RNAV System Requirements for airplanes

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RNAV in Europe - Procedure Design Master Class EUROCONTROL 1 RNAV System Requirements (1) FMS database issues FMS architecture FMS database production What RNAV can do FMS limitations Aircraft owner Aircraft manufacturer FMC manufacturer Database supplier

description

RNAV in Europe - Procedure Design Master ClassRNAV System Requirements (1)‡ FMS database issues‡ ‡ ‡ ‡ FMS architecture FMS database production What RNAV can do FMS limitationsEUROCONTROL‡ ‡ ‡ ‡Aircraft owner Aircraft manufacturer FMC manufacturer Database supplier1RNAV in Europe - Procedure Design Master ClassRNAV System Requirements (2)‡ Navigation Performance ‡ Accuracy, Integrity, Availability & Continuity ‡ Need for accurate data in WGS 84 ‡ Need for appropriate toolsEURO

Transcript of RNAV System Requirements for airplanes

Page 1: RNAV System Requirements for airplanes

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RNAV System Requirements (1)

• FMS database issues• FMS architecture• FMS database production • What RNAV can do• FMS limitations

• Aircraft owner• Aircraft manufacturer• FMC manufacturer• Database supplier

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RNAV System Requirements (2)

• Navigation Performance• Accuracy, Integrity, Availability &

Continuity• Need for accurate data in WGS 84• Need for appropriate tools

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RNAV System Requirements

FMS Architecture• System Architecture

• Main elements:• Flight Management Computer(s)

• Control Display Unit

• Navigation Display

• Navigation sensor (mix)

• Additional elements• Update sensors (DME/GPS/IRS)

• Navigation database

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RNAV System Requirements

FMS Database production• Every 4 weeks a new navigation database• Double cycle system: old and new version stored and

retrievable by the crew• Navigation data provided by the database supplier• Non tailored (AIP) and tailored (company routes) data

compiled• Engine and Airline Policy data added and navigation

data • Update closes 2 weeks before the effective date

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RNAV System Requirements

FMS Database production (2)

• Diskettes produced by the FMC manufacturer (Honeywell) or licensee (Racal/Jeppesen)

• changes checked by the navigation database diskette producer

• Shipment of navigation diskettes/data-transfer to the Aircraft Operator

• Data available ~1 week before the effective date• Loading via Nav Database loader before the effective

date

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RNAV System Requirements

FMS Database production (3)

• Nav Database capacity• 96 Kb/192Kb/500Kb/1Mb/........

• Nav Database structure• Sub-files:

• Airways• Navigation facilities (ILS/VOR/DME/NDB)• Way points• Airports• Runways• Gate positions• TMA procedures

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RNAV System Requirements

FMS Database production (4)

• Coding rules according AIRINC 424 specification

• Path and Terminator concept• Flight paths normally designed for non RNAV

aircraft• ~20 different ‘tools’ for ‘translation’ of written text for

coding the flight path• Complex routes >>>Complex coding• TMA procedures consumes half the database

capacity

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RNAV System Requirements

FMS Database production (5)

• At present, responsibility for coding rests with the database supplier

• Future: coding advise by the State Authority?

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RNAV System Requirements

What RNAV can do (1)

• Highly accurate lateral navigation during straight segments when within Radio update mode

• Assistance in vertical navigation• Certified VNAV control emerging• Random tracking• Smooth track intercepting

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RNAV System Requirements

What RNAV can do (2)

• Controlled turn• RF leg is emerging, but will not give all answers

to the open loop turn problems

• Fly-by turn • FMS-friendly, but requires significant freedom to

start and end the turn

• Fly-over turn• Unstable intercept next leg• Requires long stabilisation distance

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RNAV System Requirements

FMS limitations (1)

• Minimum distance between waypoints• Limitations for SID coding (often tight turns desired)• Speed control required (dominant factor)• Speed control may affect aircraft performance

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RNAV System Requirements

FMS limitations (2)

• Limitations direct after take-off• First fly-by way point minimum distance from

Departure End of the Runway (DER)• Turn delay when fly-over is programmed• Turn delay when turn at an altitude is

programmed• Destabilised route in case of fly-over coding,

unless DF leg is applied

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RNAV System Requirements

FMS limitations (3)

• Limited in general speed constraints• Only one general speed limit per airport (e.g

250 kt below 10.000 ft)

• Limited in procedure designation• Only one approach type per runway codable

(unless officially designated separately)• Only one missed approach per approach type

per runway codable

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RNAV System Requirements

FMS limitations (4)

• Limited in procedure designation• 5 characters for waypoint names• 6 characters for airway designators• 6 characters for SID/STAR designators• Transition concept applied for SIDs/STARs

may not match with Source Documentation

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RNAV System Requirements

AIRCRFAFT Owner• Aircraft owner responsible for:

• nav database contract• airline policy data• timely loading current data• assurance of integrity critical RNAV data

(requirement for RNAV)• pilot training/checking procedures for RNAV• communication via the database supplier

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RNAV System Requirements

AIRCRAFT Manufacturer• Aircraft manufacturer

• End responsibility for ‘subcontractors’ (avionica manufacturers)

• Involvement in modification of software and hardware of any system in the aircraft

