Pilots, Not Landing Gear, Faulted in Crash

Air Safety Week, May 30, 2005

Hard landing stressed gear

The landing gear on a Federal Express MD-10 that crashed in Memphis in 2003 did not break because it was weak, but because it was overstressed, according to the National Transportation Safety Board (NTSB).

Investigators concluded that a hard landing by the first officer, the pilot flying, in the Dec. 18, 2003, crash stressed the right main landing gear beyond its design, which resulted in its collapse and the airplane veering off the runway. The airplane burst into flame, forcing the two-person crew and five other FedEx pilots flying as passengers to make an emergency evacuation.

The landing gear has been exonerated, despite the fact that a number of DC-10's and variants of that design have experienced failed landing gear, including a FedEx MD-11 accident at Newark in 1997 and a Mandarin Airlines MD-11 landing at Hong Kong in 1999 (see ASW, Aug. 30, 1999).

Acting NTSB Chairman Mark Rosenker said, "If the accident crewmembers had applied techniques in accordance with their training, the landing would have been uneventful."

The flight, Flight 647, was a check ride for the first officer, who had experienced an altitude deviation on a previous flight. Her technique was being evaluated by the captain, who was serving as both check airman and pilot in command. Hired by FedEx in 1996, she had achieved type rating on the MD-11 in 1998. At FedEx, pilots rated in the MD-11 are also qualified to fly the MD-10, which is a shorter version of the plane with two main landing gear rather than three.

She had been in a left crab, but was lined up momentarily with the runway, albeit to the left of the centerline, moments before touchdown. However, the flight data recorder (FDR) indicates that the airplane was a bit high and that the aircraft experienced an unusually high vertical speed. As a consequence, the right main landing gear experienced a vertical speed of 14.4 feet per second (fps). This was more than the 12.5 fps experienced by the left main landing gear. The design limit was 10 fps, and the demonstrated reserve energy was 12.0 fps, which the right gear clearly exceeded.

The gear collapsed during the landing rollout, and the plane fell into its right wing, where friction with the ground pulled it to the right and off the runway.

NTSB investigators attribute the accident to improper crosswind and flare techniques by the first officer and the captain's failure to take corrective actions. "The captain remained silent as the approach deteriorated," said NTSB Capt. Dave Kirchgessner. Yet there were signs that the first officer was not coping well, among them that the aircraft was in a left crab and drifting, that control inputs were not sustained, and that there was no flare, he said.

"The captain had time to command a go-around," he said.

NTSB Member Debbie Hersman speculated that the captain hesitated to speak up because it was a check ride.

"It's possible," Kirchgessner agreed, but he stressed that the captain had opportunity to correct the first officer and had the option of taking the controls himself. Yes, he was to monitor the first officer's performance, but he also had a duty to ensure safe conduct of the flight, Kirchgessner said.

FedEx has established an Enhanced Oversight Program since the accident for pilots who need extra training. They are also rotating pilots between the MD-10 and the DC-10 simulators so that they better appreciate the differences between the two airplanes.

An Air Line Pilots Association (ALPA) representative said that the investigation did not recommend more information in the limitations section of the aircraft flight manual. "The pilots aren't told that a descent at 12 fps will break the airplane," he said. A descent of 10 fps equates to 600 feet per minute.

Of great concern to NTSB investigators was the preparation and training of FedEx pilots to operate the escape slides, and their interest in saving bags during the evacuation.

A non-revenue pilot attempted to deploy the slide from the forward left door (L1), but it blew away from the aircraft after inflation. Investigators found the manual inflation han-dle and the release handle on the floor

The non-revenue pilot said he'd pulled the manual inflation handle only.

The release handle was to be activated only if the evacuation slide was to be used as a raft in the event of a water landing.

Investigators found that the door used in training did not feature either the manual inflation handle nor the raft handle, a deficiency fixed by FedEx after the accident. The training is now more realistic in this respect.

With loss of the escape slide, the crewmembers and the deadheading pilots were forced to use escape ropes out the cockpit windows. As a consequence, the evacuation took considerably more time. Adding to this time was the fact that personal bags were shoved through the windows and hurled to the ground. Between the first and fourth occupant sliding down the ropes, some 13 bags were tossed overboard. The bags contained Christmas gifts and passports.