Decades-old light planes using piston engines instead of the safer, more reliable modern turbines are still being used to ferry health department patients around NSW despite a deadly crash involving one of the aircraft.
The father of the pilot who was killed in the Sydney crash in 2010 said he is concerned about some NSW patient transport operations and the performance of Australia's air safety watchdog .
Andrew Wilson, 27, and his nurse passenger Kathy Sheppard, 48, died when the patient transport plane he was flying developed engine problems leading him to shut down one engine and attempt to land on a road at Canley Vale in Sydney's south-west.
Mrs Sheppard was a former, much-respected Port Macquarie nurse and midwife who worked not only at Port Macquarie Base Hospital but its predecessor, the Hastings District Hospital.
In June 2010, the fully-fuelled aircraft, that was 26-years-old, slammed into a power pole and exploded during the landing attempt.
Wilson had managed to steer away from a nearby school.
Wilson's father Alan - who has waited years for official investigations to conclude including a 2015 coronial inquest before speaking - remains angry about the findings from the crash investigations and the state of ongoing operations.
One issue relates to the performance of Australia's Civil Aviation Safety Authority (CASA) which knew two years before the crash that Wilson and 25 other pilots were not qualified to be flying the planes because their training was deficient.
A summary of an investigation report into the crash by the Australian Transport Safety Authority (ATSB) found Wilson had made a series of incorrect decisions in piloting the plane, that had suffered engine trouble just minutes after taking off from Bankstown airport.
But in the full report there is confirmation that CASA knew two years before the crash that Wilson and the other pilots had not been endorsed to undertake the patient transfer flights in the aircraft.
And despite knowing that Wilson and 25 other pilots did not have the appropriate training, CASA then failed to ensure he and the other pilots received re-training, according to the ATSB report.
CASA had requested the operator ensure corrective training for the pilots but Wilson and some others never received the training and after the crash three more pilots were found to have not undergone appropriate training.
The ATSB report blamed the failing on the fact there were two companies involved in the operations that had separate air operator certificates and that different CASA inspectors were assigned to the surveillance of each company.
The ATSB said it was unlikely that Wilson's lack of training was a factor in the crash because of his lengthy flying experience in the aircraft.
However Alan Wilson disputes the position.
"Had things been done differently Andrew could be alive today," he said.
Mr Wilson is also concerned that piston-engine aircraft are still being used for passenger flights which are contracted to private companies by the NSW Government.
"A patient being transferred deserves to know that they are going to their destination safely and a piston-engine aircraft is not as safe as a turbine engine," he said.
A NSW Health spokeswoman confirmed that private operators undertaking patient transfer flights in the state were using piston-engine aircraft but said NSW Health required all patient transfer providers and their aircraft comply with CASA regulations.
A spokesman for CASA said there was no reason why piston-engine aircraft could not be used for patient transport work if they were "maintained and operated to the applicable safety standards".
He said it was important to note that the ATSB found it was unlikely deficiencies in the pilot's endorsement training contributed to the crash.
CASA had made significant changes to the way surveillance and safety checks of air operators were conducted, he said.
The spokesman said CASA had taken regulatory action in relation to the companies involved in the operation of Wilson's flight and cancelled their air operator certificates.