• Additional aircraft performance data added to the database disk

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RNAV System Requirements

FMC Manufacturer• FMC manufacturer responsible for:

• data translation ARINC 424 into FMC language

• compatibility with all FMC’s (all update versions)

• Quality assurance process• FMC software updates

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RNAV System Requirements

DATABASE Supplier• Database supplier responsible for:

• conversion source data into ARINC 424 ‘language’

• verification of coding• quality assurance (ED 76 compliant for

RNAV)• communication/verification with sources of

the data

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RNAV System Requirements

Navigation Performance (1)

• RNAV performance aims are:1 Repeatability of the lateral path2 Flight path accuracy

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RNAV System Requirements

Navigation Performance (2)

1 Repeatability of the Lateral Path• Safety aspect

• remain within the protected airspace• Obstacle clearance• Traffic separation

• Capacity aspect• ATC reaction to navigation ‘surprises’ : >>>> increase

of separation minima• Economical aspect

• Noise abatement

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RNAV System Requirements

Navigation Performance (3)

2 Flight Path Accuracy• Significant increase in accuracy• Accuracy highly dependant on coding

applied• Significant freedom during turns

• May cause mitigating reaction by ATC• RF leg emerging

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RNAV System RequirementsAccuracy, Integrity, Continuity & Availability

• General• History: ICAO RGCSP>>RNP Concept• Four parameters to control the safety of the

total system• Many changes in definition over the years• Now also used for sensor specific systems• Responsibility for adherence rests with the

user

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RNAV System Requirements

ACCURACY (1)

• Accuracy The degree of conformance between the

estimated, measured, or desired position and/or the velocity of a platform at a given time, and its true position or velocity.

‘Where the system is’

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RNAV System Requirements

ACCURACY (2)

• Position Update Components• DME old/new (provides radio update position)

and/or

• GPS/GLONASS (provides satellite update position) (Augmentation techniques emerging)

and additionally -if any-

• IRS(-es) (provides reference position), time related• ANP/EPU/EPE warning system (in case of RNP)

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RNAV System Requirements

INTEGRITY (1)

• Integrity The ability of a system to provide timely

warnings to users when the system should not be used for navigation

‘Trusting the system that it is where it says it is’

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RNAV System Requirements

INTEGRITY (2)

• Integrity level to prevent a catastrophic failure condition less than 1*10E-9 per flight hour (JAR 25-1309)

• Integrity trough (position) error detection and identification

• Contrary to accuracy, integrity is not measurable

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RNAV System Requirements

INTEGRITY (3)• Difficult for complex systems• Even more difficult for highly software driven

systems • Integrity increased by multiple independent

system design and cross- checking between independent systems

• Independency through dissimilar design of multiple systems ?• E.g. independency of DME station selection

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RNAV System Requirements

AVAILABILITY (1)

• Availability An indication of the ability of the system to

provide usable service within the specified coverage area

‘It’s there or it’s not there’

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RNAV System Requirements

AVAILABILITY (2)

• Covers the risk of a lack of guidance at the start of the operation

• Risk mitigation through multi sensor design

• Provisions available to give timely alarm in case of loss of navigation

• Provisions to remain within a specified RNP level (RNP requirement only)

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RNAV System Requirements

CONTINUITY of Function (1)

• Continuity of Function. The capability of the total system to perform

its function without non-scheduled interruptions during the intended operation

‘It will be there or it will not be there’

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RNAV System Requirements

CONTINUITY of Function (2)

• The probability that the system will be available for the duration of a phase of operation (presuming that the system was available at the beginning of the operation)

• RAIM hole checks for the intended route• Continuity increased by multiple system

design (back-up)• Continuity controlled through multi-sensor

system design

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RNAV System Requirements

WGS 84 (1)

• Need for accurate data in WGS 84• WGS 84 technically not required for ground

based updating systems, however…..• Implementation of WGS 84 is also a matter

of increased accuracy and quality control• Position determination of FMS without

GNSS sensor is relative to the ground station

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RNAV System Requirements

WGS 84 (2)

• Problems may occur when station with a different reference datum is used

• Large deviations however should be filtered out by the FMC update algorithm

• Small differences could be accepted by the system>>Map shift

• GNSS sensored systems:• WGS 84 datum is absolutely a requirement

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RNAV System Requirements

TOOLS (1)

• Need for appropriate tools• RNAV procedure design: coding

complexity decreased• Pressure for complexity in route design

(noise driven)• Noise abatement routes over-complex

compared to conventional design• Thorough testing required

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RNAV System Requirements

TOOLS (2)

• Expert judgement for complex routes• Lap-top testing• Flight simulator check

• Maximum and minimum T/O weight• Maximum wind in strength and direction

• Actual flight trials via trial periods using designated operators

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RNAV System Requirements

ADVISES In principle, adhere to the ‘minimum distance between way

points’ tables of PANS-OPS Cater for maximum assumed wind speed Cater for different wind directions Apply sufficient distance for first way point after DER Use TF coding as much as possible Apply Fly-over as alternative but... use DF after Fly-over coding, airspace permitting Cater for delayed turns Check flight paths with different FMCs Use S.I. PDT as initial check

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RNAV System Requirements