UK investigators have determined that a Pakistan International Airlines Boeing 777-200LR incorrectly assumed that ground-support equipment had been removed before commencing to taxi, striking the towbar which was still in front of the jet.

The tug and towbar had been disconnected from the aircraft (AP-BGZ), which was preparing to depart Birmingham on 22 August last year.

UK Air Accidents Investigation Branch analysis found that the 777 crew could see the tug parked to the left of the aircraft’s nose, and assumed the ground personnel had left.

But the ground personnel – unseen by the pilots – were positioning the towbar behind the tug, ready for removal.

PIA 777

Source: AAIB

As it moved forward the 777-200LR struck the towbar

The captain asked the first officer to request taxi clearance. Neither checked with air traffic control to remove doubt that all ground personnel were clear, and neither received a final all-clear hand signal.

Just 23s after the towbar was disconnected, the 777 began to move forwards. The inquiry says this interval would normally be around 2-3min.

“Shortly after starting to move, the aircraft struck the towbar and the crew stopped and applied the parking brake,” says the inquiry.

Neither of the ground personnel nor the tug was struck by the aircraft, although the towbar and the runway surface were damaged. The aircraft was inspected by a ground engineer and subsequently cleared to depart.