The main part of the wreckage of a sea plane that fatally crashed into Perth’s Swan River on Australia Day has been retrieved and sent off for examination.

Aviation experts have been at a loss to explain what caused the crash, which claimed the lives of the pilot, mining executive Peter Lynch, and his colleague and partner Endah Cakrawati.

The Australian Transport and Safety Bureau launched an investigation, which is expected to take up to 12 months to complete.

The air show was part of the Skyshow Australia Day festivities on the Perth foreshore, and was to be followed by the annual fireworks display, which was cancelled in the wake of the crash.

The Aero Club of WA said it was the first accident in the history of the air show, which was choreographed down to the last second.

“The aerial displays and so on have always been part of Skyshow… I hope they would continue,” Mr Barnett said.

“Obviously something went terribly wrong, there will be a full inquiry and we’ll get the answer to that.”

The plane’s tail was removed from the river on Friday.