A REX Regional Express Saab 340B, registration VH-ZRH performing flight ZL-2269 from Carnarvon,WA to Perth,WA (Australia), was taxiing for departure from runway 22 when the aircraft entered the runway to backtrack the runway.
A private Piper PA-31 was just in the takeoff roll from runway 22 and rejected takeoff due to the Saab entering the runway ahead of them.
The ATSB rated the occurrence an incident and opened a short investigation.
Both aircraft subsequently departed from Carnarvon's runway 22.
Carnarvon Airport does not feature a parallel taxiway to the runway, to reach the threshold runway 22 for departure the aircraft need to backtrack the runway entering the runway near the runway 22 end.