Saudi Arabian investigators have reached the conclusion that the pilots of the Lufthansa Cargo Boeing MD-11F that crashed on landing at Riyadh on July 27th, 2010, failed to recognize the landing bounce that occurred before a sequence of hard touchdowns and the destruction of the aircraft.
The investigation report indicates that as the aircraft conducted a landing approach to Runway 33L, it flared at a low height for its 207t landing weight. The aircraft touched down with a sink rate of 780ft/min, which is extremely higher than the usual 120ft/min, hence creating a 2.1g impact that caused the MD-11F to bounce.
The Saudi General Authority of Civil Aviation (GACA) stated the landing was still recoverable at this point, but the crew did not recognize the bounce and did not use the recovery procedure that requires pilots to apply thrust to control the rate of descent and continue with normal landing.
After the first touchdown, the aircraft bounced to a height of 4ft, and the captain pushed the control column drastically forward, which reduced the pitch. Due to main-gear spin-up, the MD-11F’s spoilers had also started deploying, further reducing the angle of attack. The aircraft’s lift was weak due to these combined dynamics. Although the pilots pulled on their control columns, the aircraft hit the runway a second time with a sink rate of 660ft/min.
The MD-11F’s nose-gear rebounded from the 3g impact, causing a 14° pitch-up as the aircraft bounced a second time, to 12ft. With the pilots pushing the control column forwards and then pulling back, a third hard impact of 4.4g occurred. This damaged fuel lines and ruptured the fuselage aft of the wing, igniting a massive fire.
"While the first touchdown resulted in a bounce, the landing was recoverable," said the GACA. "The severity of the subsequent touchdowns was not a consequence of the first touchdown, but primarily a result of the pitch angle during the bounces, which resulted from the actions of both flight crews on the control column."
Although there was severe structural damage to the aircraft when it swerved off to the left side of runway and consumed by the blaze, both pilots survived the accident.