The latest postponement marks the fourth full cancellation after action was also wiped out on days one, four and eight.

"By mid morning there had been enough rain on the runways that it was clearly not going to be possible to grid 110-plus gliders on what had been grass and dust, but was now grass and mud," read a post on the tournament's blog.

"So the Open and 18 metres classes were cancelled.

"Gridding was quickly organised for the 15m Class on the 26 bitumen runway, which was surrounded by muddy grass.

Some members of the 15m class managed to get into the air, only for the task to be abandoned moments after leaving gliders frustrated.

Success for Poland's Sebastian Kawa yesterday saw him move on to a score of 4,417 points, 33 behind current leader Mac Ichikawa of Japan in the 15m class.

Lucasz Grabowski, also of Poland, was fourth in yesterday's race and remains third on the standings.

Frenchman Killian Walbrou holds top spot in the 18-metre class with a score of 5,661.

Just 73 points separate the top three, led by Walbrou, who has 5,661.

Germany's Matthias Sturm is second on 5,593, while Great Britain’s Mike Young follows on 5,588.

Britain’s Russell Cheetham retained first position on the open class leaderboard despite only managing 11^th place yesterday.

Cheetham has 5,786, with team-mate Andrew Davis, who was fourth yesterday, occupying second on 5,764.

Defending champion Michael Sommer of Germany is hot on the heels of the British duo in third.

Competition in the 15m and 18m classes on day two was also abandoned following a mid-air collision involving Australia's Stephen O'Donnell and Germany's Michael Eisele.

The accident happened over Yerong Creek en-route to Narromine.

The two pilots, both of whom were forced to bail out of their aircraft and parachute to safety, were taken by helicopter to Canberra hospital, where they were treated for minor injuries.