Air France flight AF855 was the Lagos-Paris Charles de Gaulle flight , the final leg in the Paris – Lagos – Port Harcourt – Lagos – Paris rotation. The rotation began in Paris on January 9, and the Port Harcourt – Lagos flight was made on the day of the incident.
The crew landed at 21 h 00 on runway 18R in use on the day of the incident. The stopover lasted approximately 1 hour 30 minutes, during which the Captain wished to quickly prepare the flight for the next leg in order to be able to take a rest period of forty minutes in the cockpit.
The Captain was the pilot flying.
The push-back of the plane and engine start up was cleared by the controller at 22 h 50.
The pre-taxiing check-list was performed at 22 h 57.
Shortly thereafter, the controller cleared the crew, at its request, to taxi to runway 36L.
Note: The crew of flight AF855 requested to use runway 36L for takeoff because this allowed them to shorten the flight despite the longer taxiing time. The crews of 2 flights departing soon afterwards requested and used runway 18R. The weather conditions enabled use of either runway.
The Captain began the pre-takeoff briefing, and called out the associated speeds: V1 138 kt, VR 151 kt, and V2 157 kt
The controller then cleared them for takeoff.
Approximately 2 minutes later the Captain called out “Takeoff, V1 138“, the aircraft entered the runway and the crew began the takeoff roll without stopping the aircraft.
At 23 h 05 min 24, when N1 had stabilised at 62%, the recorded data show the TO/GA switches were pressed.
The Captain reported he performed this action.
At that moment, the recorded speed of the aircraft was 30 kt (CAS). The positions of the thrust levers and N1 indicator values remained stable.
At 23 h 05 min 27, the Captain stated “we have a problem…” and the TO/GA switches were recorded as being pressed a second time.
Two seconds later, the FDR shows that the auto-throttle was engaged using the MCP switches.
At the same time, the FDR shows that the autopilot engage button beside the pilot was pressed twice.
The autopilot engaged one second later.
Note: The Captain explained that when he noted the auto-throttle had not engaged, he temporarily removed his hand from the thrust levers in order to arm it via the MCP.
At 23 h 05 min 33, the Captain reported they had “no thrust”.
The copilot suggested “do it by hand” and the Captain replied that he wanted to know why.
During this exchange, the thrust levers were advanced to obtain N1 of 92.5%.
At 23 h 05 min 37, the copilot said “press the switches”. A speed of 80 knots was reached at around 23 h 05 min 42. At 23 h 05 min 45, the copilot reported that thrust was available. One second later, he announced “100 knots“.
The Captain replied that he had checked the speed and that “perhaps they had no auto-throttle”. The parameters show that the auto-throttle was armed but not active. At 23 h 05 min 58, the copilot announced “rotation”. The aircraft by then had travelled about 1,500 meters.
The Captain of Air France flight AF855 announced “abort takeoff”. The CAS recorded on the FDR was then 155 kt. The maximum airspeed of 164 kt was recorded 3 seconds later.
Note: The Captain explained that he made this decision after sensing a blockage in the elevator control when rotating.
The automatic braking system of the aircraft was activated and the aircraft stopped about 900 meters from the end of the runway at 23 h 06 min 30. Due to the presence of aircraft at the holding point of runway 18R, the crew made a U-turn in order to clear the runway.
At 23 h 07 min 54, the brake temperature warning was displayed on the EICAS when the brake temperature indicator for wheel number 3 exceeded the threshold value of 5 (on a scale from 0 to 9.9).
At 23 h 08 min 09, the autopilot disconnect alarm was recorded by the CVR. The FDR shows the autopilot was manually disconnected.
At 23 h 10 min 09, to prevent any risk of fire in the wheels, the crew requested the assistance of the airfield fire-fighting services. The fire-fighters from the service followed the aircraft along the taxiways a few minutes after the incident and then sprinkled the brakes with water when the crew arrived at the ramp. Tire 3 deflated around 23 h 12 min 40, while the aircraft was still on the taxiway, adjacent to its stand.
The associated brake temperature indicator reached 8.7.
Tires 1, 2, 6 and 4 deflated in turn less than 5 minutes later.
The aircraft arrived at its stand at 23 h 15 min 45.
This serious incident was due to:
- the Captain’s failure to arm the auto-throttle during cockpit preparation,
- the Captain’s decision to manipulate the auto-throttle switches on the MCP during a critical phase of the flight,
- the inadvertent engagement of the autopilot during this operation on the MCP,
- inadequate monitoring of the status of aircraft systems by the crew.
- The Captain’s decision to advance the cockpit preparation in order to leave time for a rest may have contributed to the failure to arm the auto-throttle.