stall warning, displays, AoA sensors, BEA comments
Thank you, Wozzo, very interesting press release. Seems that some BEA investigators are concerned about some of the same things that several here are, as well. And it's not all strictly pilot error or strictly aircraft system design.
Thank you A33Z for the link to the English version of the report.
- The lack of discussion on the CVR concerning the stall warning puzzles me.
- An AoA indicator is "nice" to have, but we must examine the flight conditions it is intended to support. 'bird, Retired, Smilin' and Gums can testify that the AoA "bracket" in the HUD or the "indexer" lights were extremely valuable for approaches ( especially on the weaving deck of a large boat, heh heh). We didn't need to calculate airspeed to a knot, and we routinely landed at various weights depending upon our external loads. 'nuff said about that.
For a commercial airliner, we don't have the same requirement. Nevertheless, the AoA is very important for stall warning and recovery. The plane produces lift according to AoA and dynamic pressure!!! You can stall at many knots faster than the manual numbers for one gee.
So placing a new indicator in the displays is not a biggie for this ol' dinosaur. seems the 'bus has enough confusing displays as it is.
Use of AoA other than a display is another matter.
- Ask the above pilots if the AoA sensors ( vanes or cones) worked below 60 knots. Even if the AF447 suckers were bouncing around a bit due to an extreme AoA, I'll bet they showed a high AoA, and were not flipping back and forth from plus 30 deg to minus 30 degrees.
For the FBW system to ignore AoA below 60 knots does not seem right. Most military planes use the weight-on-wheels switch to display or even use AoA.
Further, how was the stall warning being sounded if the system had disregarded both speed and AoA?
No doubt training and manufacturer claims will come to the fore here. After all, we're "protected", right.
"We're going down, sir"
"O.K., command the plane to go up"
" I am doing that, sir, but she keeps on descending"