AF 447 Thread No. 11
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I didn't know that an A330 was capable of flying with an IAS <60 kts.
The point is that the manufacturer of an AoA sensor can guarantee a certain accuracy only within a certain envelope. Outside that envelope any value derived from the sensor must be considered inaccurate and unreliable.
Last edited by HazelNuts39; 16th Nov 2013 at 17:50.
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At less than 1 g, sure it can do that. Without stalling too.
Outside that envelope any value derived from the sensor must be considered inaccurate and unreliable.
Brilliant logic! Best not tell the crew they are stalled then.
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Even though the speed sensor is in error?
Best not tell the crew they are stalled then.
Hazelnuts
Hold the horses!
At the moment we are discussing the inconsistency of the stall warning, right?
Due to an airspeed, which was inconsistent in itself?
And therefore rendered an available AOA indication as unreliable?
And therefore caused the aural stall alert system to tell the crew "end of stall"?
And you think, that is a logic system in itself and not worth improving?
There were much more powerful indicators to tell the crew they were stalled. They were all ignored, just as the stall warning itself.
At the moment we are discussing the inconsistency of the stall warning, right?
Due to an airspeed, which was inconsistent in itself?
And therefore rendered an available AOA indication as unreliable?
And therefore caused the aural stall alert system to tell the crew "end of stall"?
And you think, that is a logic system in itself and not worth improving?
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Due to an airspeed, which was inconsistent in itself?
And you think, that is a logic system in itself and not worth improving?
Quote:
First due to icing, later due to the high AoA
Quote:
I'm sorry if i misread your posts, but yes, you sound like you do.
Due to an airspeed, which was inconsistent in itself?
Was it inconsistent?
Was it inconsistent?
Quote:
And you think, that is a logic system in itself and not worth improving?
When did I say that?
When did I say that?
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Years ago I proposed that, if the AoA signal is lost while stall warning is active, the stall warning should continue until a valid AoA signal indicates that the AoA is less than the stall warning threshold.
However, one needs to be very careful avoid that the cure is worse than the disease. The whole issue is somewhat trivial compared to the need to avoid getting to an AoA of 42,5 degrees in the first place.
However, one needs to be very careful avoid that the cure is worse than the disease. The whole issue is somewhat trivial compared to the need to avoid getting to an AoA of 42,5 degrees in the first place.
Per Ardua ad Astraeus
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until a valid AoA signal indicates
the need to avoid getting to an AoA of 42,5 degrees in the first place.
The whole issue is somewhat trivial
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to the best of my knowledge, 447 never 'lost' a valid AoA signal?
The stall warning was lost after the captain arrived in the cockpit.
Last edited by HazelNuts39; 17th Nov 2013 at 08:45.
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That sounds suitably over-complicated.
So it never 'lost' a valid AoA SIGNAL as far as we know.
Last edited by HazelNuts39; 17th Nov 2013 at 09:18.
Hazelnuts39
The ADIRU determines the vane angle from the sensor 'resolver' values. Possibly it applies a calibration of vane angle vs body angle of attack for the flap/slat configuration. If the airspeed is less than 60 kt CAS, the ADIRU transmits the value NCD (No Computed Data) instead of the AoA value (as I understand it). The stall warning function resides in the FMEGC which uses the AoA values it receives from the ADIRU's.
The ADIRU determines the vane angle from the sensor 'resolver' values. Possibly it applies a calibration of vane angle vs body angle of attack for the flap/slat configuration. If the airspeed is less than 60 kt CAS, the ADIRU transmits the value NCD (No Computed Data) instead of the AoA value (as I understand it). The stall warning function resides in the FMEGC which uses the AoA values it receives from the ADIRU's.
To clarify my thoughts a simple example out of daily life. I'm wearing glasses like many people do. When i enter a moist room coming from the cold outside the glasses fog up. Instead of closing my eyes and being blind it has itself proved appropriate to remove the fogged up glasses and work with whatever eyesight is left.
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Why not implement a logic, where an AOA value above the highest stall onset AOA bypasses the above logic and thus keeps the stall warning active?
Last edited by HazelNuts39; 17th Nov 2013 at 11:10.
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AoA indicator.
even simpler would be providing an AoA indicator....
@HN39:
Not to be picky but stall warning resides in FWC (Flight Warning Computer) not in FMGEC.
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If you were you would read the Report first before spreading disinformation.
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This is the final report BEA for the Habsheim crash (in french .. never seen it released in english so far)
Zippyshare.com - Rapport BEA Habsheim.pdf
Zippyshare.com - Rapport BEA Habsheim.pdf
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Folks,
We've had a few complaints about introducing Habsheim in this thread. If folks see a need to discuss, please raise a second thread to keep the two easier to follow.
We've had a few complaints about introducing Habsheim in this thread. If folks see a need to discuss, please raise a second thread to keep the two easier to follow.