Boeing MD-10-10F accident at Memphis, Tennessee, 18 Dec 2003

Accident narrative

On December 18, 2003, about 1226 central standard time, Federal Express Corporation (FedEx) flight 647, a Boeing MD-10-10F, crashed while landing at Memphis International Airport in Memphis, Tennessee. The right main landing gear collapsed after touchdown on runway 36R, and the airplane veered off the right side of the runway. A postcrash fire destroyed the right wing and portions of the right fuselage. Of the two flight crewmembers and five nonrevenue FedEx pilots on board, the first officer and one nonrevenue pilot received minor injuries during the evacuation.

### The flight

Flight 647 was a regularly scheduled cargo flight operating under instrument flight rules from Metropolitan Oakland International Airport in Oakland, California.

The captain, 59, had accumulated about 21,000 total flight hours, including 2,602 hours as an MD-11/-10 flight crewmember. He was a company check airman and was conducting a line check for the first officer during the trip.

The first officer, 44, was the flying pilot. She had about 15,000 total flight hours, with 1,918 hours in the MD-11/-10. The line check was required because the first officer had been the flying pilot during an altitude deviation the previous month.

### Sequence of events

The climb and cruise phases of the flight were routine. As the airplane approached Memphis, the captain and first officer discussed arrival procedures. About 1156, the captain stated, "I need to see a stable approach at a thousand feet. If for some reason we're not stable go around...all right?" The first officer agreed.

The captain obtained the current automatic terminal information service (ATIS) broadcast, which reported winds from 320 degrees at 16 knots with gusts to 22 knots, and noted that windshear advisories were in effect. Approach control initially advised the pilots to expect a landing on runway 36L, but later instructed them to expect runway 36R.

About 1221, the flight was cleared for a visual approach to runway 36R. The local controller cautioned the flight about wake turbulence from a heavy Airbus on a two-mile final and advised of a gain and loss of 10 knots on short final. The captain suggested adding four extra knots to their approach speed, and the first officer called for the landing gear down and the before landing checklist.

About 1223:52, the cockpit voice recorder (CVR) recorded a single central aural warning system (CAWS) "tailwind shear" alert. The captain stated, "okay, it's all right," and the first officer stated, "goodness." The pilots later reported that they decided to continue the approach because the alert was brief and they observed no airspeed excursions.

As the airplane descended through 1,000 feet above ground level (agl), the captain called, "visual. Stable." The first officer disconnected the autopilot about 1224:52. The CVR recorded altitude alerts down to 10 feet agl, followed by the sounds of touchdown about 1225:53.

About 14 seconds after touchdown, flight data recorder (FDR) data showed a lateral load factor of about 1.0 G as the right wing suddenly moved about 6 degrees lower. The CAWS "landing gear" alert began to sound. The airplane veered off the right side of the runway and came to a stop in the grass about 1226:30. A fire developed on the right side of the airplane.

### Emergency evacuation

After the airplane stopped, a nonrevenue FedEx pilot in the cabin opened the L1 emergency evacuation door. He stated that the slide/raft deployed but did not immediately inflate, so he pulled the manual inflation handle. The slide/raft inflated but separated from the doorsill and disappeared under the airplane. The R1 door was unusable due to the fire outside.

The occupants evacuated through the left and right cockpit windows using evacuation tapes. A bystander's videotape showed that the evacuation took about 152 seconds. The videotape also showed delays between evacuating crewmembers, during which several pieces of baggage were thrown from the airplane. Crewmembers later indicated they were offloading personal bags containing passports, clothing, and holiday presents while waiting to exit.

### What the investigation found

The investigation found that the airplane touched down on the left main landing gear first, about 564 feet from the approach end of the runway and 9 feet right of the runway centerline. The right main landing gear touched down about 49 feet further down the runway and 45 feet right of the centerline. Tire marks indicated the airplane was yawed about 5.4 degrees nose left of the runway heading at touchdown.

A performance study showed that the airplane's descent rate was 12.5 feet per second (fps) during the 20 seconds before touchdown. The left main landing gear touched down at about 12.5 fps, and the right main landing gear touched down at about 14.5 fps. The FDR pitch data showed no evidence of an increase in the airplane's pitch attitude (flare) before touchdown.

Boeing's landing energy analysis showed that the total energy dissipated to the right main landing gear was about 34 percent greater than the design reserve energy requirement. The Board concluded that the excessive vertical and lateral forces exceeded those the gear was designed to withstand, resulting in the fracture of the outer cylinder and the collapse of the right main landing gear.

A flight simulator study using the accident FDR data showed that the first officer began to apply left aileron and right rudder to align the airplane with the runway centerline about 160 feet agl. However, as the airplane descended below 100 feet, the aileron and rudder control inputs were neutralized and remained neutral until touchdown. The airplane drifted to the right with a left crab angle. The Board concluded that the first officer did not properly apply control wheel and rudder inputs to align the airplane or apply appropriate back pressure to arrest the descent rate. The Board also concluded that the captain failed to adequately monitor her performance and take corrective action when the airplane drifted.

Reviewing the first officer's training records, the Board noted a history of unsatisfactory checkrides at FedEx and at a previous employer. The Board noted that FedEx's recently implemented enhanced oversight program, which tracks pilots with training deficiencies to provide additional checks, would be beneficial to flight safety.

Regarding the evacuation, the Board found that the nonrevenue pilot who opened the L1 door mistakenly pulled both the manual inflation and slide/raft disengage handles. The Board noted that FedEx's emergency exit door/slide trainer in Memphis lacked a girt bar flap assembly, meaning it did not have manual inflation or disengage handles installed. Furthermore, FedEx's training did not require crewmembers to simulate pulling a manual inflation handle. The Board concluded that this inadequate hands-on training and the differences between the trainer and the actual airplane contributed to the unintentional release of the slide/raft. The Board also concluded that most of the pilots showed poor judgment and exposed themselves to unnecessary risk by delaying their evacuation to salvage personal items.

The investigation also reviewed the emergency response. The Memphis air traffic control tower ground controller delayed Rural/Metro Fire Department (RMFD) vehicles from crossing a runway for almost 2 minutes due to landing traffic. The Board concluded that the RMFD vehicles were unnecessarily delayed because the controller did not give them priority over nonemergency traffic. Additionally, the tower did not relay the number of people on board to the aircraft rescue and firefighting personnel.

Finally, the Board observed that the FDR aileron position data was not being updated at the rate required by Federal regulations, updating about once per 700 milliseconds instead of the required once per 500 milliseconds.

### Probable cause

The National Transportation Safety Board determined that the probable causes of the accident were "1) the first officer’s failure to properly apply crosswind landing techniques to align the airplane with the runway centerline and to properly arrest the airplane’s descent rate (flare) before the airplane touched down; and 2) the captain’s failure to adequately monitor the first officer’s performance and command or initiate corrective action during the final approach and landing."