A passenger plane came close to disaster after one of its propellers fell off as it approached Sydney's main airport.
The 16 passengers and three crew on the Regional Express flight ZL768 narrowly avoided a catastrophe when the propeller almost hit the wing and tail after it sheared off.
"They were a hair's breadth away from a disaster. I don't know how the hell it didn't damage the aircraft as it went past," said Paul Cousin, the president of the Australian Licensed Aircraft Engineers Association.
The only sign that something was up with the twin-engine craft was when the pilots felt a vibration about 12 miles from Sydney Airport.
As they prepared to shut down the right-hand engine as a precaution, they saw the propeller disappear over the plane's wing from the cockpit window.
They made a PAN emergency call to air traffic control, which is one step down from a full-scale mayday alert, and ground crews prepared for a possible crash landing.
But the pilots of the Saab 340, which had set out from Albury, around 300 miles from Sydney, made a successful emergency landing by gliding the plane in on Friday.
The crew said the propeller assembly had "dislodged", according to Civil Aviation Safety Authority spokesman Peter Gibson, who said three investigators were looking into the "very, very unusual" incident.
"We don't have any idea at this stage why the propeller should separate from the engine," he said.
It is reported the propeller detached at 6,000ft, with the flight deck describing it as "just shed[ding] off" on air traffic logs.
Photographs of the plane on the ground show the right propeller had fallen off entirely, while early inspections suggest that it broke away from the shaft in the engine.
Twin-engine planes can land safely on one propeller and, while no one was injured, the passengers were offered counselling after landing.
People living in southwestern parts of the city have been told to inform police if they find the missing part, which will form a key part of an investigation.