What happened
On 9 March 2017, a Mainair Blade, registration G-CCXR, was conducting a private local flight near Haverfordwest Airfield. The flight took place during the evening, approximately one hour before sunset, under conditions of good visibility and light westerly winds. The pilot was navigating south along the River Cledlam, maintaining an altitude of roughly 500 ft amsl and a speed of 60 mph.
As the aircraft turned westward to follow the river, the pilot encountered significant glare from the low sun. In an attempt to shield his eyes by using his hand against his helmet visor, the pilot unintentionally reduced engine power by relaxing pressure on the foot throttle. This led to an unplanned descent. During this low-level flight, the pilot suddenly identified power lines and supporting pylons directly in his path.
To avoid the obstruction, the pilot executed an evasive manoeuvre involving a leftward push on the control bar and a climbing right turn. This sudden movement, combined with a further reduction in power, caused the aircraft's airspeed to drop rapidly, resulting in a wing stall. The aircraft subsequently fell out of control and impacted the river. The pilot was able to exit the submerged aircraft and swim to the shore, though he required treatment for hypothermia.
The investigation
The investigation focused on the visibility of the obstruction and the pilot's control of the aircraft. It was noted that the power lines in question cross the river approximately two nautical miles northeast of Pembroke Dock. While the pylons are recorded on certain topographical charts, they are not featured on the ICAO 1:500,000 Aeronautical Chart, as that specific chart does not typically include obstructions below 300 ft agl.
Findings
- The pilot's forward vision was significantly impaired by the glare from the low sun.
- The aircraft was flying at a low altitude toward an unexpected obstacle.
- The unintentional reduction of engine power via the foot throttle contributed to the loss of altitude and subsequent stall during the evasive manoeuvre.