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Autoflight limitation.NPA

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Autoflight limitation.NPA

Old 26th Nov 2021, 04:43
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Autoflight limitation.NPA

Hello everyone ! Sorry if this thread was rised before.
So A320fam AFM/FCOM limitation - AFS - FMS section states that Conventional navaid approaches may be performed in nav/app nav/final app modes with AP/ FD is used and GPS PRIMARY is available with ground based navaid or airborn equipment inoperative or not installed ,provided an operational approval is obtained..
​​​​​​I have one question about this.
Where/ how can I check this approval is obtained?( I work in RU , our regulations are mostly the same as ICAO except differences in State rules & proc-s. and my company use EASA Air ops methods for AOM)
Could someone make it clear?) Thanx!
​​​​
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Old 26th Nov 2021, 05:35
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It's a vague and void statement. Mere declaration of the planes capability, but no template exists for such approval.

The airline need to build it with their CAA, the sentence itself is a form of no-technical-objection from the OEM.

Some might say that it is illegal, against all airmanship, and dangerous.

Others know how to fly the 2NDB to Ulyanovsk at 5:30 a.m. in late November.
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Old 26th Nov 2021, 05:44
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Got it! You've justified my assumbtion. It seems that it's not possible to recive a Clearance for VOR appch from ATC , where VOR is unserviceable
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Old 26th Nov 2021, 05:54
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The clearance needs to be from the authority and not from ATC. Technically nothing dangerous because managed approach doesn't track the VOR flies the coded track and GS. Perhaps at certain airfields there may be safety issues which need to be catered for before such approval.
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Old 26th Nov 2021, 06:03
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"The clearance needs to be from the authority and not from ATC"
I know

Speaking about managed appch guidance you're correct, but for degraded navigation you need your refence navaid to be operative to check your lat/vert position, if this navaid or your airborne equipment is inoperative, how could you check it?
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Old 26th Nov 2021, 06:10
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Use the *ACTIVATE ALTN prompt from MCDU page.

Translation filter alert: Clearance / authorisation.
Any such authorization need to come from the CAA. (vilas: concept)
It's not likely the ATC would give you clearance for a NAVAID based approach that is U/S (sergei: manouevre).

You are both in agreement.
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Old 26th Nov 2021, 06:23
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I like your funny bone made me laughing
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Old 26th Nov 2021, 12:08
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RNP Approaches don't have a backup nav aid what about that? Some ground work will be needed for the VOR approach regarding terrain etc before it can be cleared as good enough without reference nav aid. But not at random.
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Old 26th Nov 2021, 13:19
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Speaking about RNP Appch , if you have problems with navigation i.e. GPS PRIMARY lost on both MCDUs , NAV FM POS DISAGREE etc. you cannot continue unless Visual contact is established. Whereas with conventional navaid appch permits you continue with TRK-FPA down to minima , and the only one source that may help you to check your path is the navaid approach based on.
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Old 26th Nov 2021, 13:33
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An Airbus does not normally fly a VOR approach procedure. It flies a FMS guided overlay approach. The aircraft wouldn't know or care that the VOR is working or not. This is obviously provided you have GPS Primary. The legality to fly a NDB or VOR without the station working lies with the regulator. (see FAA C300 approval). I'm not sure if OpsSpec C300 have been cancelled or superseded.

OpSpec C300 gives authorization to conduct 14 CFR part 97 non-directional
radio beacon (NDB), NDB/distance measuring equipment (DME), very high frequency (VHF)
omni-directional range (VOR), and VOR/DME instrument approaches using Area Navigation
(RNAV) as a substitute means of navigation.
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Old 26th Nov 2021, 14:04
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Sergei.a320

We are going round in circles. The issue was the approach nav aid not being available for the approach. So as I said it can be done with GPS accuracy subject to approval, now GPS not available so obviously GPS approach rules will apply and approach cannot be continued.
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Old 27th Nov 2021, 14:24
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T54A

Thank you for this, active or not. My first sentence from #2 post is rightfully challenged.
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Old 4th Dec 2021, 16:56
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You don't even have to have "GPS Primary". For us NAV ACCURACY HIGH is sufficient.
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Old 4th Dec 2021, 20:56
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Back in the day we were approved to fly overlay approaches with the underlying navaid inop with just classic 737s on DME/DME updating alone (no GPS installed, the TAWS had its own GPS not connected to the FMC), as long as ANP was below 0.3 NM. Never had to do it, but it was a point in our books. That provision carried over to the NGs (and yes, the A320 as well: ACCURACY HIGH sufficient), but still, never had to do it in the real world. That said, more recent opened airports do not have a conventional NPA as backup anymore, just RNP approaches.
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Old 6th Dec 2021, 15:13
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Originally Posted by Amadis of Gaul View Post
You don't even have to have "GPS Primary". For us NAV ACCURACY HIGH is sufficient.
Due to the nature of the post, I was assuming there would be no ground based stations available. I don't think you can fly a NPA on IRU FMS update alone. Hence the requirement for GPS Primary. I could be wrong.
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