What happened
On 15 January 2017, a Piper PA-30 Twin Comanche, registration G-ATMT, was conducting a private flight from Turweston Airfield to Chalgrove Airfield. After departing Turwestown and climbing to 2,000 ft amsl, the aircraft descended to approximately 1,000 ft amsl. At a point where a right turn would have facilitated a visual approach to the destination, the pilot instead executed a left turn toward rising terrain.
The aircraft proceeded northeast along a ridge of high ground, flying at an altitude of approximately 1,100 ft amsl. During this period, the aircraft was likely operating in Instrument Meteorological Conditions (IMC) while remaining below the Minimum Safe Altitude (MSA) of 2,200 ft amSB. The aircraft eventually struck the tops of trees at 920 ft amsl, resulting in extensive damage and the fatal injury of the pilot.
The investigation
The AAIB examined radar data, meteorological reports, and wreckage at the site near Aston Rowant Nature Reserve. Investigators found that the aircraft's flight path took it through areas of low cloud and poor visibility. While witnesses at Chalgrove reported better conditions, the aircraft was flying toward a ridge where the cloud base was significantly lower.
Physical examination of the G-ATMR wreckage showed the aircraft struck the trees in a wings-level, relatively flat attitude, suggesting the flight was under control at the moment of impact. There was no evidence of mechanical failure or pre-impact damage to the control systems. The investigation also considered the psychological aspects of decision-making, specifically how gradual weather deterioration can lead a pilot to inadvertently cross the boundary from Visual Meteorological Conditions (VMC) to IMC.
Findings
- The aircraft was flying in IMC for at least 1 minute 45 seconds prior to impact.
- The flight was conducted below the Minimum Safe Altitude (MSA) of 2,200 ft amsl.
- The pilot turned away from the intended destination toward higher ground and deteriorating weather.
- The aircraft struck trees at 920 ft amsl, leading to the fatal accident.