation Market Intelligence, 18 August 2011. [Online].

Available: http://www.centreforaviation.com

[8] S. K. Ojha, Flight Performance of Aircraft, Wright-Patterson Air Force Base, Ohio:

American Institute of Aeronautics and Astronautics, 1995.

[9] W. Blake, Jet Transport Performance Methods, Boeing, 2009.

[10] FAA, Instrument Procedures Handbook, Skyhorse Publishing, 2008.

[11] Airbus, A340 Flight Deck and Systems Briefing for Pilots, Airbus, 2000.

[12] C. Anhalt, E. Breitbach and D. Sachau, "A Concept of a Shapevariable Fowler Flap on

Transport Aircraft," German Aearospace Center (DLR), Braunschweig, Germany, 2000.

[13] Airbus, A330 Flight Deck and Systems Briefing for Pilots, Airbus, 1999.

[14] Airbus, A320 Flight Deck and Systems Briefing for Pilots, Airbus, 1998.

[15] Airbus, Getting to Grips With Aircraft Performance, Airbus Customer Services, 2002.

[16] FAA, "Volume 4: Aircraft Equipment and Operational Authorizations," in FSIMS, FAA,

2007.

[17] Airbus, "Flight Operations Briefing Notes," Airbus, 2004.

[18] A. Aguiar and C. Figueiredo, Aeroplane Performance, TAP, 2011.

[19] TAP, A320 Flight Crew Operating Manual - Part 2: Flight Preparation, TAP, 2006.

60

[20] TAP, A320 Flight Crew Operating Manual - Part 3: Flight Operations, TAP, 2006.

[21] Airbus, "Limitations - Power Plant," in A330-A340 FCOM, Airbus.

[22] TAP, A330-A340 Flight Crew Operating Manual - General Information, TAP, 2011.

[23] V. d. Brederode, Fundamentos de Aaerodinâmica Incompressível, Instituto Superior

Técnico, 1997.

[24] M. Fueri, "Flex Temperature, Choice of Configuration," in 14th Performance & Operations

Conference, Bangkok, 2005.

[25] A. Aguiar, Aeroplane Performance, TAP, 2005.

[26] Airbus, Performance Programs Manual, Airbus, 2000.

[27] TAP, "A319–112 Airport Analysis," TAP, 2010.

[28] TAP, A330-A340 Flight Crew Operating Manual - Performance, TAP, 2011.

[29] E. Lesage, "LPC Landing," in 12th Performance and Operations Conference, Rome, 2003.

[30] D. Crocker, Dictionary of Aviation, London: A&C Black Publishers, 2007.

[31] M. F. S. Fitzsimmons, "The Electronic Flight Bag," United States Air Force Academy,

Colorado, 2002.

[32] J. Cahill and N. M. Donald, "Human Computer Interaction Methods for Electronic Flight

Bag," Cogn Tech Work, 2006.

[33] D. Michael, "Less Paper in the Cockpit," in 10th Performance and Operations Conference,

San Francisco, 1998.

[34] FAA, "Joint Aircraft System / Component Code," FAA, Oklahoma, 2008.

61

APPENDIX A – Regulation

Transcripts

A1. JAR 25 Subpart B Transcripts

This section contains transcripts from Joint Aviation Requirements, issued by the Joint Aviation

Authorities. The full document can be purchased from Global Engineering Documents, whose

worldwide offices are listed on the JAA website (www.jaato.com) and Global website

(www.global.ihs.com).

JAR 25.25 (Weight Limits)

“(a) Maximum weights. Maximum weights corresponding to the aeroplane operating conditions (such as ramp, ground taxi, take-off, en-route and landing) environmental conditions (such as altitude and temperature), and loading conditions (such as zero fuel weight, centre of gravity position and weight distribution) must be established so that they are not more than -

• The highest weight selected by the applicant for the particular conditions; or • The highest weight at which compliance with each applicable structural loading and

flight requirement is shown. (b) Minimum weight. The minimum weight (the lowest weight at which compliance with each applicable requirement of this JAR-25 is shown) must be established so that it is not less than -

• The lowest weight selected by the applicant; • The design minimum weight (the lowest weight at which compliance with each

structural loading condition of this JAR-25 is shown); or • The lowest weight at which compliance with each applicable flight requirement is

shown.”

JAR 25.103 (Stall Speed)

(a) The reference stall speed, VSR, is a calibrated airspeed defined by the applicant. VSR may not be less than a 1-g stall speed. VSR is expressed as:

√

where: VCLMAX = Calibrated airspeed obtained when the load factor-corrected lift coefficient

(

) is the first maximum during the maneuver prescribed in paragraph (c) of

this section. In addition, when the maneuver is limited by a device that abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher), VCLMAX may not be less than the speed existing at the instant the device operates;

nZW = Load factor normal to the flight path at VCLMAX; W = Aeroplane gross weight; S = Aerodynamic reference wing area; and

62

Q = Dynamic pressure.

(c) Starting from the stabilized trim condition, apply the longitudinal control to decelerate the

airplane so that the speed reduction does not exceed one knot per second.

JAR 25.107 (Takeoff Speeds)

“(a) V1 must be established in relation to VEF as follows: • VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must

be selected by the applicant, but may not be less than VMCG determined under JAR 25.149 (e).

• V1 in terms of calibrated airspeed, is the take-off decision speed selected by the applicant; however, V1 may not be less than VEF plus the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognises and reacts to the engine failure, as indicated by the pilot's application of the first retarding means during accelerate-stop tests.”

“(b) V2min, in terms of calibrated airspeed, may not be less than:

VSR for turbo-jet powered aeroplanes […]

1.10 times VMCA (c) V2, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by JAR 25.121(b) but may not be less than:

V2min; and

VR plus the speed increment attained before reaching a height of 35 ft above the take-off surface.”

“(d) VMU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and continue the takeoff. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground takeoff tests.” “(e) VR, in terms of calibrated air speed, must be selected in accordance with the conditions of paragraphs (e) (1) through (4) of this section:

VR may not be less than: - V1, - 105% of VMCA - The speed that allows reaching V2 before reaching a height of 35 ft above the

take-off surface, or - A speed that, if the aeroplane is rotated at its maximum practicable rate, will

result in a VLOF of not less than 1 10% of VMU in the all-engines-operating condition and not less than 105% of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition, except that in the particular case that lift-off is limited by the geometry of the aeroplane, or by elevator power, the above margins may be reduced to 108% in the all-engines-operating case and 104% in the one-engine-inoperative condition. (See ACJ 25. I07(e)( i)(iv).

