What happened
On the night of November 5, 2000, a Cameroon Airlines Boeing 747-200, registration TJ-CAB, was completing a scheduled flight from Douala to Paris Charles de Gaulle. The flight, operating as UYC070, arrived with significant delays. During the landing roll on runway 09L, the aircraft began to deviate rapidly to the right of the runway centerline.
As the aircraft traveled approximately 1,700 meters down the runway, it exited the paved surface between taxiway connectors Z6 and Z7. The aircraft struck a rainwater collection structure, which caused the nose gear to be torn from the airframe, resulting in heavy damage to the electronics bay. The aircraft eventually came to a halt on the concrete structure of the collector. There were no fatalities among the 187 passengers and 3 crew members on board, though the aircraft was a total loss.
The investigation
The BEA investigation focused on the deceleration process and the configuration of the engines during the landing roll. Investigators examined the thrust reverser settings, finding that the reversers on the two left engines were in the retracted position, while the reversers on the two right engines were deployed.
Technical examinations of the engine number one thrust reverser and its electrical circuits showed no mechanical or electrical malfunctions prior to the event. The investigation also looked into the cockpit environment, noting that two passengers were occupying the jumpseats in the cockpit during the approach and landing phases. Furthermore, the investigation reviewed the crew's coordination and the manual intervention of the flight engineer, who attempted to manually deploy the speed brakes after the automatic braking system disengaged.
Findings
- The primary cause of the accident was the incomplete reduction of thrust on the number one engine at the start of the deceleration phase.
- This failure to reduce power led to the deactivation of the automatic braking systems and prevented the deployment of the number one thrust reverser.
- An inadvertent application of high positive thrust on the number one engine created a significant thrust asymmetry, causing the aircraft to veer off the runway.
- A lack of crew coordination and mutual monitoring, potentially exacerbated by the presence of non-crew members (passengers) in the cockpit, contributed to the situation.