PPRuNe Forums - View Single Post - AF 447 Thread No. 5
View Single Post
Old 27th Jul 2011, 00:09
  #745 (permalink)  
JD-EE
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Likes: 0
Received 0 Likes on 0 Posts
Airtren, IMAO the plane's software declares stalls inappropriately. The stall at 2 h 10 min 05 is likely spurious related to the airspeed indication dropping even though the plane is still flying at altitude with very little real speed change.

If it was real the plane canceled it inappropriately when the real velocity was still high and the indicated air speeds were below 60 kts. It should be 'obvious' to the software that if the plane was really stalled, it's inertially derived ground speed had not changed, that it was still stalled.

If it was a spurious warning the plane should have cross checked inertial data with air speed data and decided the warning was spurious.

The warning at 2 h 10 min 51 was probably real. By then the pilot was confused by the on again off again stall warnings and not sure if this one was real.

Couple this with the PF's initial apparently inappropriate action and I'm not sure what I'd expect the PF to do.

What I really want to know is WHY the PF might have might have made this apparently inappropriate action. If he was still thinking he clearly thought it was the right thing to do. Once PF had the plane at 16 degrees pitch and an AoA of 60 degrees I am reasonably convinced it was all over. There was not enough altitude to get the plane back into a flight configuration based on the NASA curves posted here in the past.

So once the pilot made that inappropriate move the plane's responses to his actions certainly did not help. PF needed something to beat into his brain (a physical slap in the face?) to convince him he was stalled. Turning off the warning is not going to do that.
JD-EE is offline