(…)”

63

(f) VLOF is the calibrated airspeed at which the aeroplane first becomes airborne.”

JAR 25.113 (Take-off distance and take-off run)

(a) Take-off distance on a dry runway is the greater of:

The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, determined under JAR 25.111 for a dry runway;or

115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, as determined by a procedure consistent with JAR 25.1 11. (See ACJ 25.1 13(a)(2).)

(b) Take-off distance on a wet runway is the greater of:

The take-off distance on a dry runway determined in accordance with sub-paragraph (a) of this paragraph; or

The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2, before reaching 35 ft above the take-off surface, determined under JAR 25.111 for a wet runway. (See ACJ 113(a)(2).)

(c) If the take-off distance does not include a clearway, the take-off run is equal to the take-off distance. If the take-off distance includes a clearway:

The take-off run on a dry runway is the greater of: - The horizontal distance along the take-off path from the start of the take-off

to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, as determined under JAR 25.1 1 1 for a dry runway; or

- 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, determined by a procedure consistent with JAR 25.111. (See ACJ 25.1 13(a)(2).)

The take-off run on a wet runway is the greater of: - The horizontal distance along the take-off path from the start of the take-off

to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 ft above the take-off surface, determined under JAR 25.1 11 for a wet runway; or

- 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, determined by a procedure consistent with JAR 25.111. (See ACJ 25.113(a)(2).)

JAR 25.149 (Minimum control speed)

“(b) VMC[A] is the calibrated airspeed, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5 degrees.

64

(c)VMC[A] may not exceed 1.2 VS with: Maximum available take-off power or thrust on the engines;

• The most unfavourable centre of gravity; • The aeroplane trimmed for take-off; • The maximum sea-level take-off weight”

JAR 25.149 (Minimum Control Speed)

“(e) VMCG, the minimum control speed on the ground, is the calibrated airspeed during the take-off run, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with the use of the primary aerodynamic controls alone (without the use of nose-wheel steering) to enable the take-off to be safely continued using normal piloting skill. In the determination of VMCG, assuming that the path of the aeroplane accelerating with all engines operating is along the centreline of the runway, its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centreline is completed, may not deviate more than 30 ft laterally from the centreline at any point.”

JAR 25.149 (Minimum Control Speed)

“(f) VMCL, the minimum control speed during approach and landing with all engines operating, is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5º. VMCL must be established with:

• The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with all engines operating;

• The most unfavourable centre of gravity; • The aeroplane trimmed for approach with all engines operating; • The most unfavourable weight, or, at the option of the applicant, as a function of

weight. • Go-around thrust setting on the operating engines

(g) For aeroplanes with three or more engines, VMCL-2, the minimum control speed during approach and landing with one critical engine inoperative, is the calibrated airspeed at which, when a second critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with both engines still inoperative, and maintain straight flight with an angle of bank of not more than 5 degrees. VMCL-2 must be established with [the same conditions as VMCL, except that]:

• The aeroplane trimmed for approach with one critical engine inoperative • The thrust on the operating engine(s) necessary to maintain an approach • path angle of 3 degrees when one critical engine is inoperative • The thrust on the operating engine(s) rapidly changed, immediately after • the second critical engine is made inoperative, from the [previous] thrust to:

- the minimum thrust [and then to] - the go-around thrust setting

(h) In demonstrations of VMCL and VMCL-2, … lateral control must be sufficient to roll the aeroplane from an initial condition of steady straight flight, through an angle of 20 degrees in the direction necessary to initiate a turn away from the inoperative engine(s) in not more than 5 seconds.”

65

A2. AMJ 25-13 Transcripts

AMJ 25-13

"(4)(c) Reduced takeoff thrust, for an aeroplane, is a takeoff thrust less than the takeoff (or

derated takeoff) thrust. The aeroplane takeoff performance and thrust setting are established by

approved simple methods, such as adjustments, or by corrections to the takeoff thrust setting

and performance.”

“(5)(a) The reduced takeoff thrust setting

Is based on an approved takeoff thrust rating for which complete aeroplane

performance data is provided

Enables compliance with the aeroplane controllability requirements in the event that

takeoff thrust is applied at any point in the takeoff path

Is at least 75% of the maximum takeoff thrust for the existing ambient conditions”

“(f) The AFM states that [reduced thrust takeoffs] are not authorised on contaminated runways

and are not authorised on wet runways unless suitable performance accountability is made for

the increased stopping distance on the wet surface.”

66

APPENDIX B – Performance on Wet

and Contaminated Runways

This appendix on performance on wet and contaminated runways has the purpose of providing

a better understanding on the physical processes that take place on non-dry runways.

Different runway conditions will have different effects on the acceleration and deceleration

characteristics of an airplane. Wet and slippery runways will affect the aircraft’s deceleration

capability without affecting its acceleration. Standing water, slush and loose “compactible” snow

will affect an airplane’s acceleration capability as well as its deceleration. For that reason,

runway contaminants are divided into two different categories: solid contaminants and loose

contaminants [9].

Solid contaminants affect deceleration but have no effect on acceleration. This category

includes ice and compact snow.

Loose contaminants add a component of drag, retarding the aircraft’s motion and thus

affect both acceleration and deceleration. This includes loose snow and slush or

standing water with more than 0.125 inches deep

.

7.2 Solid Contaminants

Solid contaminants have a direct impact on aircraft braking coefficient. In general a wet runway

has less friction available for stopping an aircraft in an emergency. How much the runway

friction is reduced by moisture on the surface of the runway is a function of the material and

techniques of runway construction [9].

JAR 25.109, paragraph (c) provides equations for the wet runway “maximum braking coefficient

(tire-to-ground)” as a function of tire pressure and airplane ground speed:

Tire Pressure (psi) ( ) Maximum Braking Coefficient (tire-to-ground)

50 (

)

(

)

(

)

100 (

)

(

)

(

)

200 (

)

(

)

(

)

300 (

)

(

)

(

)

Where V is the true ground speed in knots; note that linear interpolation is allowed for tire

pressures other than the listed above.

