The pilot of a Navajo Chieftain was intending to take off on runway 34L from the intersection of taxiway B 10 at Sydney, at night. A Saab 340 had been cleared to depart prior to the Chieftain. Another Saab 340 was on final approach to land on the same runway.
Once the departing Saab had been cleared to take off, the arriving Saab was cleared to land. The pilot of the Chieftain was then given a conditional clearance to line up on the runway, behind the landing aircraft. In the same transmission, the pilot was also given instructions regarding the direction of turn and heading to adopt after becoming airborne.
The pilot of the Chieftain heard the line-up clearance and the after take-off instructions, but did not hear the condition that he should line up behind the landing aircraft. The pilot read back the instructions he had heard to the controller, however, the controller did not notice that the condition on the line-up clearance was not read back to him. The Chieftain then commenced to line up on the runway. The pilot saw an aircraft on final approach to runway 34L as he lined up, and was expecting an immediate take-off clearance from the controller. The crew of the Saab noticed an aircraft on the runway and, after contacting the tower, commenced a go-around from a height of approximately 35 ft, overflying the stationary Chieftain at a height of about 150 ft.
The Civil Aviation Safety Authority recommends in Aeronautical Circular H12/95, that if an aeroplane is fitted with strobe lighting it should be turned on before entering an active runway. The pilot of the Chieftain believed that he had done so. However, neither the controller nor other flight crew recalled seeing the strobe lights of the Chieftain.
Although the conditional take-off instruction was correctly issued by the controller, the read-back of the clearance by the pilot was incomplete, which was not detected by the controller. When the Chieftain then entered the active runway it is possible that the pilot did not switch on the strobe lights, reducing the likelihood of the crew of the approaching Saab, and the controller, seeing the aircraft on the runway. The subsequent go-around of the Saab was initiated when the crew saw the aircraft on the runway. For undetermined reasons the controller did not notice by normal visual scan, or by reference to the surface movement radar, that the Chieftain had already entered the runway, contrary to its assigned clearance.