I think sometimes the Cessna stall warning tabs are affected by gravity too, not just AOA. I was in the pattern at Bishop, CA in a Cessna 340 (pressurized twin, cabin class) with a Vso of 64 (with vortex generators) flying 120 knots. It was turbulent and the stall warning horn kept going off in the bumps, checked both ASI's and GPS speed, controls felt firm, no mushing, so I ignored the warnings landed fine, checked the stall tab, it appeared to operate normally. It seems like flying into Minden or Lake Tahoe I had encountered much worse turbulence yet never had the stall warning horn. While we trust instruments, keep your mind in the loop.

On Saturday, April 23, 2016 at 8:20:32 AM UTC-7, kirk.stant wrote:

Was your stall warning going off? Because that little vane or whatever they use on Cezznas these days is just a crude on/off AOA indicator, calibrated to go off just before stalling AOA.

If it's turbulent enough to affect AOA that significantly, i would think it would be nice to know - so as to speed up enough to stay out of the stall range?

I will admit that it wasn't ever a problem in the F-4; 78 lbs/sq ft at 540 knots doesn't get bounced around much...

Information is information - AOA provides direct information, in real time, of what your wing is doing with regards to producing lift. Airspeed does not - it just tells you how fast you are moving through the air. Both are useful, for different reasons.

Ever tried a really hard slip in a modern glider? Or a K-21, even? What does the airspeed show? Hmm, it sure flies nice at zero airspeed! A properly designed AOA system would work at pretty much any realistic yaw angle, so you could slip without having to guess how fast you are going. Nice to have since the FAA still wants slips to a landing during a checkride!

(Just joking a bit there, but you get the idea...).

Kirk
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