As an example, for a tire pressure of 200 psi the maximum friction coefficient defined by the

equation will be as shown in Figure 58.

67

Figure 58 - Aircraft braking coefficient for a 200 psi tire pressure on a wet runway [9].

For its determination of the aircraft maximum braking coefficient on wet runways aircraft

manufacturers use a tire pressure which is approximately at the top of the range of tire

pressures for a given aircraft [9].

The maximum tire-to-ground wet runway braking coefficient of friction ( ) must be

adjusted to take into account the efficiency of the anti-skid system on a wet runway. Anti-skid

system operation must be demonstrated by flight testing on a smooth wet runway, and its

efficiency must be determined [9].

Based on the equations and the results of flight testing, then, aircraft manufacturers are able to

find a definition of the wet runway airplane braking coefficient for each aircraft, as shown in

Figure 59.

Figure 59 - Aircraft braking coefficient on a wet runway [9].

Because aircraft braking coefficient is a function of ground speed, the calculation of the stopping

distance on wet runways does not use a single constant value of as for dry runways.

Instead, the step integration of stopping distance will use a changing value of as the speed

decreases [9].

For solid contaminants other than wet or wet skid-resistant there is no universally accepted

relationship between runway description, reported braking action, and airplane performance.

The airplane’s actual performance may well be different for the same description of the runway

68

surface or the pilot-reported braking action. Aircraft manufacturers have been choosing, based

on experience, a relationship of reported braking action to airplane braking coefficient. This

relationship has been used to create the published data [9].

7.3 Loose Contaminants

The physics of takeoff on a runway having loose contaminants (see Figure 60) are similar to

those on a dry runway, with one notable exception: the addition of the drag on the airplane

resulting from the material which is covering the runway, be it standing water, slush, or wet

snow [9].

Figure 60 - Physics of contaminant drag [9].

Contaminant drag actually has two elements: displacement drag and impingement drag.

As illustrated in Figure 61, displacement drag results from the energy required for the landing

gear tires to displace the contaminant – that is, to move it out of their way as the airplane rolls

along the runway [9].

Impingement drag results from the airplane kinetic energy lost due to the impact of contaminant

on parts of the body (see Figure 62). The passage of the wheels through the contaminant

causes a very powerful spray to be thrown up; due to its density and the velocity at which it

strikes the airplane, it creates considerable impact force on the airplane. Since this impact force

is in an aftward direction, it subtracts from the airplane’s kinetic energy [9].

Figure 61 – Displacement Drag [9].

Figure 62 - Impingment Drag [9].

The contaminant impact can actually cause physical damage to an aircraft. As a result of this,

and because of the increasingly adverse effect of loose contaminants on takeoff performance

as depth increases, the FAA and JAA both state specifically that takeoff is prohibited on

runways having more than ½ inch (FAA) or 12.7 millimeters (JAA) of loose contaminant. The

latest EASA regulations on non-dry runways, however, permit up to 15 millimeters instead of the

earlier 12.7 mm (or ½ inch) [9].

69

Additionally, hydroplaning, or aquaplaning, is a dynamic condition encountered by an aircraft’s

tires when operating on runways covered with loose contaminant. At low speeds on a runway

having loose contaminant there is adequate time for the contaminant to move away from an

aircraft’s tires as it accelerates down the runway for takeoff, allowing the tires to remain in solid

contact with the runway surface. The presence of the contaminant does result in an increase of

the airplane’s drag, as discussed above, but there are no other adverse effects. However, as an

aircraft accelerates in loose contaminant, the tires cause an increase of pressure in the

contaminant in the area immediately ahead of them. When that pressure becomes sufficiently

great, it forces a wedge of fluid underneath the tires’ leading edges, thus lifting the tires out of

contact with the runway surface resulting in a loss of traction [9]:

Figure 63 – Hydroplaning effect [9].

The speed at which hydroplaning commences during an acceleration is known as the

hydroplaning speed VHP. It’s a function of tire pressure.

The EASA’s accepted equation for the hydroplaning speed is:

The following figure illustrates the repercussions that the different contaminants have on the

takeoff distance, for the same weight (292.97 tons) and V1 (160.6 kt), on a dry runway with

3352.8 meters long (11,000 ft):

Figure 64 - Effect of contaminants on takeoff distances [9].

70

APPENDIX C – TLP

C1. Files

a) OCTOPUS Input

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*FLIGHT MANUAL VERSION : 9

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*CDL DATA FILE ISSUE : 5

------------------------------

UNITS

------------------------------

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*FORCES UNIT (1=DAN 2=LB) : 1

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------------------------------

AIRCRAFT DATA

------------------------------

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WEIGHT INITIAL POINT : 35000.000

MAXIMUN STRUCTURAL WEIGHT : 100000.000

MAXIMUN STRUCTURAL WEIGHT FOR LANDING : 999000.000

*CONFIGURATION (CF SUM GLO : 3

CONFIGURATION INITIAL POINT (CF SUM GLO : 1

CG FORWARD POSITION : 0.000

*CG FORWARD LIMIT CODE (1=BASIC 2=ALTERN : 1

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FLIGHT CG INITIAL POINT : 25.000

LANDING GEAR POSITION INITIAL POINT : 1

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71

------------------------------

ATMOSPHERE DATA

------------------------------

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RELATIVE HUMIDITY : 80.000

PRESSURE : 1013.250

CURRENT PRESSURE ALTITUDE (NOT USED) : 1.000

TEMPERATURE TYPE (1=OAT 2=DISA) : 1

TEMPERATURE : 14.000

*WIND IN X AXIS : 0.000

*WIND IN Y AXIS : 0.000

WIND : 0.000

------------------------------

ENGINE DATA

------------------------------

*AIR COND (1=OFF 2=ON 3=ECO 4=MAX) : 1

*ANTI-ICING (1=OFF 2=ENG 3=ENG+AIRF) : 1

AIR COND INITIAL POINT (CF AIR COND) : 1

ANTI-ICING INITIAL POINT (CF ANTI-ICING : 1

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*ENGINE OPTION : 1

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NUMBER OF INOPERATIVE ENGINES : 1

K FN DETERIORATION : 100.000

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FIXED PMP VALUE : 0.000

*REVERSE CREDIT (1=ALL REV INOP., 2=ALL : 1

FIXED THRUST VALUE : 0.000

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DISPATCH IN N1 MODE : 1

------------------------------

GEARS DATA

------------------------------

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*AUTOBRAKES (1=OFF) : 1

*BRAKING FAILED (1=0 BRAKE INOPERATIVE 2 : 1

BRAKING FAILED CENTRAL GEAR (1=0 BRAKE : 1

BRAKING FAILED WING GEAR (1=0 BRAKE INO : 1

BRAKING FAILED BODY GEAR (1=0 BRAKE INO : 1

BRAKE MODE (CF SUM GLOSSARY) : 1

CENTRAL GEARS RETRACTED (1=NO 2=YES) : 1

*LANDING GEAR EXTENDED (1=NO 2=YES) : 1

LANDING GEARS POSITION (1=UP 2=DOWN) : 1

*HYDRAULIC PUMP FAILURE (1=NO 2=YES) : 1

*TACHOMETER FAILURE (1=NO 2=YES) : 1

------------------------------

REGULATION DATA

------------------------------

*LOWEST LIM. GROSS LEV.-OFF HEIGHT TYPE : 2

*LOWEST LIM. GROSS LEV.-OFF HEIGHT : 1500.000

*OBSTACLE CLEARANCE (1=NORM 2=15 FT 3=35 : 1

*SCREEN HEIGHT AT END OF RUNWAY : 1

------------------------------

RUNWAY DATA

------------------------------

NUMBER OF RUNWAYS : 1

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ALIGMENT 0 DEGREE (TODA,TORA) : 0.000

ALIGMENT 0 DEGREE (ASDA) : 0.000

ALIGMENT 90 DEGREE (TODA,TORA) : 0.000

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ALIGMENT 180 DEGREE (TODA,TORA) : 0.000

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ALIGMENT 180PAD (ASDA) : 0.000

ALIGMENT 180 OTHER (TODA,TORA) : 0.000

ALIGMENT 180 OTHER (ASDA) : 0.000

CURRENT RUNWAY NUMBER : 1

72

*AIRPORT IDENTIFICATION : LISBOA

*RUNWAY IDENTIFICATION : 17

*ICAO CODE : LPPT

*IATA CODE : LIS

RUNWAY QFU : 17

*RUNWAY SLOPE : -0.540

HEADING : 173.000

*RUNWAY ALTITUDE TYPE (1=ZP 2=QNH 3=QFE) : 2

*RUNWAY PRESSURE ALTITUDE : 1013.250

*RUNWAY GEOMETRIC ALTITUDE : 374.000

*RUNWAY LENGTH REPRESENTATION (1=TODA-AS : 1

*ASDA OR STOPWAY : 2304.000

*MULTIPLICATION FACTOR ON ASDA : 1.000

*INCREMENT VALUE ON ASDA : 0.000

*ALIGNMENT ALLOWANCE FOR ASDA : 28.900

*TODA OR CLEARWAY : 2304.000

*AVAILABLE RUNWAY DIST.(TORA) : 2304.000

*ALIGNMENT ALLOWANCE FOR TORA AND TODA : 12.000

ENTRY ANGLE : 2

ENTRY ANGLE (UNUSED) : 1

LDA : 0.000

ADDITIVE COEFFICIENT ON LDA : 0.000

MULTIPLICATIVE OEFFICIENT ON LDA : 1.000

*RUNWAY STATE (1=DRY 2=WET 3=WATER_1/4" : 1

RUNWAY SURFACE (1=SMOOTH 2=GROOVED/PFC) : 1

STOPWAY SURFACE (1=SMOOTH 2=GROOVED/PFC : 1

RUNWAY TEMPERATURE : 0.000

REFERENCE FOR OBSTACLE DEFINITION : 2

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2420.000 0.000 0.000 0.000 0.000 0.000 (…)

(…)

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(…)

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FINAL FLIGHT PATH HALFWIDTH : 900.000

*RUNWAY WIDTH : 45.000

RUNWAY + STAB. SHOULDER WIDTH LT 58M : 1

*COMMENT LINE 1 FOR TAKE-OFF :

*COMMENT LINE 2 FOR TAKE-OFF :

COMMENT LINE 1 FOR LANDING :

COMMENT LINE 2 FOR LANDING :

APPROACH GRADIENT (RUNWAY) : 0.000

DELTA ALTITUDE FOR ACG CALCULATION : 0.000

ILS GLIDE (RUNWAY) : 0.000

------------------------------

SPOILERS DATA

------------------------------

*SPOILERS (1=ALL SP OPER 2=ALL SP INOP 3 : 1

AILERON ANTI DROOP FUNCTION (1=NO 2=YE : 1

------------------------------

TURNS DATA

------------------------------

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NUMBER OF TURN : 0

*TURN TYPE

2

*TURN VALUE

15.000

*START TURN POINT TYPE

2

*START TURN POINT VALUE

1500.000

*END TURN POINT TYPE

5

*END TURN POINT VALUE

73

180.000

------------------------------

SPEED DATA

------------------------------

SPEED VALUE (or V/VS) : 46.300

V1 TYPE (1=V1/VR 2=CAS 3=IAS) : 1

V1 (or V1/VR) VALUE : 1.000

V2 TYPE (1=V2/VS 2=CAS 3=IAS) : 1

V2 (OR V2/VS) VALUE : 1.130

VC VALUE : 0.000

SPEED TYPE (1=V/VS 2=CAS 3=IAS) : 1

V/VS VALUE : 1.230

V1 LIMITATION CODE (1=MIN 2=MAX 3=BALAN : 1

------------------------------

PERFORMANCE DATA

------------------------------

MODELISATION (1=AFM 2=POLYNOMIALE 3=NEU : 0

CATEGORY II APPROACH (1=NO 2=YES) : 1

DELTA V (CAS) : 0.000

2ND SEGMENT GRADIENT VALUE : 0.000

GRADIENT VALUE : 0.500

SPEED (OR K) VALUE : 1.230

LANDING CONFIGURATION : 1

GRADIENT CALCULATION WITH REGULATORY VA : 2

WEIGHT OR GRADIENT CALCULATION : 1

*EXTENDED SECOND SEGMENT : 2

REGULATORY COEFFICIENT : 1.150

SSG OR WEIGHT CALCULATION : 1

ETOPS LAW : 1

CAS FOR USER'S ETOPS LAW : 0.000

MACH FOR USER'S ETOPS LAW : 0.000

LANDING IN CLEAN CONFIGURATION : 1

USER' DECELERATION : 2.000

NET CEILING CALCULATION (1=NO 2=YES) : 1

DRIFT-DOWN CALCULATION (1=NO 2=YES) : 1

AUTOLAND CALCULATION (1=NO 2=YES) : 1

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TEMPERATURE OPTION FOR AUTOLAND : 1

