Background
On 12 May 2012, a group of friends planned to fly from Perth Airport to Glenforsa on the Isle of Mull using four weight-shift microlight aircraft. The owner of G-CWIK, a Pegasus Quik (serial no. 8018, manufactured 2004), had purchased the aircraft in October 2011 and was taking flying lessons. On the day of the accident, the pilot, aged 63 with a Private Pilot’s Licence (Microlights) and 826 hours total flying experience (1 hour on type), and the owner (his passenger) arrived between 0700 and 0730 hrs to prepare the aircraft. G-CWIK had been refuelled the previous day. The group met at about 0800 hrs to discuss the flight, agreeing to travel independently and meet at Glenforsa for lunch.
Flight Description
The aircraft departed at 0920 hrs, with other group members departing between 0917 and 0927 hrs. Weather at Perth was good visibility with scattered clouds at about 4,000 ft. One pilot reported a headwind of 15-20 mph with moderate turbulence at 4,000 ft, so he climbed to 6,000–7,000 ft for smoother conditions. G-CWIK was last seen by another aircraft at about 6,000 ft northeast of Ben More, where it was seen to descend.
A GoPro Hero video camera attached to G-CWIK recorded the final 3 minutes 21 seconds of flight. The footage showed the aircraft descending above a small patch of stratus cloud, with the snow-capped summit of Ben More (elevation 3,850 ft) visible through a gap. The aircraft manoeuvred left and right to avoid cloud, then levelled off below the cloud base (about 300 ft above the summit) with increased engine speed. It descended slightly to about summit height, heading directly toward the mountain as if to pass over the top. The flight path appeared stable until about 300 m from the summit, when the aircraft began rolling and pitching. Engine speed increased significantly, the aircraft banked rapidly left and right, then pitched nose-down and impacted the mountain side.
A witness on top of Ben More saw the last moments but did not hear the impact due to strong wind. The wind at the summit was described as “very strong,” nearly ripping an item of clothing from his rucksack. He later met two hill walkers, and they discovered the wreckage. Both occupants were fatally injured.
Aircraft Information
The Pegasus Quik is a tandem two-seat weight-shift microlight powered by a Rotax 912 ULS piston engine driving a Warp Drive three-bladed propeller. G-CWIK was fitted with an optional electric pitch trim system and a GoPro Hero camera mounted on the forward strut. The Permit to Fly was renewed on 3 May 2012, and the airframe and engine had 438 hours. The wing, replaced in July 2010 after an accident, had 62 hours.
Accident Site and Wreckage Examination
The aircraft struck the south-eastern side of Ben More, 100 ft below the summit, consistent with hitting a small rock in a steep nose-down attitude with some left bank. The nosewheel and parts of the nose structure were embedded in the ground; the main wreckage was inverted 8 m away at 225°(M). The fuel tank was split and empty, with a distinct fuel smell. All three propeller blades failed near the root. The wreckage was recovered by helicopter on 16 May 2012 and transported to the AAIB facility for examination. All airframe and wing structure failures were attributable to impact forces. The pylon failed aft due to buckling, allowing the propeller to strike the wing. The aft keel and fin tube were deformed from propeller strikes. Lap straps from both seats failed in overload, but microlight harnesses are only required to restrain occupants under 9.0g forward and 4.5g upward loading—impact loads were considerably higher. The electric pitch trim motor was set to ‘six turns,’ which, with two occupants, would give an approximate trimmed airspeed of 60–65 mph.
Recorded Data
Two video files were recovered from the GoPro camera. The first covered 1 minute 4 seconds from about 25 km east-south-east of the accident site. The second, requiring forensic recovery, was 3 minutes 21 seconds long and ended with the aircraft in a steep nose-down attitude, estimated 10–20 ft above ground, within 20 m of the main wreckage. Audio analysis showed engine speed varied, increasing to maximum continuous 5,500 rpm 40 seconds before the end, then to redline 5,800 rpm, and finally to about 6,090 rpm 10 seconds before the end. Audio signatures disappeared 3.6 seconds from the end, coincident with extreme attitude changes.
Radar data from Kincardine and Lowther Hill heads (provided by NATS) showed the aircraft was not using a transponder and was tracked only by primary radar, with gaps due to terrain. The last radar return was 2.2 km east-north-east of the accident site. Other microlight aircraft in the area were flying several kilometres apart on different paths, consistent with GPS tracks from those aircraft. A helicopter secondary radar track showed a helicopter flying between Ben More and the adjacent peak below the peaks' height, but neither photographs nor video from that helicopter captured the accident aircraft.