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Old 5th Jun 2009, 14:35
  #133 (permalink)  
Blacksheep
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The only way anyone will know for sure what happened is when the FDR and the CVR are brought up from the bottom of the ocean.
They might tell us waht happened but they won't tell us why. Even the best accident investigations rely heavily on data "interpretation" - another word for speculation. For the time being we have ACARS Data that tells us a great deal of what system failures occurred and these data at least permit our speculation to point towards a reasonable conclusion concerning the root cause.

Regarding the difference between Mmo and stall speed at high altitude, Mmo is set low in certification to ensure that the aircraft is kept clear of the edge of the envelope. There is disagreement between the authorities as to where it should properly be set - for example, the B767 Mmo is 0.84 by UKCAA rules and 0.86 by the FAA rules. The book figures are not clearly defined knife-edges.
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