The plane, a Lockheed Ventura, had taken off from Fairbairn just after lunch on December 7, 1943, when it was seen executing violent manoeuvres to the north of Canberra. Eyewitnesses later said the plane suddenly turned turtle and crashed into the ground upside down.

''No parachutes had been seen; the plane impacted the ground with a huge explosion,'' Canberra military aviation historian Bob Piper told Gang Gang.

In an article first published in The Canberra Times in October, 1996, Mr Piper said he had tracked down an RAAF crewman, Ernie Simons of Ballina, who had just missed out on taking the fatal flight.

''For some reason he [Ernie] had not felt comfortable with the new crew of Ventura A59-55 when due to go on a test flight with them,'' Mr Piper said.

''His doubts had arisen when he pointed out that the bomber had not been test flown since a major service.''

The pilot, Flying Officer Ron Sinclair, 22, had told Mr Simons: ''We can do that when we get in the air.''

Mr Piper said Mr Simons escaped death by a matter of minutes. When he arrived to go on the test flight, he found that the crew had already taxied out with another airman having volunteered to take his place.

By the time he returned to the Sergeants' mess 500 metres away, the news had come through that the plane had crashed.

All aboard had died instantly. In addition to Sinclair the crash killed flight sergeants W.K.H. Paterson (19), J.A. Paul (19), R.P. Tumulty (22) and A.H. Wright (21).

Mr Piper said Mr Simons acted as a pall bearer for four of the five victims at the joint funeral in the military section of the Canberra Cemetery.

Largely forgotten for many years, the crash became the subject of renewed interest in the mid-1990s when the site was rediscovered. Some debris still remained.

A memorial to the dead airmen was unveiled at the Gundaroo Public School on April 24, 1997. It had been commissioned by the Gunning RSL and students from the school took part in the memorial service.

The site of the crash remains in confidence as Mr Piper and others don't want it to be pillaged by souvenir hunters and curiosity seekers who may be tempted to remove some of the remaining material.

Relatively few traces were left at the scene after the RAAF recovered all the reusable elements in 1943.

The Ventura was the larger sibling of the Lockheed Hudson and, like that plane, served in a ground attack role. Although heavily armed with six machine guns and the ability to carry almost 1.5 tonnes of bombs, it was considered inferior to other designs such as the B-25 Mitchell and the De Havilland Mosquito.

There is only one Ventura left in Australia, a plane that is being restored by the Queensland Air Museum near Caloundra on the Sunshine Coast.