PPRuNe Forums - View Single Post - Air Asia Indonesia Lost Contact from Surabaya to Singapore
Old 15th Dec 2015, 20:39
  #3806 (permalink)  
ExV238
 
Join Date: Sep 2015
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Alarming...

Although overspeed is not desirable in a modern transport jet, it is much less harmful than stalling it.

Talk to test pilots and certifying engineers. Modern transport jets are deliberately flown into heavy overspeed situations, and they are just fine compared to being in a fully developed stall with 40° AOA and falling like a stone.

If I could pick 50kt overspeed or 40° AOA I would always choose overspeed.
As I'm sure the poster of the above knows, Part 25 certificated aircraft are tested for structural behaviour (flutter) up to VD/MD, but not above. Above VD/MD all bets are off and the designer has no more data for you. Flutter can develop in seconds and can be catastrophic in only a few more. To take the A320 as an example, MD is approximately MMO+20 knots at FL390. If you allow your aircraft a '50 knot overspeed', then you are not only conducting experimental flight test, you're doing a research programme that's unlikely to end well.

In contrast, all Part 25 aircraft have to demonstrate safe stall characteristics, and there's no reason why AoA should develop to 40° unless you hold the aircraft into the stall. Even then it should be recoverable with the published technique for your type.

Let's all be REALLY careful what we post on this professional forum, and REALLY careful what we read and believe. Let's base ourselves on the facts. Seriously.
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