The pilot lost control of the plane shortly after taking off from the Tyagarah air strip near Byron Bay earlier on Tuesday morning, a witness told ABC radio.

"He almost went upside down. I thought he was going to do some sort of loop, it was just too close to the ground that's how steep the bank was," he said.

The pilot, who was the only person on board, was found conscious and breathing when emergency services arrived at the scene.

Police Inspector Brendon Cullen said the man was rushed to Gold Coast University Hospital in a critical condition where he later died from his injuries.

While the man is yet to be formally identified, he is believed to have been from the Gold Coast.

Police from Tweed Byron Local Area Command will be working with investigators from Recreational Aviation Australia and the NSW Police aviation support branch to determine the cause of the crash.

It is the second serious incident to occur at the airfield this year after two skydivers died when they crashed to the ground after their parachutes became tangled midair.