Plan continuation bias probably influenced a pilot’s decision to continue their visual flight rules flight despite forecast unsuitable weather prior to a controlled flight into terrain accident west of Brisbane, an ATSB investigation report explains.
On the morning of 29 August 2022, a Cessna R182 Skylane RG operating an air transport (charter) flight with a pilot and two passengers on board collided with terrain in the D’Aguilar Range, about 36 km north-west of its destination of Archerfield Airport. All on board were fatally injured.
The Cessna had departed from Dalby toward forecast en route weather unsuitable for visual flight, despite the pilot only being qualified for flight in visual conditions.
After crossing a section of the Great Dividing Range below cloud, and with minimal terrain separation, the pilot continued the flight in similar conditions toward the Lake Manchester VFR route, adjacent to the D’Aguilar Range.
“The aircraft very likely entered cloud while manoeuvring in this area, resulting in the pilot losing visual reference with the ground, eventually leading to controlled flight into terrain,” ATSB Chief Commissioner Angus Mitchell said.
“The pilot was probably influenced by plan continuation bias – an internal pressure or desire to get to the destination – to continue the flight, which probably became stronger as they got closer to Archerfield,” Mr Mitchell said.
However, due to a lack of information, the ATSB was unable to determine the reasons why the pilot continued the flight at cruise speed and low level into unsuitable weather in the vicinity of known high terrain. The ATSB considered it unlikely that there was any direct or perceived organisational pressure on the pilot to continue the flight.
As the report notes, the safety risks of visual pilots flying into non-visual conditions are well documented.
“This Christmas period, especially with wet weather around the country, the ATSB urges all VFR pilots to be mindful of the subtle pressures of plan continuation bias,” Mr Mitchell said.
“Be prepared to amend and delay plans to fly due to poor or deteriorating weather and environmental conditions, and not to push on,” he said.
“Have alternate plans in case of unexpected changes in weather, and make timely decisions to turn back, divert or hold in an area of good weather.”
Mr Mitchell noted there is a range of reference material available to pilots with guidance on avoiding VFR flight into adverse weather, including from the US Aircraft Owners and Pilots Association Air Safety Institute, and the ATSB itself.
While not determined as a contributing factor in the accident, the ATSB also found the operator’s hazard and risk register did not identify inadvertent entry into non-visual conditions as a hazard.
“Not including inadvertent entry into non-visual conditions in its hazard and risk register – which formed part of the operator’s safety management system – reduced the operator’s ability to effectively manage that risk,” Mr Mitchell explained.
Since the accident, the operator has removed aeroplane operations from its Air Operator’s Certificate and, after a risk assessment, plans to implement two risk controls for its helicopter operations by February 2024.
First, the operator will update its operations manual to include a formal organisational policy for supporting pilots to land or return to a safe landing site if they assess that they will be unable to maintain visual meteorological conditions.
Second, annual operator proficiency checks will include techniques for avoiding, and recovering from, inadvertent entry into non-visual conditions.