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Old 23rd Mar 2009, 02:06
  #40 (permalink)  
Weapons_Hot
 
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More thrust, less elevator with a bounced landing

Rainboe - you are partially correct.

The elevator authority on touchdown on the MD11 is certainly adequate to meet this type of problem (bounced landing). The contributing factors for this type of catastrophic result are: generally the throttles have been commanded closed (function of Auto Throttle System (ATS)), and the wing is a "critical" wing in such that there is little to no "ground effect" produced, and a tendency to pitch down and then immediately pitch up, which will drive the nose gear and then main gear back to the runway, with a possible >3g force. At the same time, speed/lift is rapidly decaying, which will result in less control surface authority.

A typical reaction to a bounced landing is a tendency to pitch down to "settle" the airplane, which with the MD11 is a no-no. I am aware of at least one carrier that regularly practices bounced landings in its simulator and on good authority of a couple of its drivers, their policy in relation to a bounced landing, is to go-around - GA thrust, pitch attitude 10 degrees NU, and hold that attitude until 50 ft RA (apparently to negate a tail strike).

A sad day indeed, but the result of the investigation will probably discover poor, if any, bounced landing technique being applied in this accident, exacerbated by gusty conditions.
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