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Old 19th Apr 2011, 21:46
  #3680 (permalink)  
Chris Scott
 
Join Date: Jan 2008
Location: Blighty (Nth. Downs)
Age: 77
Posts: 2,107
Received 4 Likes on 4 Posts
ACA190 versus AF447

Quote from PJ2 (Apr19/0714z, currently post #3646):"I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's."

PJ2 is absolutely right to remind us that wake turbulence is a very different phenomenon from turbulence in towering cumulus (or Cb storm-cells). I reckon he has experienced both, as I have.

For whatever reason, posts have been coming thick and fast over the last two or three days, and it's possible that even PJ2 may have missed something here. There are arguably at least four points of similarity between ACA190 (the Air Canada A319 wake-turbulence encounter that sensor validation kindly reminded us about) and AF447:
1) both involved Airbus FBW aircraft, whose artificial handling qualities are deliberately similar;
2) both occurred at medium subsonic-cruise altitudes;
3) both involved the PF suddenly and unexpectedly having to "hand-fly" the aeroplane, using the sidestick (the use of rudder pedals in ACA190 is another matter);
4) in both cases, for one reason or another, control laws were degraded.

Few line pilots dispense with the autopilot for regular handling practice at cruise altitudes, even in smooth conditions. Passenger comfort is our main priority. As for deliberate degradation of control laws (by selecting one or two of the 5 flight-control computers off, as someone once wanted to do on a flight with me in the early months of A320 operations), that is definitely taboo on the line.
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