Old 24th Jan 2012, 23:10
  #1152 (permalink)  
Join Date: Jan 2008
Location: uk
Posts: 832
Originally Posted by BOAC View Post
I am still not understanding

It is driving me towards a 'speed' marker (green)?
It cannot itself compute speed due to failures?
How does it compute the green marker?
How does it know when I have got there?

As far as I can see this is AoA driven. The AoA is too high. What is needed is reduction in AoA in fairly short order, not just an increase in 'speed' towards a dubious green mark.

Would not a 'DOWN' arrow, flashing perhaps, on the AI be far simpler and realistic? After all is is a matter of simplicity to compute an AoA at any altitude/Mach at which the wing will unstall.
Before you've managed to stall, it's more of a green band than a mark, which might be clearer what to do with it.

[images credit to google search and a site I know nothing about - but it's not mine, just to be clear]

I think this is more or less an AoA indicator dressed up as a speed tape, but I think it does do the "compute an AoA at any altitude/Mach at which the wing will unstall" without the pilot having to remember or read tables (I guess).

By the time you've been pulling up through the stall warning for best part of a minute, it's going to look like the previously posted image and probably isn't helpful (green ? what green, where ?). But if you kept it in the green in the first place, you wouldn't have that problem.

Also, look at the conventional AoA gauge (which option AF didn't give them either):

At the same point in the timeline, that needle would have been firmly pegged at 25, and the size of the nose-down inputs they made would not have shifted it. Pull or push, the needle doesn't move - must be broken gauge... no ?
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