Incident Overview
On an unspecified date, an Air France cargo Boeing 747-200 parked at gate 111 at Montreal International (Mirabel) Airport, Quebec, was being prepared for a flight to Charles de Gaulle Airport, France. Ramp operations, conducted by Air Canada employees, were nearly complete when the co-pilot requested taxi clearance from the apron controller. Clearance was issued, and the captain began to taxi the aircraft. After moving about 85 feet, the right wing main landing gear struck a ground power unit (GPU) vehicle and pushed it approximately three feet before the captain stopped. No injuries occurred, but the aircraft sustained minor damage to two main wheel tires and a wheel-well door. The incident occurred in daylight.
Ground Handling Personnel and Procedures
The aircraft was being prepared by two ground handlers and one aircraft maintenance engineer, all Air Canada employees. One ground handler, the signalman, was positioned forward of the right wing at approximately the three o'clock position relative to the co-pilot. Both Air France and Air Canada procedures require the signalman to be forward of the aircraft and within view of the flight crew, but the open ramp concept at Mirabel prevented this due to vehicle traffic and jet blast hazards. The aircraft maintenance engineer was slightly forward of the signalman, observing engine start-up. Another ground handler, responsible for communications, was under the aircraft's nose with a headset connected to the intercom system; he told the pilots the aircraft was clear before engine start-up.
GPU and Intercom Issues
The GPU vehicle was situated on the right forward side of the aircraft. Company procedures required the GPU to be removed after disconnection, but local practice kept it near the aircraft for transporting wheel chocks and personnel. The communications ground handler disconnected his intercom before all staff and equipment were outside the security perimeter (25 feet around the aircraft), giving an "all clear" signal, but he had difficulty securing the intercom trap door. The flight crew was unaware of this difficulty. The aircraft maintenance engineer drove toward the nose to assist, but the crew did not see him due to cockpit duties. They believed the communications handler and signalman were the same person and that all vehicles were clear.
Taxi Clearance and Communication
When the co-pilot requested taxi clearance, the controller responded in French: "Air France 6443, circulez autour de la bâtisse par la droite pour la sortie Québec" (taxi around the building to the right for the Québec exit). The crew initially understood "bâtisse" as "Bât. 6" and searched charts before realizing the correct meaning. The accepted phraseology for the building is "cluster" or "îlot." The controller could not see the whole aircraft from the apron control tower due to the cluster building blocking his view; he is not responsible for confirming the area is clear—that responsibility lies with the flight crew.
Hand Signals and Conflict
The co-pilot recalled seeing the signalman with his closed right hand against his shoulder, interpreting it as a lax signal to proceed. The proper proceed signal is right arm extended straight out at shoulder height, left arm across chest pointing right. The signalman stated he kept his hands in the "stop" signal (both arms above head in an X pattern) and did not make eye contact. The signalman wore the same uniform as colleagues, with orange fluorescent gloves that were dirty and faded. He continued holding the stop signal while moving forward as the aircraft advanced, but the co-pilot did not look in his direction.
Sequence of Events
The co-pilot's taxi clearance request came 41 seconds after the captain told the intercom handler to disconnect and revert to hand signals. The aircraft began moving about 20 seconds after clearance and advanced for about 33 seconds before stopping. When the ground handler under the aircraft heard engines spool up, he attempted to drive the GPU away, but it stalled. He exited and ran to the left side; the captain saw someone by engine No. 1 and stopped.
Contributing Factors
The non-standard taxi clearance phraseology interrupted the crew's normal sequence and checklist, distracting them. The longer-than-normal elapsed time led the co-pilot to anticipate a proceed signal. The signalman's position at the limit of peripheral vision made him harder to notice. Conflicting statements about hand signals could not be resolved; the faded gloves may have reduced visibility. The GPU was not removed per procedures, and the communications handler incorrectly stated the aircraft was clear. No recent internal audit had been performed to verify compliance with procedures.
Causes and Contributing Factors
The investigation determined that after interpreting the signalman's hand signal as a proceed signal, the flight crew advanced the aircraft, which struck the GPU. Contributing was the ground handler's incorrect statement that the aircraft was clear when the GPU remained under the aircraft, a local practice not in accordance with published procedures of the air carrier or handling company.