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Old 2nd Aug 2011, 00:01
  #1284 (permalink)  
JD-EE
 
Join Date: Jun 2009
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jcjeant, the stall alarm was reliable as long as the PF recalled the overly complex set of rules for the stall alarm being suppressed.

this is the sort of logic I contemplate
If the plane is in the air (no weight on wheels or wheels retracted)
then
if airspeed is valid and below threshold
then
alarm: stall stall
else
then (airspeed invalid)
if stall was on
then
alarm: stall stall
else
then
if ground speed has dropped gt 150 kts in the last minute
then
alarm: stall stall
Numbers need to be teased out somewhere. Even logic as simple as this is better than what the have now, as I see it:
If the plane is in the air (no weight on wheels or wheels retracted)
if airspeed is valid and below threshold
then
alarm: stall stall
else
then (airspeed invalid)
if stall was on
then
alarm: stall stall
(A perfect solution is hard to derive and requires AoA and other criteria. I'd also put some hysteresis on the warnings so that they're a little harder to trigger and a little harder to un-trigger.)

(Sorry about the formatting - it's best I can do with this interface in a reasonable amount of time.)
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