During pushback the shear pins on the towbar fractured. The ground crew heard a noise and checked the towbar, but did not discover the broken shear pins, so the pushback continued and the left engine was started.
As the aircraft was subsequently pulled forward, it gained momentum and began to deviate to the right of the direction in which the tug was moving. The tug driver assumed the towbar had separated and tried to move away but a retaining pin, that was subsequently found intact, had prevented tow bar separation, and the aircraft was pulled towards the tug. Before the aircraft could be halted by the pilot the tug collided with the lower left fuselage. The engines were shut down and the passengers disembarked from the rear of the aircraft without injury.
Investigations by the ground handling company, the airport operator and the aircraft operator highlighted maintenance and training issues and a range of safety actions have been taken.
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Published 14 December 2017