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PRESSURE ALTITUDE FOR AUTOLAND : 0.000

VMBE CALCULATION (1=NO 2=YES) : 1

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DISTANCE VALUE FOR WEIGHT CALCULATION : 3000.000

FTO CHECK (1=YES 2=NO) : 1

------------------------------

ADDITIVE VMC DATA

------------------------------

VMC TYPE : 1

DISA TEMPERATURE : 0.000

------------------------------

ADDITIVE AIRSPEED CALIBRATION DATA

------------------------------

GROUND CONTACT : 1

CONTEXT (1=TAKEOFF 2=LANDING) : 1

------------------------------

TAKE OFF OPTIMIZATION DATA

------------------------------

*OPTIMIZATION TYPE (1=POLYNOMIAL 2=FIRST : 2

OPTIMIZATION METHOD (1=DEGREE 2 2=SIMPL : 0

MODELISATION (1=POLYNOMIALE 2=NEURAL) : 0

*OUTPUT LEVEL (1=VERY SHORT 2=SHORT 3=FU : 2

*V1/VR CALCULATION MODE (1=FULL RANGE 2= : 1

*V2/VS CALCULATION MODE (1=FULL RANGE 2= : 1

V1/VR MIN : 0.840

V1/VR MAX : 1.000

V2/VS MIN : 1.130

V2/VS MAX : 1.400

DRY/WET COMPARAISON : 2

*ACG CHECK : 1

*AQUAPLANING EFFECT ON DRAG (1=NORMAL 2= : 1

*CHECK VS 1/4" (6.3MM) CONT DEPTH (1=NO : 1

74

*TFLEX MAX DISA : 43.000

------------------------------

CONSTRAINT DEGRADATIONS DATA

------------------------------

*COEF. TOD1 : 1.000

*ADD. TOD1 : 0.000

*COEF. TOR1 : 1.000

*ADD. TOR1 : 0.000

*COEF. TOD0 : 1.000

*ADD. TOD0 : 0.000

*COEF. TOR0 : 1.000

*ADD. TOR0 : 0.000

*COEF. ASD1 : 1.000

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*ADD. ASD0 : 0.000

*COEF. FSG : 1.000

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*COEF. SSG : 1.000

*ADD. SSG : 0.000

*COEF. FTO : 1.000

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*COEF. VMCG : 1.000

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*COEF. VMCA : 1.000

*ADD. VMCA : 0.000

*COEF. VMU : 1.000

*ADD. VMU : 0.000

*COEF. ENERGY RATIO : 1.000

*ADD. ENERGY RATIO : 0.000

COEF. ACG : 1.000

ADD. ACG : 0.000

COEF. LCG : 1.000

ADD. LCG : 0.000

COEF. LD : 1.000

ADD. LD : 0.000

COEF. VMCL : 1.000

ADD. VMCL : 0.000

*COEF. VTYRE : 1.000

*ADD. VTYRE : 0.000

------------------------------

CALCULATION MODE

------------------------------

*ABSCISSA : 6

*ABSCISSA VALUES : 34

5.000 10.000 15.000 20.000 25.000 30.000 (…)

(…)

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ISO : 4

ISO VALUES : 0

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b) OCTOPUS Output

CALCULATION FILE NAME :

---------------------

INPUT

OCTOPUS VERSION : 27.0.1

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AC211B05 A321-211 /V 9

-------------

------------------------------

I INPUT DATA RECAPITULATION I

75

------------------------------

Take-off optimization type : FIRST PRINCIPLE METHOD

Level of output : SHORT

V1/VR calculation mode : FULL RANGE

V2/VS calculation mode : FULL RANGE

Extended second segment : NO

Screen height at end of runway : NORMAL

Obstacle clearance : NORMAL

Low. lim. gross level-off height option : VALUE

Lowest limitation gross level-off height: 1500.000 FT

Aquaplaning effect on drag : NORMAL

Check vs 1/4" (6.3mm) cont depth : NO

Wind(runway) : 0.000 KT

Crosswind : 0.000 KT

Altitude type : QNH

Pressure altitude : 1013.250 HPA

Maximum structural weight : 100000.000 KG

Configuration : CONF 1+F

Engine option : TOGA

Air conditioning : Off

Anti-icing : Off

CG code : Basic

Turn option : NO

ACG Check : NO

Tflex Max DISA : 43.000 DEG C

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Reversers credit : ALL REVERSERS INOPERATIVE

Antiskid : ON

Flight with landing gears extended : NO

Braking failed : 0 BRAKE INOPERATIVE

Autobrake : OFF

Spoilers : ALL SPOILERS OPERATING

Ground idle failed : NO

Eng A-Ice valve blocked open : NO

Hydraulic pump failure : NO

Tachometer failure : NO

CURRENT RUNWAY NUMBER : 1

Airport identification : LISBOA

Runway identification : 17

Airport ICAO code : LPPT

Airport IATA code : LIS

Airport elevation : 374.000 FT

Runway length representation : TODA - ASDA

TORA : 2304.000 M

TODA or clearway : 2304.000 M

ASDA or stopway : 2304.000 M

Alignment allowance selection : STANDARD

Alignment allowance for TORA and TODA : 12.000 M

Alignment allowance for ASDA : 28.900 M

Multiplicatif coefficient on ASDA : 1.000

Additif coefficient on ASDA : 0.000 M

Runway slope : -0.540 %

Runway width : 45.000 M

Runway condition : DRY

Number of obstacles to take account : 1.000

Comment line 1 for take-off :

Comment line 2 for take-off :

Obstacle reference END OF TORA

Obstacle X position M

2420.000

Obstacle Y position M

0.000

Obstacle H position FT

145.000

DEGRADATION ON CONSTRAINTS :

NO COEFFICIENT ON A/C PERFORMANCE

Number of negligible CDL items : 0.000

CALCULATION NAME : TAKE-OFF OPTIMIZATION

76

----------------

ABSCISSA CALCULATION

--------------------

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI MAX WEIGHT I 1ST SEG W I 2ND SEG W I LIM COD1 V1MII

