A Qantas jet was forced into a mayday call after running low on fuel while in a midair queue near Perth in Australia earlier this week.
According to the Sydney Morning Herald (SMH), the pilots of QF933 called the fuel mayday several hundred kilometres east of the city on Monday.
The air safety authorities are now investigating the issue.
The problem occurred when the Boeing 737 was put into holding pattern along with other flights due to ongoing delays at the airport.
According to the SMH, the plane arrived in Perth airspace with around 20 minutes of extra fuel, but were then told by air traffic control that the holding period had extended to 16 minutes.
The pilots were told they would have to declare a mayday in order to be prioritised for landing before four other planes.
The Australian Transport Safety Bureau (ATSB) said it was investigating the event.
"During descent, the crew declared an emergency due to the amount of fuel on board and proceeded to land at Perth. The aircraft landed with reserves intact," it said.
The aircraft, which had left Brisbane five hours earlier, eventually landed safely after the rare fuel mayday call.
The pilots had been in danger of landing without the legally required fuel reserves had they not been allowed to jump the queue.
Tony Lucas, Australian and International Pilots' Association president told the SMH that pilots around the world had to declare a fuel mayday if they expect to land without their minimum reserves.
"The aircraft landed with 40 minutes of fuel in the tank, which is well above the minimum requirements," Qantas chief pilot Dick Tobian said.
"Our pilots followed the correct procedures and there was no safety issue with the flight."
ATSB has said it will release a final report once its investigation has been completed.