What happened
On 12 October 2009, a Pilatus PC-9(M) operated by the Irish Air Corps was conducting a navigation-training exercise under Visual Flight Rules (VFR). The flight originated from Casement Aerodrome in Baldonnel, Co. Dublin, with Galway Airport as the intended destination. The crew included an instructor and a cadet acting as the handling pilot.
During the cross-country mission, the aircraft traveled toward Maum, Co. Galway. As the flight approached the western edges of Lough Mask, weather conditions ahead began to worsen. While maintaining visual contact with the ground, the aircraft crossed a ridge into a steep, narrow valley. During this phase, the aircraft entered cloud cover while performing a series of steep turns and climbing on a northerly heading. Following this, the aircraft entered a rapid nose-down attitude and a right roll, ultimately impacting the northern slopes of the valley at high speed in a steep, nose-down, wings-level orientation. The impact resulted in two fatalities and the total destruction of the aircraft.
The investigation
The AAIU investigation focused on the sequence of maneuvers and the environmental conditions leading to the impact. Investigators examined the flight path, the transition from visual to instrument conditions, and the physiological factors affecting the crew. The inquiry also addressed a period of delay in the report's publication due to a legal notice of re-examination, which was ultimately dismissed by the Minister for Transport.
Findings
- The aircraft entered cloud cover while executing steep turns and a climb.
- The crew experienced a loss of situational awareness during the transition into the clouds.
- The primary cause of the accident was Controlled Flight Into Terrain (CFIT).
- The crash was precipitated by spatial disorientation, specifically triggered by a somatogravic illusion.