A320 NPAs in Final App with FD guidance to touch down?
Thread Starter
A320 NPAs in Final App with FD guidance to touch down?
I stumbled across a youtube video showing an A320 flying a RNP RF approach to Brisbane runway 19. They fly the approach in Final App with flight director guidance. No minimums are entered into the box and the flight directors are on right until touchdown which seems very odd to me, with a downgrade to the basic modes occurring down over the threshold.
Is this an approved procedure in Australia, or just a bit gash? I'm not trying to point fingers, but am just genuinely wondering if this is SOP?
A320 Cockpit Landing Video
Brisbane RWY 19 RNP-P Approach chart
Is this an approved procedure in Australia, or just a bit gash? I'm not trying to point fingers, but am just genuinely wondering if this is SOP?
A320 Cockpit Landing Video
Brisbane RWY 19 RNP-P Approach chart
Being an RNP RF (P-RNAV) approach, is it not a precision approach rather than a non-precision approach?
Usually an RNAV GNSS/RNP approach is a NPA, but I know there are other RNAV approaches out there (RNP AR and LPV for example) which have much lower minima, which perhaps are precision.
If so, that would explain why FDs on.
Usually an RNAV GNSS/RNP approach is a NPA, but I know there are other RNAV approaches out there (RNP AR and LPV for example) which have much lower minima, which perhaps are precision.
If so, that would explain why FDs on.
Thread Starter
Surely a precision approach is only one that is referenced by ILS/MLS/GLS guidance?
I attached the chart with the minima for reference. It's about 350ft AGL and the RNP value is 0.3nm so it's certainly a non-precision approach. It's also flown in FINAL APP which is a non-precision approach mode on the airbus. An RNP value of 0.3nm represents >500m precision, which is not even nearly good enough for the wheels to find the runway.
I appreciate that the reality is that GPS is more accurate than 500m of resolution. Although, the lowest P-RNAV minima I have come across is RNP 0.1 (Innsbruck, Funchal, Gibraltar etc). At 0.1nm, they still represent a non-precision approach.
Perhaps I've fundamentally misunderstood something, but I'm pretty sure this is odd.
I attached the chart with the minima for reference. It's about 350ft AGL and the RNP value is 0.3nm so it's certainly a non-precision approach. It's also flown in FINAL APP which is a non-precision approach mode on the airbus. An RNP value of 0.3nm represents >500m precision, which is not even nearly good enough for the wheels to find the runway.
I appreciate that the reality is that GPS is more accurate than 500m of resolution. Although, the lowest P-RNAV minima I have come across is RNP 0.1 (Innsbruck, Funchal, Gibraltar etc). At 0.1nm, they still represent a non-precision approach.
Perhaps I've fundamentally misunderstood something, but I'm pretty sure this is odd.
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Irrespective of the minima ILS GS guidance continues to touch down and irrespective of the accuracy the NPA guidance is not linked to touchdown. As a procedure FDs are to be switched off when they cannot be followed. So what is shown in the video is non standard.
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If it's company procedure then you must be loyal to your pay cheque. May be too much distraction at low minima to switch off FD, select bird and set RW track. But Airbus doesn't teach nor recommend that way. GPS approaches are moving towards auto land in future.
Last edited by vilas; 2nd Dec 2017 at 17:49.
Surely a precision approach is only one that is referenced by ILS/MLS/GLS guidance?
I don't fly the 'bus but, if the FDs are providing vertical guidance on the Baro-VNAV path and (pretty accurate) lateral NAV guidance, why wouldn't you leave them on?
Leaving FDs on in HDG/VS mode is SOP at this operator flying an RNP AR approach.
That voice...
FINAL APP remains engaged until the MAP on the recent FMS standard, rather than reverting to HDG V/S at MDA-50.
Vilas, The most recent Airbus guidance for the 1A standard is that you now have the option the leave FINAL APP mode engaged, however the AP must be disconnected by 250’. It works fine when the MAP is at the threshold.
Vilas, The most recent Airbus guidance for the 1A standard is that you now have the option the leave FINAL APP mode engaged, however the AP must be disconnected by 250’. It works fine when the MAP is at the threshold.
I don't fly the 'bus but, if the FDs are providing vertical guidance on the Baro-VNAV path and (pretty accurate) lateral NAV guidance, why wouldn't you leave them on?
Again drifting to Boeing but if the profile in the FMC ties in with the published profile we generally leave the FDs on, with the usual caveat/briefing about handling any possible mismatches with any VGSIs due to temperature.
As has already been said. There is no objection from Airbus. It is in the FCOM. So why wouldn't you do it that way.
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The approval to use FD for NPA below minima is quite new but is also only applicable under certain conditions like eg for Final App, Final must be aligned with runway track as otherwise the guidance won’t be relevant and keeping in mind that below minima visual references are the primary references for landing like for any kind of approach...
There is an Airbus document called: « Flight Operations & Training Regional Seminar: Use of the AP and FD below minima for Non Precision Approaches » that a fellow sent it to me which explains quite nicely this new procedure and limitations. If anyone interested, PM me and I will email it to you.
There is an Airbus document called: « Flight Operations & Training Regional Seminar: Use of the AP and FD below minima for Non Precision Approaches » that a fellow sent it to me which explains quite nicely this new procedure and limitations. If anyone interested, PM me and I will email it to you.
Last edited by pineteam; 5th Dec 2017 at 03:28.
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I'm not an Airbus man, but this or similar topic has been discussed previously in general terms. It is also a 'discussion point' on B737NG family between various training dept's whether to switch off FD's when visual on NPA after a VNAV/LNAV or RNAV approach. My curiosity is why do you need an FD at low level when visual?
The approval to use FD for NPA below minima is quite new but is also only applicable under certain conditions like eg for Final App, Final must be aligned with runway track as otherwise the guidance won’t be relevant and keeping in mind that below minima visual references are the primary references for landing like for any kind of approach...
The approval to use FD for NPA below minima is quite new but is also only applicable under certain conditions like eg for Final App, Final must be aligned with runway track as otherwise the guidance won’t be relevant and keeping in mind that below minima visual references are the primary references for landing like for any kind of approach...
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My recollection may be faulty, but I believe the Turkish crew that when into the mud at VNKT was criticized for leaving the FD on below DA.
