Piper PA 28-235 Cherokee accident at Col du Sac (HB-PQH)

Flight details and accident sequence On 20 June 2017, a Piper PA 28-235 Cherokee registered HB-PQH departed Geneva Airport at 21:50 local time for Caen Airport. The flight was a VFR night navigation training flight operated by a club, with a pilot and an instructor on board. Four minutes after takeoff, near reporting point “W” at about 3,300 ft, the controller asked the pilot to call when passing reporting point “SW.” The pilot instead requested to head toward the Jura ridges, which the controller accepted. The aircraft then turned toward Col du Sac and continued climbing. During the climb, around 21:58, the stall warning activated. The pilot alerted the instructor, who took control and found the aircraft facing the mountain and close to a stall. Seconds later, the aircraft collided with trees and crashed on the eastern slope of the mountain. Both occupants evacuated before a fire broke out. ## Site, wreckage, and performance The accident site was on the eastern slope, about 50 ft below Col du Sac. The aircraft struck the treetops with a low attitude and high energy. The left wing was torn off during the collision with trees, and the aircraft then hit a rock before coming to rest. A fire followed, and almost the entire aircraft burned. Visual examination of the propeller blades indicated the engine was producing power. Flight controls were continuous at impact. ## Crew experience The 28-year-old pilot held a Swiss PPL(A) obtained in May 2017 and had about 90 flight hours, including 30 as pilot-in-command. The 50-year-old instructor held a Swiss ATPL(A) and an FI(A) qualification since 2015, with about 5,200 flight hours and 200 instruction hours. ## Weather and lighting At Geneva Airport at 21:50, the wind was 250° at 7 kt, visibility was CAVOK, temperature was 27 °C, dew point 16 °C, and QNH 1017 hPa. Aeronautical night began at 22:08. The accident occurred in twilight conditions, which can reduce contrast sensitivity and degrade distance and terrain perception. ## Investigation findings The pilot gradually increased the aircraft’s pitch to keep a constant gap between the ridge line and the top of the engine cowling. This reduced speed until the stall warning activated. At that point, the safety margin from the terrain was insufficient to recover before impact. The pilot was focused on the ridge line at the expense of monitoring flight parameters. The instructor had been focused on a tablet after a navigation software error and was not able to correct the pilot’s path. Twilight lighting likely degraded visual perception, and high temperature may have reduced engine performance. The accident resulted from incorrect management of the aircraft’s trajectory during a ridge crossing, inadequate monitoring of flight parameters, and insufficient consideration of aircraft performance by the pilot and instructor.