The Australian Transport and Safety Bureau, ATSB, investigation into a fatal helicopter crash on Mount Disappointment in 2022 has highlighted the importance of proper pilot training and appropriate procedures when flying into inclement weather.
Two Airbus EC130 helicopters, operated by Microflite, departed a helipad at Melbourne’s Batman Park bound for Ulupna in Victoria’s north on the morning of March 31, 2022.
The route was diverted to travel over Mt Disappointment after a Melbourne Airport forecast had indicated to the pilots that weather conditions would be unsuitable for flight below cloud on the original route through Kilmore Gap.
Both pilots were operating under the visual flight rules, VFR, which apply when a pilot can physically see features outside the aircraft, such as the ground, to determine where the aircraft is going.
Despite operating under the VFR, the pilots had planned for and set off on a route for which instrument meteorological conditions, IMC, were present – weather conditions requiring pilots to fly primarily by reference to the aircraft’s flight instruments.
Both helicopters continued the flight as conditions deteriorated until the leading helicopter made an urgent call to conduct a U-turn, which when performed by the trailing helicopter caused it to rapidly descend while in cloud.
“During the attempted U-turn without visual cues the second helicopter developed a high rate of descent, resulting in the collision with terrain,” ATSB chief commissioner Angus Mitchell said.
“Unfortunately, the pilot had no instrument flying experience, and the helicopter was not equipped with any form of artificial stabilisation, albeit neither of which are required for VFR flying.”
The helicopter collided with the ground, during which it was destroyed and all five occupants died.
The Review reported in April 2022 that the crash was ‘one of the worst aviation crashes in Victoria’s history’, with more than 60 people from various emergency and environment services in attendance to both assist in recovery efforts and aid investigators in accessing the crash site.
Shortcomings
Mr Mitchell said while not required by regulations, the helicopter operator had not incorporated several available risk controls for its VFR pilots to mitigate inadvertent entry into IMC – a situation where a pilot loses sight of the ground due to deteriorating weather.
“These risk controls may have included inadvertent IMC recovery training and basic instrument flying competency checks during operator proficiency checks,” he said.
It was found the operator had also not introduced an inadvertent IMC recovery procedure for its air transport operations, nor had it included a pre-flight risk assessment to trigger measures to deal with the marginal weather conditions previously identified.
The report noted the operator had identified poor weather conditions as a risk, however its management of the risk was limited to mandated regulatory requirements and did not consider ways to assist the pilot in recovering from an inadvertent IMC event.
The Civil Aviation Safety Regulations for rotorcraft air transport (Part 133), developed by the Civil Aviation Safety Authority, CASA, only require the risk of an inadvertent IMC event to be managed through avoidance.
In conducting the U-turn, the leading helicopter had acted to avoid a reported ‘wall of cloud’ at Mt Disappointment and had broadcast to the trailing helicopter its intention to turn around before performing the manoeuvre.
According to the report, the trailing pilot was initially confused as to why the leading helicopter wanted to turn around and may have thought the conditions were suitable to continue.
“While avoidance of inadvertent IMC is important, it is not always assured, and Part 133 does not address the risk of recovery from an inadvertent IMC entry event,” Mr Mitchell said.
Outcomes
The report outlined the management of the risk of inadvertent IMC relied on ‘multiple layers of control’, including training and procedures for both avoidance and recovery, which can be enhanced by equipment such as autopilot, terrain awareness and warning systems.
Mr Mitchell acknowledged the operator had taken several actions as a result of the accident including introducing basic instrument flying training and inadvertent IMC recovery training, updating its syllabus to include knowledge and checks for avoiding and recovering from inadvertent IMC, and upgrading the avionics systems on its helicopter fleet to incorporate various technological aids including autopilot where available.
The ATSB has also recommended CASA take further safety action to address the risk of inadvertent IMC events in its helicopter passenger operation regulations.
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