The postcard was one of 1331 mail items flown from Mount Gambier to Melbourne by pioneer Australian aviator Basil Watson in February 1917.

Watson took off in his home-built biplane on February 15, stopping in Casterton, Hamilton, Camperdown and Warrnambool before arriving in Melbourne 12 days later.

The postcard, stamped in Warrnambool, was one of 150 pieces of Australian aviation memorabilia featured in Nelson Eustis' collection.

The Adelaide collector died in 2002 and his memorabilia was sold by Melbourne's Charles Leski Auctions for the Australian record price of almost $400,000.

Managing director of the auction house Charles Leski said pieces of Australia's aviation history were growing in popularity among collectors.

"There was a lot of interest in this auction, there are certainly hundreds of people collecting this type of thing," he said.

"Pilots were considered daredevils and heroes largely because the distance they travelled was so great.

"We take it for granted today that we can just jump on a plane and while it seems like a long time ago, it really is little more than one lifetime that it was a very dangerous thing to do."

Mr Leski said eight postcards flown by Watson in January and February 1917 were bought by individual collectors from New South Wales, Victoria, South Australia and England.

The postcards hold special significance because they were delivered on one of the last journeys made by Watson before he died in a plane crash at Point Cook on March 28, 1917. The Warrnambool postcard was sold for $525.

A Casterton postcard from the same flight was also sold for $525 while one from Hamilton fetched $550. The big seller of the bunch was a Camperdown to Melbourne postcard, which made $2000.

The special issue postcards featured a photograph of Watson on the back with space for correspondence. Postage was one penny.