Flight officer Rayan Gharazeddine looks out of a Royal Australian Air Force (RAAF) AP-3C Orion as it flies over the southern Indian Ocean during the search for missing Malaysian Airlines flight MH370 March 22, 2014. [Photo/Agencies]

CANBERRA -- A leading air crash expert has said missing Malaysia Airlines fight MH370 was likely to have been in controlled flight as it hit the water, giving life to the theory it was brought down by a rogue pilot or hijacker.

Air crash expert Larry Vance told Australia's Nine Network that there was no other way to explain why the flaperon, found off the coast of Madagascar, was "extended" meaning it would have been in controlled flight as it hit the water.

Vance said the only way to extend the flaperon, something which happens when a plane is attempting a landing, was for the pilot to engage a switch, something which is unlikely to have occurred during an sudden disaster.

"You cannot get the flaperon to extend any other way than if somebody extended it," Vance told the Nine Network's 60 Minutes program overnight.

"Somebody would have to select it (in the cockpit)."

Vance said, from photos released of the flaperon, there was evidence to show the aeroplane hit the water at a controlled speed, pointing to it being a "human engineered event."

"Somebody was flying the aeroplane into the water... There is no other alternate theory that you can follow of all the potentials that might have happened. There's no other theory that fits," he said.