I think the psychiatric treatment rather than the actual nature of the offence caused alarm with CASA
But this should have sealed the deal from an aviation medical perspective;
The Civil Aviation Safety Authority knew Hempel, 60, to be a serial menace to public safety. His disciplinary record for flagrant breaches and dishonesty went back decades and became worse as he aged. He had put passengers and unsuspecting members of the public at risk with cavalier antics that appalled safety investigators - and cemented Hempel's status as a maverick with extraordinary skills but shocking judgment.
Doctors, medical specialists and CASA also knew that Hempel, who ran a Brisbane-based aviation company (motto: the sky's the limit) that flew politicians such as Nationals senator Barnaby Joyce, business chiefs and joy-riders, had severe epileptic-like seizures, believed to have begun after a brain injury from a hangar door accident in 2001. A loss of consciousness, rigidity and convulsing would occur; one ambulance officer who reported a 10-minute episode was so concerned about Hempel's status as a pilot that he kept notes on it for a decade.
These seizures would render Hempel an even more dangerous threat to the public. In one instance that became "common knowledge" shortly before his death, he was flying a Beechcraft Baron to Brisbane from the rural town of Dalby when, according to Nigel Arnot, an aircraft engineer, Hempel suddenly had "a seizure, a full fit with shaking". A friend "had to literally punch him out" to prevent inadvertent use of the controls and disaster.