The world's biggest plane, due to land in Perth on Sunday, was loaded with its cargo, a 117-tonne generator purchased by a WA resources company, on Wednesday and is now making its way to WA from Prague.

Up to 50,000 aviation enthusiasts are expected to pack vantage points at Perth Airport to witness the arrival of the Ukraine-built Antonov An-225 Mriya at 10am.

The last time a crowd that size flocked to the airport was in the 1980s when the Concorde supersonic airliner landed.

Aviation Association of WA president David Eyre said it may be the only time the six engine plane, which once transported a Russian space shuttle on its roof, travels to Australia.