I--------------I--------------I--------------I--------------I--------------I

I DEG C I KG I KG I KG I I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 88626.2 I 103935.7 I 96109.9 I 6. I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 87902.5 I 103809.8 I 96013.9 I 6. I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 69538.2 I 76386.1 I 71267.2 I 19. I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI LIM COD2 V1MII LIM COD1 V1MAI LIM COD2 V1MAI LIM COD1 V1BAI

I--------------I--------------I--------------I--------------I--------------I

I DEG C I I I I I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 3. I 6. I 3. I 0. I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 3. I 6. I 3. I 0. I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 6. I 19. I 6. I 0. I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI LIM COD2 V1BAI V2/VS I V1/VR MIN I V1/VR MAX I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I I I I I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 0. I 1.140 I 0.908 I 0.908 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 0. I 1.140 I 0.907 I 0.907 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 0. I 1.143 I 0.981 I 0.981 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI V1/VR BAL I V1 MIN IAS I V1 MAX IAS I V1 BAL IAS I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I I KT I KT I KT I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 0.000 I 140.055 I 140.055 I 0.000 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 0.000 I 139.304 I 139.304 I 0.000 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 0.000 I 135.750 I 135.750 I 0.000 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

77

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI V2 IAS I VR IAS I TOD1 V1 BAL I TOD1 V1 MIN I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I KT I KT I M I M I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 159.699 I 154.145 I 0.0 I 2290.6 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 159.045 I 153.474 I 0.0 I 2290.9 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 142.260 I 138.332 I 0.0 I 2097.2 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI TOD1 V1 MAX I TOR1 V1 BAL I TOR1 V1 MIN I TOR1 V1 MAX I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I M I M I M I M I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 2290.6 I 0.0 I 2092.2 I 2092.2 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 2290.9 I 0.0 I 2094.7 I 2094.7 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 2097.2 I 0.0 I 1870.6 I 1870.6 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI ASD V1 BAL I ASD V1 MIN I ASD V1 MAX I 1.15 TOD0 I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I M I M I M I M I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 0.0 I 2273.6 I 2273.6 I 1956.7 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 0.0 I 2274.0 I 2274.0 I 1959.9 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 0.0 I 2273.6 I 2273.6 I 1991.7 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI 1.15 TOR0 I GROSS 1ST SEGI GROSS 2ND SEGI GROSS FTO I

I--------------I--------------I--------------I--------------I--------------I

I DEG C I M I % I % I % I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 1811.6 I 1.953 I 3.466 I 7.085 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 1814.2 I 2.044 I 3.563 I 7.195 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 1849.6 I 1.142 I 2.714 I 3.312 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI BR ENER V1 MII BR ENER V1 MAI BR ENER V1 BAI OH2MIN I

I--------------I--------------I--------------I--------------I--------------I

78

I DEG C I % I % I % I FT I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 75.3 I 75.3 I 0.0 I 1098.1 I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 75.4 I 75.4 I 0.0 I 1128.3 I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 65.1 I 65.1 I 0.0 I 1183.5 I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I OAT TEMPERATUI OH2MAX I NUM OBST V1MII NUM OBST V1MAI NUM OBST V1BAI

I--------------I--------------I--------------I--------------I--------------I

I DEG C I FT I I I I

I--------------I--------------I--------------I--------------I--------------I

I 5.000 I 2314.2 I 0. I 0. I 0. I

I--------------I--------------I--------------I--------------I--------------I

I 10.000 I 2436.0 I 0. I 0. I 0. I

I--------------I--------------I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I--------------I--------------I

I 57.000 I 1691.4 I 1. I 1. I 0. I

I--------------I--------------I--------------I--------------I--------------I

I 58.000 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I

I OAT TEMPERATUI OH2GMINP I OH2GMAXP I

I--------------I--------------I--------------I

I DEG C I FT I FT I

I--------------I--------------I--------------I

I 5.000 I 1500.0 I 3270.3 I

I--------------I--------------I--------------I

I 10.000 I 1500.0 I 3348.2 I

I--------------I--------------I--------------I

(…)

I--------------I--------------I--------------I

I 57.000 I 1500.0 I 2171.6 I

I--------------I--------------I--------------I

I 58.000 I************* I************* I

I--------------I--------------I--------------I

79

c) TLP – Takeoff Optimization Output

80

d) TLP – Landing Optimization Output

81

e) Sample Excel File produced during TLP validation

82

C2. Visual Basic Classes

a) Airport Class

83

b) Aircraft Class

84

C3. Functions

a) tISA

'Returns the standard temperature (°C) at a given altitude (ft)

Public Function tISA(ByVal altitude As Decimal)

Dim t_isa As Decimal

'Above MSL and below the tropopause (36,089 feet):

' (Page 70 - Jet Transport Performance Methods, The Boeing Company)

Dim T0 As Decimal = 15 '[°C] (standard temperature at sea level)

t_isa = T0 - 0.0019812 * altitude

Return t_isa

End Function

b) pa2p

'Returns the pressure value (P in hPA) corresponding to the specified pressure

'altitude (PA in ft)

Public Function pa2p(ByVal pa As Decimal)

Dim P As Decimal

If pa >= 0 Then

' Above MSL and below the tropopause (36,089 feet):

' (Page 18 - Gettin to Grips with AC Performance)

Dim P0 As Decimal = 1013.25 '[hPa] (standard pressure at MSL)

Dim T0 As Decimal = 288.15 '[K] (standard temperature MSL)

Dim α As Decimal = 0.0065 '[°C/m]

Dim g0 As Decimal = 9.80665 '[m/s2]

Dim R As Decimal = 287.053 '[J/kg/K]

Dim h As Decimal '[m] (altitude)

' conversion from feet to meters

h = pa * 0.3048

P = P0 * (1 - α * h / T0) ^ (g0 / (α * R)) '[hPa]

Else

'Below MSL

Dim a As Decimal = -28

Dim b As Decimal = 28371

P = (pa - b) / a

End If

Return P

End Function

c) p2pa

'Returns the pressure altitude value (h in ft) corresponding to the specified

pressure (P in hPa)

Public Function p2pa(ByVal P As Decimal)

Dim h As Decimal '[m] (altitude)

