On 10 December 2007 at about 2143 Eastern Daylight-saving Time a Cessna Aircraft Company 172N (C172) registered VH-WDA entered runway 17 at Essendon Airport, Vic. without an air traffic control clearance. At that time, a Piper Aircraft Corporation PA31, registered VH-BTD, was on final approach and had been cleared to land on runway 17. The pilot queried the landing clearance with the tower controller, who observed the C172's unauthorised entry onto the runway, or runway incursion, and sent the PA31 around in order to maintain separation between the two aircraft.

The pilot of the C172 was appropriately licensed, rated and current for the conduct of the private night visual flight rules (VFR) scenic flight and had notified the tower controller from the runway 17 run-up bays that he was 'ready'. In response, the controller instructed the pilot to 'taxi forward and hold short of runway 17'. That instruction was correctly read back by the pilot. Shortly after, the aircraft crossed the holding point and entered runway 17.

The C172 pilot had 311 hours total experience with 20 hours experience under the night VFR. The pilot was completing commercial pilot training and had been operating regularly at Essendon Airport over the previous 2 months. Most of those operations were reported to have been on runways 17 and 35. The pilot advised that the airport markings, signage and lighting were more than adequate for the planned flight.

The C172 pilot could not explain or rationalise why he had entered the runway when he had acknowledged the instruction to hold short of the runway. The investigation did not identify any operational factors that may have contributed to the development of the runway incursion.