What happened
On 4 April 2015, a Piper PA-28-140 Cherokee, registration G-BHXK, departed Dundee Airport for a private flight to Tiree Airport with two occupants. The flight began in good weather, but as the aircraft progressed westward, it encountered a warm front moving across Scotland.
At approximately 10:27 UTC, while cruising at 6,500 ft, the pilot acknowledged a weather report indicating misty conditions at the destination. Shortly after this communication, the aircraft began a gentle right turn. This maneuver gradually intensified into a tightening turn accompanied by a significant increase in airspeed and a rapid rate of descent. The aircraft eventually struck the western slope of Beinn nan Lus in a steep, nose-down attitude. Both the pilot and the passenger sustained fatal injuries, and the aircraft was destroyed.
The investigation
The AAIB examination of the wreckage focused on the structural integrity, engine performance, and flight controls. Investigators found no evidence of pre-impact mechanical failure or structural disintegration. The engine was found to be producing power at the moment of impact, and the primary flight controls remained attached to their surfaces, though they suffered overload failures during the crash.
Analysis of the aircraft's GPS track and radar data revealed that the flight path became erratic during the descent. The investigation also reviewed the pilot's training records, noting that while he had recently completed an IMC rating course, the rating had not yet been formally endorsed on his license. Meteorological data confirmed that the aircraft was flying near the freezing level, where moderate icing was a known risk.
Findings
- The aircraft likely entered Instrument Meteorological Conditions (IMC), either through a transition into cloud or due to a loss of visual reference.
- The transition from a controlled turn to a spiral dive is consistent with the pilot experiencing spatial disorientation.
- The aircraft struck the terrain at a high speed and a steep dive angle, suggesting the pilot may have been attempting to recover from an unusual attitude but lacked sufficient altitude.
- The presence of a warm front and the aircraft's altitude presented a risk of moderate airframe icing, which could have contributed to a loss of control.