Can the FPV be used to determine AOA

[Winnerhofer]

Airbus AOA Display

Is AOA indicator still available on Airbus i.e. PFD-integrated and not separate like early A320s?

[Kefuddle]

Chris,

The difference between Pitch and FPA certainly gives a rough guide to AoA, particularly changes of AoA. As has been said by others, it should be correct in still air, but becomes increasingly inaccurate as the headwind or tailwind component increases. That's because FPA is in relation to the earth, not the airmass. (So vertical movement of the airmass, particularly a microburst, will also cause inaccuracy.)

Thanks for that, that's cleared up the confusion for me.

Regarding turbulent air, mictorbursts etc. I imagine one would experience large transient changes which I don't think would be particularly useful. The rise and fall of the barbers pole would probably provide the best awareness or critical AoA and given that TOGA FD guidance will attempt to maximise climb performance possibly at intermittent stall warnings averting one's gaze to an AoA indicator would probably not be all that helpful.

We have the AoA indicator on he HGS (737). But then we know what power settings and pitch attitude combination to use. Without specific practice/training on adjusting speed and pitch with sole reference to the AoA would anybody actually use it? Maybe as a crosscheck as long as you it doesn't then become confusing in an unusual situation.

[BARKINGMAD]

"I've never seen........"

Probably because the tight-fisted beancounters who had the FINAL SAY , over the heads of your flight ops and training requirements, on what would be bolted into your future 'frame, decided to pass on that option.

What do you think the AOA probes on most modern shiny jets measure?

The info is there, the guage/dial/EFIS Iinterface is just not there because THEY don't think it's useful/safer/necessary.

An engineer could correct me, but you might even find the wiring and the multi-connector plug (hopefully) safely tied up behind your instrument panel(s). All that's needed is a suitably placed hole and tens of thousands of local currency to your friendly xAA to certify it's fit for use.

Simples!

[Winnerhofer]

BUSS

So does BUSS have adequate info to substitute for an AOA display?
What's Boeing's answer to BUSS?

[Denti]

Sadly the BUSS seems to be cheap enough that it is practically a standard equipment, whereas the boeing AoA indicator seems to be so expensive that nearly no airline selects it.

[vilas]

OK 465
What FPV are you talking about? Can you explain that? BUSS uses angle of attack information through IR switches instead of ADRs but there is no FPV.

[OPEN DES]

FPV is never purely inertial. (Apart from the mod you mentioned earlier possibly, dont know tbh)
In all other cases FPV uses Vzbi (baro-inertial V/S) as the input, same as V/S on the PFD under normal circumstances.
Hence the UAS (unrel air speed) procedure mentions not to use the FPV whenever air data is affected.
A question (slight thread creep) for the more knowledgeable among us:
Since what mod of the BUSS does the a/c revert to direct law with a subsequent reversion to alternate law once the flaps are selected??

Thanks

[OPEN DES]

Ok that clears things up.
I was always under the impression that when Vzbi wasn't available that AoA vs pitch was used to provide 'degraded' FPAair data to the FPV (relative to air rather than geometric).
In the sims i use when we fly with the BUSS the FPV flag shows up which implies that there is no inertial FPV. Since what mod is a pure inertial FPA available to provide data to the FPV?
Thanks!

[A33Zab]

Hybrid FPA

MOD 202164 (A330)
MOD 153528 (A320)

The FPV is based on the FPA.
When ADR data is not available the baro-inertial parameter (Vzbi) is missing to calculate the 'classic' FPA. (FPA = arc tan(Vzbi/GS)

After the mod, if the baro-inertial is not available, this parameter is replaced by GPIRS (a mix of Inertial and GPS pos data)
This FPA is called the hybrid FPA.

Link to previous post

[vilas]

OK465 &A33Zab
I saw the MOI but in UAS procedure FPV plays no part what so ever. You go by memory items then QRH, ECAM and QRH again. Below 20000 with all ADRs OFF you just fly the green.

[BARKINGMAD]

...........Ladies & Gentlemen of the jury, l repeat the question yet again.

Has the THS position check been included yet in the UAS recall items?

And if not, why not?

Refer to accident reports various, exhibit #94 etc etc.......