Two Australian pilots have been suspended for preparing to land a passenger plane without the correct landing gear, in what air safety investigators on Wednesday labelled a "serious incident".
The Qantas flight from Melbourne was forced to do a second lap above Sydney airport on
October 26 after a cockpit alarm went off as the Boeing 767 prepared to touch down, the Australian Transport Safety Bureau (ATSB) said.
"Passing 700 feet on approach into Sydney, the crew commenced a missed approach due to the aircraft being incorrectly configured for landing," the bureau said.
ATSB air safety spokesman Ian Sangston said the "too low gear" alert sounded because the landing gear had not been lowered, but said it was too early to speculate on the cause.
Qantas said flight safety was never at risk but it had stood the pilots down pending the bureau's inquiry into whether human error was to blame.
"This is an extremely rare event, but one we have taken seriously," the airline said in a statement.
"The flight crew knew all required procedures but there was a brief communication breakdown. They responded quickly to the situation... the cockpit alarm coincided with their actions."
The incident follows the revocation last week of the licences of two US pilots who overshot their destination by some 150 miles (240 kilometres) while distracted.