The crew of a SAAB, conducting a scheduled passenger service from Griffith to Sydney, broadcast that they were taxiing to depart from runway 06. The pilot of a Cherokee advised that he was on downwind for runway 36. The crew acknowledged this transmission and then established the position and intentions of the pilot of a Dromader who was on an extended downwind leg for a low-level approach to runway 06. The crew of the SAAB then advised that they were entering and backtracking on runway 06. Approximately 90 seconds later, when the crew advised they were rolling on runway 06, the pilot of the Cherokee responded that he was on late finals to runway 36. The crew continued their take-off and overflew the landing Cherokee by a reported 400 feet.
Each aircraft was in radio communication on the Griffith common traffic advisory frequency of 126.7 MHz.
The crew of the SAAB later reported that they had not heard the pilot of the Cherokee respond to their taxiing broadcast. Their attention had been directed toward the pilot of the Dromader who had adjusted his approach to assist their departure. They had not seen the Cherokee and consequently it was not until the pilot reported on late finals to runway 36 that they realised there was a traffic conflict. The crew reported that at this time the SAAB had accelerated to a speed such that rejecting the take-off was potentially more hazardous than continuing.
The higher terrain to the south of the aerodrome may have made the Cherokee more difficult to detect against the background. Additionally, a line of trees to the south of runway 06 obscured the final approach path to runway 36 from the view of pilots at the 06 threshold.
The reason why the crew of the SAAB did not recall hearing the response of the Cherokee pilot to their taxiing report was not determined. However, it is likely that the decision to expedite their departure ahead of the arriving Dromader created a self-imposed high workload that led to a loss of awareness of the Cherokee.