PPRuNe Forums - Is autopilot or FD necessary for PBN RNP APCH (LNAV)

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TomasLT

28th Nov 2019 15:03

Is autopilot or FD necessary for PBN RNP APCH (LNAV)

Hi,
Looking for information regarding PBN. Have to figure-out is autopilot or flight-director is necessary on board to get operational approval for RNP APCH (LNAV). In AMC 20-27 You can find some not very clear statements, from which can be understood, that AFCS is necessary. Thanks in advance!

noptawat

30th Nov 2019 11:04

To be specific for RNP Approach or Rnav(GNSS) in which RNP not less than 0.3 NM with LNAV Minimar

Auto Pilot is NOT required, however FD is required to be followed :)

REF1: A330 / A320 FCOM-> Procedures->Special Operations -> 51 Performance Based Navigation (PBN) -> RNP APCH/RNAV (GNSS) 30 NOV 2019
REF2 :ICAO DOC9997 Performance-Based Navigation (PBN) Operational Approval Manual 2018 -> Chapter 4 Nav Spec & DOC 9613 AN/937
EASA CS-ACNS ACM 20-27
FAA AC90-105
SOP -> Procedure -> DES Prep & Approach using FINAL APP

FlyingStone

30th Nov 2019 12:54

It will all depend on what the manufacturer has managed to demonstrate to the authority.

737 with the latest FMC Update can do RNP 0.10 with or without AP.

Denti

30th Nov 2019 15:46

Well, how is it in FLS (airbus) or IAN (Boeing)? Different indication which is completely ILS alike in looks and behaviour. Considering that we can easily fly GLS/ILS approaches to CAT I limits and with a HUD in some cases to CAT III limits, why would we not be able fly an RNP approach to a lower limit if the indication system supports that?

hikoushi

3rd Dec 2019 06:19

Quote:

Originally Posted by Denti (Post 10629804)

In our fleet at least (NEOs), we have FLS, which precludes RNP approaches. RNP approaches with radius-to-fix legs requires FINAL APP mode, which does not play well with FLS. An update is supposedly on the way that will change that... but apparently FLS will still only work for straight-in approaches.

turbidus

6th Dec 2019 16:18

A characteristic of the FLS is that it can only be used for straight-in approaches. It is not compatible with curved RNP-AR approaches.
For curved approaches, crews need to undertake specific training and checking, and use the FINAL APP (or APP-DES on A350 aircraft) mode.

Airbus is working towards co-existence of the two modes so that all non-ILS/MLS approaches are flown in FLS and the FINAL APP mode remains available for RNP-AR.

H Peacock

1st Feb 2023 20:02

Does anyone know of a definitive source document re autopilot use on an RNP approach; do I have to fly it AP-in, or is it dependent upon each aircraft type’s certification?

BraceBrace

2nd Feb 2023 11:37

Quote:

Originally Posted by H Peacock (Post 11378209)

Does anyone know of a definitive source document re autopilot use on an RNP approach; do I have to fly it AP-in, or is it dependent upon each aircraft type’s certification?

Check your AFM, it should show achievable RNPs with AP and/or FD use.

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