Plane & Pilot
Saturday, October 1, 2005

The Touchdown Set-Up

Be prepared for any last-minute corrections when landing

About 14 seconds after touchdown, the aircraft’s flight data recorder (FDR) showed that the right wing suddenly moved about six degrees lower. About the same time, the CAWS landing-gear alert began to sound, which repeated until the end of the recording.

At about 12:26:25, the captain declared, “Here we go,” and the airplane began to veer off the right side of the runway. Five seconds later, the airplane came to rest in the grass off the right side of the runway.

At the NTSB’s request, the Weather Sensing Group at the Massachusetts Institute of Technology at the Lincoln Laboratory reviewed the weather data. According to the report, there was no evidence of a horizontal wind shear or other hazardous conditions near the runway at the time of the accident. The report noted a pattern of buoyancy waves aloft that might have been responsible for the CAWS wind-shear warning recorded on the airplane’s CVR.

The NTSB calculated that the airplane was yawed about 5.4 degrees nose-left of the runway heading when it touched down. The NTSB also calculated that the cockpit was about 20 feet right of the runway centerline. Although the FDR pitch data showed no evidence of a flare before the airplane touched down, the FDR elevator position data showed that the elevator moved from about 2.75 degrees to 12.75 degrees airplane nose up almost immediately after the left main landing gear touched down, just as the right main landing gear touched down. The study also revealed that the airplane’s longitudinal axis was not aligned with its direction of flight or the runway when it touched down. Rather, the nose of the airplane was aligned about 6.5 degrees left of the airplane’s ground track.

FedEx’s MD-11 and MD-10 flight manual says, in part: “Crosswind landings are accomplished by flying the final approach in a wings-level attitude with a crab into the wind. At approximately 200 feet AGL, align the fuselage with the runway by smoothly applying rudder and maintain runway centerline by lowering the upwind wing.”


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