PBN and RNAV concepts

PBN and RNAV concepts

Rabat, 16/27-03-2015

Target:

Learn basic concept on PBN and RNAV.

2 NOT FOR COMMERCIAL PURPOSES

Concepts

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Part 1: PBN concept Part 2: RNAV, RNP

Part 3: FTE (Flight Technical Error)

Part 4: BV (Buffer Value)

Part 5: Obstacles clearance area

Part 6: Additional fixes

NOT FOR COMMERCIAL PURPOSES

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PAN OPS Reference

Part III – Section 1 – Chapter 1

PAN OPS Vol II Sixt Edition


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RNAV can be defined as a method of navigation that permits aircraft operation on any desired course:

within the coverage of station-referenced navigation signals, or

within the limits of a self-contained system capability, or

a combination of these.

Estimated position is detremined using GNSS (GPS, EGNOS, ecc.), IRS, DME/DME

• The position amendment is obtained using available sensors

• FMS flight management is based on onboard database

RNAV navigation

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PBN Concept Performance-based navigation (PBN) is defined as a type of area navigation (RNAV) in which the navigation performance requirements are prescribed in navigation specifications. A navigation specification is defined as a set of aircraft and aircrew requirements needed to support PBN operations within a defined airspace.

There are two types of navigation specifications: a) RNAV specification. A navigation specification designation that does not include requirements for on-board performance monitoring and alerting. b) RNP specification. A navigation specification designation that includes requirements for on-board performance monitoring and alerting.


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PBN Concept Performance-based navigation (PBN) is defined as a type of area navigation (RNAV) in which the minimum navigation performance requirements are prescribed in terms of: • Accuracy: difference between real position of a/c and estimation of on board

RNAV system NSE Navigation System error is the difference between the actual

and desired position in fault free conditions TSE Total System error is the difference between the actual and

desired flight path in fault free conditions

• Integrity: the ability to give timely warnings when the system cannot safely used

• Availability: of the total system

• Continuity: the ability of the navigation system to provide its service without interruption during operations


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PBN PBN together with Communication, Surveillance and ATM are the keys concept to define the AIRSPACE concept. ELEMENTS: • Air and ground side of the

navigation infrastructure: Radioaid, IRS and GNSS

• Navigation specification (air side): Performance required in terms of RNAV capability and requirements in terms of crew training

• Navigation application: Procedure/Routes that can be designed in a n Airspace related to the 2 above elements.


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Conventional vs PBN Conventional navigation

PBN Navigation

BENEFITS

•System tested and reliable

• Easy monitoring of the infrastructure on the

ground

BENEFITS

• Design flexibility

• Constant protection depending on the

type of requirement (RNAV 1 , RNAV 5 ,

RNP ( 0.3 or lower) )

• Rationalization of the ground radioaid

• Decreased flight time

• Best environmental efficiency

DISADVANTAGES

• Rigid system (obligation to refer to the

ground radioaids)

• Any airspace require an increased

distance from reference radioaid

DISADVANTAGES

• GPS constellation unmonitored

• Possibility to handle mixed traffic

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Conventional Navigation vs RNAV Navigation - Example

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Conventional Navigation vs RNAV Navigation - Example

PBN

Navigation Specifications and Applications

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RNAV vs RNP

Both RNAV and RNP operations could be described in terms of

navigation performance (e.g. accuracy), RNP operations can be

identified by the capability of the on-board navigation system to monitor

in real time the achieved navigation performance and to alert the

operating crew when the specified minimum performance appropriate to

a particular operation could not be met. This additional functionality

provided by RNP allows the flight crew to intervene and to take

appropriate mitigating action (e.g. a go-round), thereby allowing RNP

operations to provide an additional level of safety and capability over

RNAV operations.


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Navigation specification per flight phase

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Navigation specification per flight phase Notes

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Flight Technical Error FTE

The 95 per cent FTE values from which the design criteria for PBN applications have been derived are based upon the following formulae:

For RNAV, FTE=1

2 required navigation accuracy

For RNP≥0.5, FTE=1

2 RNP

For RNP≤0.5, FTE=463M (0.25NM)

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Buffer Value BV To address excursion beyond a 3𝜎 values an additional buffer value based

upon A/C characteristics and phase of flight is taken in account.

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Protection Area Area semi-width ½ A/W= 1.5 XTT+BV

XTT=cross track tolerance

XTT is the 2σ cross-track tolerance value (known as TSE)

Merging 30°going from larger to smaller area

Merging 15°going from smaller to larger area ATT=along track tolerance

More than one navaid type can be used on a procedure (e.g. DME/DME and GNSS for RNAV 1), the XTT, ATT and area semi-width shall be calculated for each specific navaid type and the obstacle clearance shall be based on the greater of these values.

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Merging Area and ATT

ATT= along track tolerance

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Additional Waypoint on straight segment

To allow implementation of specific constraints (e.g. a speed restriction, a change of altitude or a reporting point for ATC purposes) some waypoints may be added within a straight segment.

Due to the flyability, pilot workload, navigation database size, etc…., the following needs to be taken into account when add waypoints:

• Generally, no more than two additional waypoints should be

specified within a straight segment (to be not considered for the calculation of the lateral protection area and are defined as fly-by waypoints)

• Altitude changes and speed restrictions shall only be applied when

operational benefits are expected.

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Step down fixes Criteria contained in Part I, Section 2, Chapter 2, 2.7.3, “Stepdown fix” and 2.7.4, “Obstacle close to a final approach fix or stepdown fix” relative to stepdown fixes apply. The SDF location shall not be considered for the calculation of the lateral protection area.

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FTA and 15% plane

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PBN «elements»

RNAV and RNP Navigation Specifications FTE (Flight Technical Error) and BV (Buffer Value)

Protection area

Additional fixes (e.g. SDF)


NOT

FOR

COM

MER

CIAL

PURP

OSES

PBN and RNAV concepts

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Transcript of PBN and RNAV concepts