If P >= 1013.25 Then

' Above MSL and below the tropopause (36,089 feet):

' Rearrangement of the formula from:

85

' Page 18 - Gettin to Grips with AC Performance

Dim P0 As Decimal = 1013.25 '[hPa] (standard pressure at MSL)

Dim T0 As Decimal = 288.15 '[K] (standard temperature at MSL)

Dim α As Decimal = 0.0065 '[ºC/m]

Dim g0 As Decimal = 9.80665 '[m/s2]

Dim R As Decimal = 287.053 '[J/kg/K]

Dim m2ft As Decimal = 3.28083 'conversion from meter to feet

h = (T0 / α) * (1 - (P / P0) ^ (α * R / g0)) '[m]

h = h * m2ft '[ft]

Else

' Below MSL

Dim a As Decimal = -28

Dim b As Decimal = 28371

h = a * P + b

End If

Return h

End Function

d) SetInitialTemperatureValues()

'Computes Tref, Tmax and Tflexmax

Public Sub SetInitialTemperatureValues( ByVal pressure As Decimal,

ByVal pressure_setting As String,

ByVal elevation As Decimal,

ByVal Aircraft As Plane,

ByRef tref As Decimal,

ByRef tmax As Decimal,

ByRef tflexmax As Decimal )

Dim tflexmax_ISA, tflexmax_dISA As Decimal

Dim altitude_correction, t_correction, pressure_altitude As Decimal

If pressure_setting = "QNH" Then

'QNH

altitude_correction = BLL.p2pa(pressure)

pressure_altitude = elevation + altitude_correction

Else

'ZP

pressure_altitude = pressure

End If

'Estimate temperature values

tref = pressure_altitude * Aircraft.tref_a + Aircraft.tref_b

tmax = pressure_altitude * Aircraft.tmax_a + Aircraft.tmax_b

tflexmax = pressure_altitude * Aircraft.tflexmax_a + Aircraft.tflexmax_b

'Estimate temperature correction

tflexmax_dISA = BLL.ParseString2Num(Aircraft.tflex_max_disa)

tflexmax_ISA = BLL.tISA(elevation) + tflexmax_dISA

t_correction = tflexmax_ISA – tflexmax

'Apply correction

tref += t_correction

tmax += t_correction

tflexmax = tflexmax_ISA

End Sub

86

APPENDIX D – FAJS-21R

87

88

89

90

APPENDIX E – FM Page - A330-202

91

APPENDIX F – Obstacles Limitation

Verification

The following graphics were obtained in Excel. The corresponding data points were calculated by the Flight Path function of PEP’s certified FM module. Position (0,0) corresponds to brake release.

92

93

94

95

APPENDIX G – PEP-FM Files

F1. Complete Takeoff Function

OCTOPUS VERSION : 27.0.0

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AB202C02 A330-202 /V13

-------------

------------------------------

I INPUT DATA RECAPITULATION I

------------------------------

Runway condition : DRY

Pressure altitude : 924.625 FT

Runway slope : 0.160 %

Temperature type : OAT

Temperature : 25.000 DEG C

Wind(runway) : 0.000 KT

Air conditioning : Off

Anti-icing : Off

Engine option : TOGA

Configuration : CONF 1+F

CG code : Basic

Weight : 238857.000 KG

V1 type : V1/VR

V1 : 0.936

V2 type : V2/VS

V2 : 1.218

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Reversers credit : ALL REVERSERS INOPERATIVE

Antiskid : ON

Braking failed : 0 BRAKE INOPERATIVE

Autobrake : OFF

Flight with landing gears extended : NO

Spoilers : ALL SPOILERS OPERATING

Ground idle failed : NO

Eng A-Ice valve blocked open : NO

Tachometer failure : NO

Number of negligible CDL items : 0.000

CALCULATION NAME : COMPLETE TAKE-OFF

----------------

APPROVED if edited or printed by AIRBUS PEP tool

30-AUG-11

POINT CALCULATION

-----------------

I--------------I--------------I--------------I--------------I--------------I

I TOD OEI I 1.15 TOD AEO I TOR OEI I 1.15 TOR AEO I ASD OEI I

I--------------I--------------I--------------I--------------I--------------I

I M I M I M I M I M I

I--------------I--------------I--------------I--------------I--------------I

I 3885.6 I 3266.4 I 3556.7 I 3078.5 I 3327.6 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I ASD AEO I BRK ENER AEO I BRK ENER OEI I V1 CAS I V1 IAS I

I--------------I--------------I--------------I--------------I--------------I

96

I M I % I % I KT I KT I

I--------------I--------------I--------------I--------------I--------------I

I 3414.1 I 99.7 I 93.8 I 155.620 I 153.595 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I VR CAS I VR IAS I VLOF0 CAS I VLOF0 IAS I VLOF1 CAS I

I--------------I--------------I--------------I--------------I--------------I

I KT I KT I KT I KT I KT I

I--------------I--------------I--------------I--------------I--------------I

I 166.260 I 163.810 I 177.535 I 176.035 I 170.488 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I VLOF1 IAS I V2 CAS I V2 IAS I V2/VS I 1ST SEG GRAD I

I--------------I--------------I--------------I--------------I--------------I

I KT I KT I KT I I % I

I--------------I--------------I--------------I--------------I--------------I

I 168.988 I 170.941 I 169.441 I 1.218 I 1.222 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I

I 2ND SEG GRAD I N1 I

I--------------I--------------I

I % I % I

I--------------I--------------I

I 2.939 I 109.8 I

I--------------I--------------I

CKSUM2 = -408649586

97

F2. Landing Distance Function Output

OCTOPUS VERSION : 27.0.0

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AB202C02 A330-202 /V13

-------------

------------------------------

I INPUT DATA RECAPITULATION I

------------------------------

Regulatory multiplication coefficient : 1.150

Runway condition : SLUSH 1/4"

Pressure altitude : 5558.000 FT

Wind(runway) : 10.000 KT

Configuration : CONF FULL

CG code : Basic

Weight : 186000.000 KG

Engine option : NO BUMP

k(V/VS) : 1.230

Delta V (CAS) : 0.000 KT

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Reversers credit *: ALL REVERSERS INOPERATIVE

