Incident Details
During a pushback operation at a gate, a ground support employee attempted alone to connect a towbar to a paymover. The paymover reportedly moved uncommanded rearward and collided with other ground equipment. The engine was shut down, and a ground support supervisor boarded the paymover to attempt the pushback again.
The supervisor stated that after starting the engine and releasing the parking brake, the paymover moved uncommanded forward. Attempts to stop it were unsuccessful. The paymover collided with the towbar, then with a ground power unit (GPU), which was pushed into the airplane fuselage.
Post-Accident Testing
After the accident, the normal brake system—which had not been repaired—was operationally tested, and no defects were noted. An operational test of the neutral safety switch could not duplicate the malfunction. Similar discrepancies regarding uncommanded movement of the paymover had been reported.
Additional Information
The investigation did not identify a probable cause. The source did not specify the aircraft type, registration, operator, date, location, occupants, injuries, or damage extent.