A Boeing 777-200 was being prepared for its scheduled passenger flight from Birmingham (England) to Islamabad (Pakistan) on this day in 2019. 209 passengers had boarded the aircraft, which was crewed by 2 pilots and nine cabin crew.
The moment the aircraft runs over the towbar (Frame captured from airport CCTV recording, source AAIB)
After all the preparations were completed with passengers boarded clearance was obtained for pushback and engine start. After a normal pushback, the aircraft was stopped and the parking brake was set. The flight crew requested that the ground crew disconnect the ground equipment, and give a hand signal (Thumbs up and showing the removed Nose Wheel Steering Bypass pin) to the left of th aircraft when clear of the aircraft. The tug was disconnected, as was the towbar. The tug was positioned to the left of the aircraft's nose so that the towbar could be connected to the rear towing point of the tug, for removal from the taxiway.
The moment the aircraft started to move (Frame captured from airport CCTV recording, source AAIB)
From the flight deck, the crew observed the tug clear of the aircraft to the left and also saw the ground crew moving around. After a period during which the ground crew did not appear again and did not make contact, the flight crew assumed that he had left the aircraft. They attempted to gain the ground crew’s attention with gestures from the flight deck and via the intercom but were unable to do so. The aircraft commander, believing they were ready to taxi, asked the co-pilot to obtain taxi clearance. The flight crew did not ask ATC if they could assist in confirming that all personnel were gone from beneath the aircraft and did not receive the final clearing hand signal from the ground crew. The time interval from the towbar being disconnected from the aircraft to the aircraft starting to move was approximately 23 seconds. (During the investigation the handling agent commented that it would be usual for this period to be about two to three minutes.)
The aircraft approaches the towbar (Frame captured from airport CCTV recording, source AAIB)
Shortly after releasing the parking brake and starting to move forward, the aircraft struck the towbar. Noticing they had hit something the crew stopped the aircraft and applied the parking brake. None of the ground staff nor the tug were hit by the aircraft. No injuries were sustained by the ground staff. The towbar and the taxiway surface were damaged as a result of the collision. The aircraft was inspected by the airline's ground engineer and subsequently released to service, no damage was found. An investigation was launched by the Air Accident Investigation Branch (AAIB), in their report they gave the following analysis of the collision;
After a normal pushback, the ground crew were cleared to remove the ground equipment and intercom in the normal manner. After a while, the commander asked the co-pilot to obtain taxi clearance from ATC even though neither had seen a clearing hand signal from the ground crew. The flight crew tried to contact the ground crew but were unable to do so, and the tug remained in view to the left of the aircraft. They did not ask ATC to remove doubt about the position of the ground personnel and equipment and, as a result, the ground equipment remained in the path of the aircraft when it began to move and a collision resulted.
The AAIB investigation report, on which this blog is based, is available for the readers' reference by clicking on the .pdf file below: