Can the FPV be used to determine AOA
Join Date: May 2013
Location: London
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Chris,
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.
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.)
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.
Last edited by Kefuddle; 18th Aug 2014 at 09:13. Reason: Typo
Join Date: Mar 2007
Location: Another Planet.
Posts: 559
Likes: 0
Received 0 Likes
on
0 Posts
"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!
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!
Join Date: Mar 2001
Location: I wouldn't know.
Posts: 4,498
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: Apr 2004
Location: United States of Europe
Age: 40
Posts: 502
Likes: 0
Received 0 Likes
on
0 Posts
Can the FPV be used to determine AOA
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
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
Join Date: Apr 2004
Location: United States of Europe
Age: 40
Posts: 502
Likes: 0
Received 0 Likes
on
0 Posts
Can the FPV be used to determine AOA
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!
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!
Join Date: Jun 2009
Location: somewhere
Posts: 451
Likes: 0
Received 0 Likes
on
0 Posts
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
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
Last edited by A33Zab; 18th Aug 2014 at 04:07. Reason: Added A320 mod
Join Date: Jun 2007
Location: Wanderlust
Posts: 3,407
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Join Date: Mar 2007
Location: Another Planet.
Posts: 559
Likes: 0
Received 0 Likes
on
0 Posts
...........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.......
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.......