Fourth Sydney Airport safety incident in three weeks under investigation

The Australian Transport Safety Bureau is investigating a fourth safety incident at Sydney Airport in almost as many weeks.

A Qantas flight to Melbourne stopped after it was given permission to turn onto a taxiway where another plane was travelling to let them pass.

Airservices Australia says it will continue to review operational events and take any required to maintain safe operations.

A fourth incident involving aircraft on the ground at Sydney Airport in just over three weeks is being investigated.

Airservices Australia, the government-owned organisation responsible for air traffic management, said it reported the "potential traffic conflict" between two Qantas planes to safety authorities on Tuesday.

The Australian Transport Safety Bureau (ATSB) said that just after 8am, Qantas flight QF589 had been heading west along taxiway Lima after landing from the Gold Coast.

At the same time, Qantas flight QF405 to Melbourne had been given permission to turn onto that taxiway.

The ATSB said that when the crew of the Melbourne-bound flight noticed the other plane, they stopped and allowed it to pass ahead of them.

"As such the ATSB has classified this as a safety "incident", rather than a "serious incident", but has elected to conduct an investigation to understand the potential conflicting instructions to the flight crews."

Qantas said its aircraft had been cleared to proceed following instructions from air traffic control.

It is the fourth time conflicting instructions have been relayed to planes on Sydney Airport's tarmac in just over three weeks.

On July 27, a Qantas 737 was cleared to cross the main runway, where a QantasLink flight had been landing.

A Jetstar cabin crew member was injured two weeks later, when the plane they were in was forced to slam on its brakes to avoid hitting a Boeing 777 under tow.

Later that same day, a Virgin flight was cleared to take-off before that permission was swiftly rescinded because a Qantas plane had been cleared to cross the same runway more than 1,200 metres in front.