The Australian Transport Safety Bureau (ATSB) was called in after the twin-engine aircraft slid off the runway and into grassland at the town's airport, on the afternoon of August 20.

The official probe is continuing, but an ATSB report has revealed there were two large holes in the tarmac on the runway the plane was travelling down.

A statement from the aircraft's pilot said he noticed something on the runway in the distance at the time, but thought he was looking at patches on the tarmac.

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"As the aircraft accelerated, it became apparent that there were two holes excavated from the runway pavement," the report reads.

The ATSB said the pilot - who was taking of en route to the Gold Coast - tried to avoid the section but couldn't.

The small plane slid off the runway and into grassland, and damaged its undercarriage, propeller and wheels.

The pilot had a lucky escape, and no one was injured in the emergency.

ATSB investigators found the airport was closed on the day in question for pavement works, after the council submitted a notice.

A white cross signifying the runway was shut was put in a spot where it would be visible to aircraft coming in for landing, but the ATSB confirmed the pilot had said he hadn't seen any visual cues to show works were in progress.

The ATSB is expected to release its findings in a final report next year.