What happened
On April 10, 2011, an Air Canada Boeing 777-333ER, registration C-FIVM, was undergoing a pushback maneuver at Paris Charles de Gaulle Airport. Due to the presence of another aircraft on taxiway P, the ground crew performed a short pushback from stand A4, which left the aircraft misaligned with the taxiway.
To correct the alignment, the ground crew initiated a "push-pull" maneuver, involving reversing the tug to pull the aircraft into position. During this process, the aircraft's number 2 engine had already been started. As the tug moved in reverse, the aircraft began to accelerate due to the combined effects of the engine's thrust and the downward slope of the taxiway. The aircraft moved toward the tug, causing the towbar to pivot and wedge under the nose gear tire. The towbar snapped, causing the aircraft to lose connection with the tug and collide with the vehicle. The impact resulted in damage to the aircraft's nose gear, a split tire on the tug, and the destruction of the towbar.
The investigation
The investigation examined the sequence of events using flight data from the FDR, ground radar, and testimonies from the flight crew and ground personnel. The investigation also reviewed the operational procedures of Air Canada, Air France, and the ground handling agent, AGS.
Investigators found that the aircraft's number 2 engine was running at ground idle during the pull phase. While Air Canada's internal documentation prohibited pulling an aircraft with an engine running, this specific safety rule had not been effectively communicated to the ground personnel performing the maneuver. Furthermore, the ground assistant did not notify the flight crew that a pull maneuver was being attempted, nor did they instruct the crew to shut down the engine.
Findings
- The primary cause was the decision to perform a pull maneuver while an engine was running.
- The aircraft accelerated toward the tug due to the thrust from the running engine and the 1.46% downgrade of the taxiway.
- There was a lack of coordination between the ground assistant and the flight crew regarding the transition from a push to a pull maneuver.
- A failure in the communication of safety procedures meant that the ground crew was unaware of the operator's prohibition against pulling aircraft with engines operational.
- The ground assistant failed to instruct the flight crew to stop the engine or apply brakes during the critical phase of the maneuver.