On 6 December 2015, a Boeing 737-800 was being manoeuvred by tug from its departure gate at Singapore to the position where it was permitted to commence taxiing under its own power when the tug lost control of the aircraft, the tow bar broke and the two collided. The Investigation attributed the collision to the way the tug was used and concluded that the thrust during and following engine start was not a contributory factor. Some inconsistency was found between procedures for push back of loaded in-service aircraft promulgated by the airline, its ground handling contractor and the airport operator.