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A Van’s RV-7A light aircraft broke up in-flight after entering instrument meteorological conditions and its pilot became spatially disorientated, resulting in the loss of control of the aircraft, an ATSB investigation report details.
The amateur-built RV-7A two-seater, with the pilot the sole occupant and owner of the aircraft, was conducting a private flight under the visual flight rules (VFR) from Winton to Bowen, Queensland, on 23 April 2021. The pilot had been on a multi-day tour in company with three other pilots, each operating their own aircraft.
About 100 km into the flight, overhead Catumnal Station, the pilot most likely entered instrument meteorological conditions (IMC) and lost control of the aircraft several times, recovering control within 50 ft of the ground, before turning back towards Winton, recorded data shows.
However, about 11 km into the return leg, the pilot then resumed tracking to Bowen, climbing to above 10,000 ft and then operating at multiple altitudes between 10,000 ft and 500 ft above the ground, most likely to avoid weather along the track.
At about 90 km south of Charters Towers, the pilot again likely entered instrument weather conditions before becoming spatially disorientated, resulting in a loss of control of the aircraft. This led to exceeding the aircraft’s airspeed limitations, leading to the catastrophic failure of the airframe and the in-flight break-up.
“The ATSB found that the pilot departed Winton with a high risk of encountering adverse weather conditions along the planned route,” said ATSB Director Transport Safety Dr Mike Walker.
“There were no operational reasons for the pilot to continue the flight to Bowen, and the pilot probably had a self-imposed motivation or pressure to continue the flight.”
For a non-instrument rated pilot, even with basic attitude instrument flying proficiency, maintaining control of an aircraft in IMC by reference to the primary flight instruments alone entails a very high workload that can result in a narrowing of attention and the loss of situational awareness.
“The ATSB urges VFR pilots to avoid flying into deteriorating weather by conducting thorough pre-flight planning to ensure you have alternate plans in case of an unexpected deterioration in the weather, and to pro-actively decide to turn back, divert or hold in areas of good weather.”
Entering poor weather without the training and experience to do so can rapidly lead to spatial disorientation when the pilot cannot see the horizon.
“The brain receives conflicting or ambiguous information from the sensory systems, resulting in a state of confusion that can rapidly lead to incorrect control inputs and a resultant loss of control of the aircraft,” Dr Walker said.
Weather often does not act as the forecast predicts. Pilots must have alternatives available and be prepared to use them—even if it means returning to the departure point.
“Developing a ‘personal minimums’ checklist is an effective defence against what pilots often term as ‘push-on-itis’ or ‘get-home-itis’,” Dr Walker noted.
“A personal minimums checklist aids identifying and managing flight risks such as marginal weather conditions. It is an individual pilot’s own set of rules and criteria for deciding if and under what conditions to fly or to continue flying based on your knowledge, skills and experience.”
The ATSB’s Avoidable Accidents publication Accidents involving Visual Flight Rules pilots in Instrument Meteorological Conditions discusses a range of VFR into IMC accidents and details advice to pilots regarding how to the risk of being involved in such accidents.
Additionally, the Civil Aviation Safety Authority (CASA) has produced a number of educational resources including Weather to fly, an education program which focused on topics such as the importance of pre-flight preparation, making decisions early, and talking to ATC, and ‘178 seconds to live’, a campaign on highlighting the dangers of VFR flight into IMC.
Read the report: VFR into IMC and in-flight break-up involving Van's Aircraft RV-7A, VH-XWI, 90 km south of Charters Towers, Queensland, on 23 April 2021