What happened
On 7 March 2006, a British Aerospace Jetstream 3102, registration G-CCPW, was performing a passenger flight from Belfast City Airport to Ronaldsway, Isle of Man. During the third sector of the day, the crew was instructed by Air Traffic Control to back-track along Runway 04 to line up on Runway 22. The weather conditions at the time were dark with light drizzle and a visibility of 5 km.
As the aircraft taxied toward the threshold of Runway 20, the pilot was monitoring the red stop-end lights at the runway's edge. The co-pilot, while recording the ATC clearance, noticed the lights approaching and alerted the commander by shouting "Stop, Stop." The pilot applied the toe brakes immediately, but the aircraft's nose wheel had already left the paved surface. The movement caused the propeller tips to strike and break three runway stop-end lights.
There were no injuries to the two crew members or the 6 passengers on board. The aircraft and the airfield lights sustained damage during the incident.
The investigation
The AAIB examined the circumstances leading to the aircraft leaving the paved surface. The investigation focused on the pilot's ability to judge the distance to the runway end under the prevailing weather conditions. The commander noted that the use of intermittent windscreen wipers due to the drizzle may have caused water droplets to distort his depth perception, making the stop-end lights appear further away than their actual position.
Additionally, the investigation considered the possibility of pilot distraction. The commander suggested that a subconscious thought regarding the destination airport, Ronaldsway, might have contributed to the error, though the impact of the distorted vision was a primary focus of the inquiry.