Vehicle / B738, Brisbane Australia, 2006
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On 21 April 2006, the crew of a Boeing 737-800 (VH-VXS) being operated on a scheduled passenger flight from Brisbane to Mount Isa in normal ground visibility and daylight commenced take off in accordance with their issued clearance and then observed a vehicle crossing the runway ahead. Having assessed that it would be clear by the time their aircraft reached the crossing position, they continued and completed the take off with no actual conflict resulting.
An Investigation was carried out by the Australian Transport Safety Bureau (ATSB) into the incident which was classified as an ‘Operational non compliance’. It was established that the 737 had entered runway 01 for take off from taxiway A7 (see the annotated diagram below). A vehicle towing an out of service 737 (Tug 41) was behind the departing 737 at A7. Another vehicle not towing an aircraft, Tug 92, was at the H4 holding point and both vehicles were waiting for clearances to cross the runway which, in accordance with local practice, would be given by the GND controller on the GND frequency. Seven seconds after the TWR controller had issued a take off clearance to the departing 737, the GND controller cleared the Tug 92 to cross the runway (from right to left as viewed by the crew of the departing aircraft) and it began to move.
Shortly afterwards, the 737 began its take off roll with the First Officer as PF. The PF stated that he had first seen ‘something on the runway’ when the aircraft was accelerating through about 50 knots and the Pilot Flying (PF) and Pilot Monitoring (PM) was ‘head down’ completing the setting of take off thrust. The PM had looked up and had assessed that the vehicle would be clear by the time they reached its position “and at about 80 knots had called ‘continue’ (with) the aircraft about 1200 metres from the vehicle”. Subsequently the vehicle cleared as expected and the aircraft “was airborne prior to reaching (the intersection involved)”. It was noted that the distance between the A7 and H4 intersections was 1418 metres.
It was reported to the Investigation by the ANSP that the GND controller had stated that “at the time of the incident he had ‘formed a mindset or belief’ that the required coordination for both tugs had been completed”, when in fact only the coordination for Tug 41 had been passed to the (TWR controller). The (GND controller) had also indicated at that time that “he had wrongly believed that he had a clearance from the (TWR controller) for both Tug 92 and Tug 41 to cross the runway”. The Investigation did not indentify any specific distraction which might have affected the performance of the GND controller at the time of the incident and the ANSP advised that there was no evidence that fatigue was a factor.