Watchdog to probe fourth Sydney airport runway bungle

Safety at a major Australian airport is again in the spotlight, as a watchdog probes a fourth close shave between planes on a taxiway in less than a month.

A Qantas plane bound for Melbourne was forced to temporarily abandon takeoff preparations at Sydney Airport on Tuesday morning, after another Qantas flight was cleared to use the runway at the same time.

The larger Qantas Airbus A321 had been given permission to turn right onto the taxiway when the flight crew noticed the smaller Qantas plane, a Boeing 737, was travelling on the same path and in the opposite direction after touching down.

The Airbus was able to brake normally and there was no immediate risk of collision, the Australian Transport Safety Bureau said in a statement.

Air traffic controllers and flight crew will be interviewed by the bureau as part of an investigation into potential conflicting instructions that led to the bungle.

"If at any time the investigation identifies a critical safety issue, the ATSB will immediately inform relevant stakeholders," the bureau said.

The news comes after an incident on August 7 when a Virgin Australia jet was cleared to take off but swiftly cancelled as a Qantas plane already had permission to cross the runway.

A high-profile near-miss earlier in August forced a Jetstar pilot to brake to avoid a Qatar Airways plane as the Middle Eastern jet was towed across the tarmac, giving a flight attendant minor injuries.

Two Qantas planes were cleared to approach a runway at the same time during an episode on July 27.

A report detailing preliminary findings of Tuesday's incident is expected to be published in six to eight weeks.

Airservices Australia, the body in charge of traffic controllers, said it submits multiple reports to the ATSB each day.

"As with all reported occurrences, we will provide the ATSB with all relevant information and act on any findings arising from its investigation," a statement said

"The recent ground traffic incidents currently under investigation by the ATSB involve a range of circumstances, and each incident is being investigated on its individual facts."