AF 447 Thread No. 12

[Chris Scott]

Quote from Owain Glyndwr:
"or
(3) abiding by the vane manufacturer's DDP which gave the limits on output validity for the vanes?"

Thank goodness for the presence of an engineer to remind one of the obvious! In which case, perhaps the vane manufacturer might be politely asked to reconsider the DDP and/or review the design?

Hi vilas,
I entirely share your reservations about the chances of the AF 447 crew having benefited from an AoA indication that morning. The actions of the PF in making or allowing the a/c to climb from a stable cruise regime were so bizarre that the inclusion of another parameter to those currently available to him is perhaps unlikely to have improved his situational awareness. There remains a slight possibility, however, that the presence of an AoA gauge might have informed the captain of the deep-stall regime that was in force when he entered the cockpit during the descent. Whether there was sufficient altitude to effect a recovery at that stage, given the application of immediate and correct action, has been the subject of some speculation previously.

CONF_iture reminds us of the anomaly by which the stall warning is inhibited when the AD detects an IAS below 60 kt, which may or may not be false. That is something that needs to be addressed.

Another problem is that, on any type of a/c, the trouble with aural/tactile stall warnings is that they remain at the same intensity regardless of how much the stall AoA has been exceeded. I'm wondering if the sudden appearance of an AoA indicator showing clearly how much the AoA is above the stall might be useful.

In the case of AF 447, there would have been periods of stall warning activity where such an AoA gauge could have shown the crew that the stall AoA had already been exceeded by a very large amount. This MIGHT have finally alerted one of the pilots to the developing situation. Whether that would have resulted in his taking the correct recovery action is, of course, another matter.