Australian crash investigators will look for any similarities between a New Year’s Eve seaplane tragedy that killed a British industry chief and a string of accidents involving the same aircraft type in Canada.
But a senior Australian Transport Safety Bureau executive warned against drawing parallels at this stage and said investigators in Australia had not previously identified a systemic issue with the de Havilland Beaver DHC-2 aircraft.
Some details about the last moments of the 1960s-vintage Canadian-built aircraft owned by Sydney Seaplanes emerged Tuesday with ATSB executive director Nat Nagy saying the seaplane took off at about 3pm for a return flight to Sydney.
“The aircraft took off in a north-easterly direction followed by a turn to the north-west and then a subsequent right-hand turn prior to impacting the water,’’ Nagy told reporters at the scene. “A short time after that, the aircraft sank and is currently on the bottom of the river in an inverted, slightly nose-down attitude.’’
The crash at Jerusalem Bay in the Hawkesbury River region north of Sydney took the life of top UK executive Richard Cousins, his extended family and experienced seaplane pilot Gareth Morgan.
With Cousins, the chief executive of Global food giant Compass Group, were his sons Edward and William as well as fiancé Emma Bowden and her 11-year-old daughter Heather. Cousins and Bowden, a magazine arts editor, were due to be married in July and the family had been eating at a waterfront restaurant.
Investigators hope to raise the plane by the end of the week and are calling for witnesses to come forward.
There has already been dramatic testimony from one witness, science teacher Will McGovern, about how his friends braved a mixture of water and fuel in a desperate attempt to save passengers from the quickly sinking plane.
“The whole time I was freaking out that this fuel was going to spark,’’ he told the ABC.
“This plane was moving fast, it was going down fast — they could have got sucked in.”
The men also tied a rope to the tail of the plane and tried to pull it to the shore with their boat.
“But it weighed a ton, the boat wasn’t moving it at all,’’ he said.
The full sequence of events will be pieced together by investigators as they collect evidence from the scene and conduct further investigations at the ATSB’s headquarters in Canberra.
Nagy said investigators would be looking at aircraft components as well as any recorded data from aircraft avionics and devices such as mobile phones, video cameras and iPads.
They would also look at aircraft maintenance records, the pilot’s background and experience and talk to operator Sydney Seaplanes.
“We will get the recorded data to see exactly what the aircraft was doing at the time – whether the aircraft was operating at full power, whether it was climbing or descending at the time, what sort of weight the aircraft was carrying at the time – and try to piece all of those together so we can fully reconstruct (the accident), ‘’ he said. “Once we’ve done that we’ll be able to put a picture together of what happened.
The Australian crash comes as issues about aerodynamic stalls in a number of DHC-2 accidents resurfaced in Canada earlier this year.
The Transportation Safety Board of Canada recommended in September that stall warning devices be made mandatory for commercially operated DHC-2s in a report on a 2015 fatal crash in Quebec.
The crash killed six people, including a British family of four, and brought the number of Canadian DHC-2 accidents involving stalls to 13 since 1998.
Whether the Australian plane stalled is unknown and Nagy said it was important at this stage not to draw any conclusions about systemic issues.
“We certainly haven’t identified anything previously that would indicate that this was systemic,’’ he said, noting the aircraft had been in operation for more than 50 years in other parts of the world in remote and challenging environments.
“I think it’s important not to draw parallels between what we are seeing here and those other incidents. But of course, we will look into all of those to see if there are any similarities.”
Canadian investigators found the experienced pilot of the Quebec plane, who was also a DHC-2 instructor, did not notice the impending stall during a steep turn approximately 110 feet above ground level.
It also found the absence of an angle of attack indicator and a stall warning device deprived the pilot of a last line of defense against loss of control of the aircraft.
At the time, Canadian regulations did not require stall warning systems on DHC-2, an aircraft that was originally certified in 1948.
“In the controlled conditions of certification, the stalling of the DHC-2 was described as gentle,’’ the TSB report said.
“However, as is the case for many other aircraft, a stall in a steep turn under power triggers an incipient spin with few or no signs of an impending stall, and the flight path changes from horizontal to vertical.
“In low-altitude flight, stalling followed by incipient spin, no matter how brief, prevents the pilot from regaining control of the aircraft before impact with the ground.”
The new recommendation came after the TSB expressed concern in a 2013 report that the DHC-2s aerodynamic buffeting did not provide pilots with adequate warning of an impending stall.
It pointed to the high frequency of accidents caused by an aerodynamic stall, as well as the catastrophic consequences of the accidents when they occurred at low altitude and during critical phases of flight.
As a result of that report, Transport Canada and manufacturer Viking Air recommended in 2014 that stall systems should be installed.
The TSB said the systems should be made mandatory after they were installed on just a handful of the 382 DHC-2s registered in Canada, 223 of which are used in commercial operations.