Antiskid : ON

Braking failed : 0 BRAKE INOPERATIVE

Spoilers : ALL SPOILERS OPERATING

Ground idle failed : NO

Tachometer failure : NO

Number of negligible CDL items : 0.000

CALCULATION NAME : LANDING DISTANCE

----------------

APPROVED if edited or printed by AIRBUS PEP tool

29-AUG-11

POINT CALCULATION

-----------------

I--------------I--------------I--------------I--------------I--------------I

I LD I REGUL COEF I REQUIRED LD I FACTORED LD I VFA CAS I

I--------------I--------------I--------------I--------------I--------------I

I M I I M I M I KT I

I--------------I--------------I--------------I--------------I--------------I

I 2158.2 I 1.150 I 2482.0 I************* I 138.167 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I VFA IAS I BRK ENER AEO I VREF CAS I DELTA VREF I FAILURE LD I

I--------------I--------------I--------------I--------------I--------------I

I KT I % I KT I KT I M I

I--------------I--------------I--------------I--------------I--------------I

I 137.333 I 36.2 I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I

I FAILURE COEF I FAILURE BRK EI

I--------------I--------------I

I I % I

I--------------I--------------I

I************* I************* I

I--------------I--------------I

CKSUM2 = 1946801872

98

F3. Operational Landing Distance Function Output

OCTOPUS VERSION : 27.0.0

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AB202C02 A330-202 /V13

-------------

------------------------------

I INPUT DATA RECAPITULATION I

------------------------------

Runway condition : SLUSH 1/4"

Pressure altitude : 5558.000 FT

Wind(runway) : 10.000 KT

Configuration : CONF FULL

CG code : Basic

Brake mode : LOW

Weight : 186000.000 KG

Engine option : NO BUMP

k(V/VS) : 1.230

Delta V (CAS) : 0.000 KT

Autoland : NO

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Reversers credit *: ALL REVERSERS INOPERATIVE

Number of negligible CDL items : 0.000

CALCULATION NAME : OPERATIONAL LANDING DISTANCE

----------------

FOR INFORMATION ONLY

29-AUG-11

POINT CALCULATION

-----------------

I--------------I--------------I--------------I--------------I--------------I

I AIRBORNE DISTI GROUND DIST I ACTUAL LD I VFA CAS I VFA IAS I

I--------------I--------------I--------------I--------------I--------------I

I M I M I M I KT I KT I

I--------------I--------------I--------------I--------------I--------------I

I 522.1 I 1762.5 I 2284.6 I 138.167 I 137.333 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I--------------I--------------I

I BRK ENER AEO I VREF CAS I DELTA VREF I FAILURE LD I FAILURE COEF I

I--------------I--------------I--------------I--------------I--------------I

I % I KT I KT I M I I

I--------------I--------------I--------------I--------------I--------------I

I 31.8 I************* I************* I************* I************* I

I--------------I--------------I--------------I--------------I--------------I

I--------------I

I FAILURE BRK EI

I--------------I

I % I

I--------------I

I************* I

I--------------I

CKSUM2 = -1226750293

99

F4. Landing Climb Gradient Function Output

OCTOPUS VERSION : 27.0.0

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AB202C02 A330-202 /V13

-------------

------------------------------

I INPUT DATA RECAPITULATION I

------------------------------

Weight or gradient calculation : WEIGHT CALCULATION

Gradient calculation option : NORMAL

Gradient : 3.500 %

Temperature type : OAT

Temperature : 3.000 DEG C

Pressure altitude : 5558.000 FT

Air conditioning : Off

Anti-icing : Off

Configuration : CONF FULL

CG code : Basic

Engine option : NO BUMP

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Eng A-Ice valve blocked open : NO

Number of negligible CDL items : 0.000

CALCULATION NAME : LANDING CLIMB GRADIENT

----------------

APPROVED if edited or printed by AIRBUS PEP tool

29-AUG-11

POINT CALCULATION

-----------------

I--------------I--------------I--------------I--------------I--------------I

I WEIGHT I LCG I W REGUL LCG I REGUL LCG I SPEED (CAS) I

I--------------I--------------I--------------I--------------I--------------I

I KG I % I KG I % I KT I

I--------------I--------------I--------------I--------------I--------------I

I 267227.2 I 3.500 I************* I 3.200 I 165.884 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I

I SPEED (IAS) I REG SP (CAS) I REG SP (IAS) I

I--------------I--------------I--------------I

I KT I KT I KT I

I--------------I--------------I--------------I

I 165.218 I************* I************* I

I--------------I--------------I--------------I

CKSUM2 = 2042245409

100

F5. Approach Climb Gradient Function Output

OCTOPUS VERSION : 27.0.0

---------------

REGULATION NAME : JAA

---------------

AIRCRAFT NAME : AB202C02 A330-202 /V13

-------------

------------------------------

I INPUT DATA RECAPITULATION I

------------------------------

Gradient calculation option : NORMAL

Weight or gradient calculation : WEIGHT CALCULATION

Gradient : 3.500 %

Type of approach climb : CATEGORY 2 APPROACH

Temperature type : OAT

Temperature : 3.000 DEG C

Pressure altitude : 5558.000 FT

Air conditioning : Off

Anti-icing : Off

Configuration : CONF 3

CG code : Basic

Engine option : NO BUMP

- SPECIAL CASES ARE INDICATED WITH A STAR (*) -

Eng A-Ice valve blocked open : NO

Flight with landing gears extended : NO

Number of negligible CDL items : 0.000

CALCULATION NAME : APPROACH CLIMB GRADIENT

----------------

APPROVED if edited or printed by AIRBUS PEP tool

29-AUG-11

POINT CALCULATION

-----------------

I--------------I--------------I--------------I--------------I--------------I

I WEIGHT I ACG I W REGUL ACG I REGUL ACG I SPEED (CAS) I

I--------------I--------------I--------------I--------------I--------------I

I KG I % I KG I % I KT I

I--------------I--------------I--------------I--------------I--------------I

I 186028.0 I 3.500 I************* I 2.500 I 143.177 I

I--------------I--------------I--------------I--------------I--------------I

I--------------I--------------I--------------I

I SPEED (IAS) I REG SP (CAS) I REG SP (IAS) I

I--------------I--------------I--------------I

I KT I KT I KT I

I--------------I--------------I--------------I

I 142.677 I************* I************* I

I--------------I--------------I--------------I

CKSUM2 = -1867246782