Two Qantas pilots have been suspended after a Boeing 767 came within 700ft of landing at Sydney airport before they realised the wheels had not been lowered.
The airline has launched an investigation into the incident and the pilots are due to be interviewed by air safety investigators on Friday.
The flight from Melbourne was forced to do a second lap above the airport on October 26 after a cockpit alarm went off as the Boeing prepared to touch down, the Australian Transport Safety Bureau said.
Investigators are understood to be looking at possible human error and a communication breakdown between the first officer and captain about who was lowering the undercarriage, according to The Australian.
It quotes a former Boeing 767 pilot as saying that a crew on an instrument approach would normally start lowering the undercarriage when the plane was between 2,000ft and 1,500ft from the ground in order to ensure that the aircraft was stable and configured to land by the time it was down to 1,000ft.
In visual conditions, the former pilot said, the aircraft needed to be stable by 500ft, but lowering the gear at 700ft or even at 1,000ft was still far too late.
According to the International Air Transport Association, problems with landing gear resulted in 15 per cent of airline 'hull-loss' accidents last year.
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 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's 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.
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.
Sangston said the ATSB was also investigating an incident in which the autopilot briefly disconnected on board a Jetstar flight between Japan and the Gold Coast as it passed through stormy conditions on October 29.
'My understanding is that there was some sort of problem with the information being provided to the pilots,' Sangston said.
Qantas' budget offshoot Jetstar said early indications were that the Airbus A330's airspeed sensing system was momentarily impaired, and several parts had been replaced on the aircraft before it was allowed to resume flying.
The error messages were similar to those reported from an Air France Airbus A330 jet which mysteriously plunged into the Atlantic in May, taking the lives of all 228 people on board.
But Sangston said the ATSB was yet to examine the black box data from the craft or interview the crew and it was 'only conjecture' to draw parallels.