Carbon monoxide poisoning behind seaplane crash

Sydney Seaplanes spokesman says company responsible for the aircraft’s maintenance ‘should accept responsibility for accident’.

An ATSB investigation found Sydney Seaplanes pilot Gareth Morgan was incapacitated by carbon monoxide gas when a DHC-2 Beaver crashed into Jerusalem Bay on the Hawkesbury on New Year’s Eve, 2017. Picture: Facebook

The investigation into the deadly Sydney Seaplanes crash on December 31, 2017, was almost two-years-old before carbon monoxide poisoning was considered as a possible cause.

Despite pilot incapacitation being the most obvious explanation for the crash into Jerusalem Bay on the Hawkesbury River, toxicology tests on the six victims had not covered carbon monoxide levels.

Releasing the Australian Transport Safety Bureau’s final report on the DHC-2 Beaver crash, chief commissioner Greg Hood said they were of the understanding carbon monoxide exposure was tested in initial toxicology examinations.

But in late 2019, the ATSB’s aviation medical specialist recommended this be confirmed, Mr Hood noted.

“Subsequent toxicological testing indicated that the pilot and all passengers had elevated levels of carboxyhaemoglobin,” he said.

“The pilot would have almost certainly experienced effects such as confusion, visual disturbance and disorientation. Consequently, the investigation found that it was likely that this significantly degraded the pilot’s ability to safely operate the aircraft.”

As a result of the findings, it was then discovered that non-compliant bolts installed in the firewall between the Beaver’s engine bay and the cabin, had deteriorated and allowed carbon monoxide gas to enter the cabin.

Mr Hood said the investigation highlighted the importance of “conducting a thorough inspection of piston-engine exhaust systems and the timely repair or replacement of deteriorated components”.

“In combination with maintaining the integrity of the firewall, this decreases the possibility of CO entering the cabin,” he said.

A Sydney Seaplanes spokesman said the company responsible for the aircraft’s maintenance “should acknowledge and accept responsibility for the accident”.

“All commercial airlines in Australia are required to use a Civil Aviation Safety Authority-certified maintenance organisation and we placed our trust in Airag Aviation Services which, until this accident, was Australia’s most respected and experienced DHC-2 Beaver maintenance company,” he said.

“This report confirms that Airag failed in its most basic and important responsibilities, which were to properly maintain our aircraft in accordance with the required standards to protect the safety of our passengers and crew.”

The ATSB made several safety recommendations as a result of the crash including the installation of on-board recording devices on smaller passenger carrying aircraft.

Mr Hood said the ATSB was making a formal recommendation to the International Civil Aviation Organisation (ICAO) and CASA, to mandate lightweight devices on commercial passenger aircraft.

“Recording devices have long been recognised as an invaluable tool for investigators in identifying the factors behind an accident, and their contribution to aviation safety is irrefutable,” said Mr Hood.

“There are a large number of commercial passenger-carrying operations conducted in aircraft that do not require the fitment of flight recorders. So there remains the potential for unresolved investigations into accidents involving smaller passenger carrying aircraft, which poses a significant limitation to bringing about safety improvements in this sector of aviation.”

The ATSB also highlighted the use of attention-attracting CO detectors, to give pilots the best chance of detecting CO exposure before it affected their ability to control the aircraft.

The victims of the crash included experienced pilot Gareth Morgan, British millionaire Richard Cousins and his sons William and Edward, Mr Cousins’ fiance Emma Snowden and her 11-year-old daughter Heather.

Airag was contacted for comment.