What happened
On July 18, 2018, at approximately 18:10 local time, a Cessna 172 N and an ASW 20 glider collided northwest of the Borken-Hoxfeld landing field in Germany. The Cessna 172 N, operating a sightseeing flight with three passengers, was traveling southwest at an altitude of approximately 420 meters. Simultaneously, the pilot of the ASW 20 was performing a series of left-hand turns to lose altitude while preparing to land after a seven-hour cross-country flight.
According to statements from the occupants of the Cessna, the glider had been visible in their field of view for at least one minute. The pilot of the Cessna reported attempting a rightward course correction to increase separation while conversing with passengers. However, the pilot of the glider noted that as they transitioned from right-hand to left-hand turns, a collision course developed. The glider pilot initiated a steep climb in an attempt to avoid the aircraft, but the collision occurred approximately two seconds later.
Following the impact, both aircraft remained airworthy and were able to return to their respective departure airfields. There were no injuries to the pilot or the three passengers in the Cessna.
The investigation
The BFU investigation utilized radar data and GPS tracks from the glider to reconstruct the flight paths. The data confirmed that the Cessna was flying in a straight path while the glider was executing turns. The investigation established that approximately four seconds before the collision, the glider changed its direction of turn from right to left, placing it on a path that intersected with the powered aircraft.
Physical inspections of the aircraft revealed significant damage. The ASW 20 suffered delamination and structural failure of the right wing, with a 1.5-meter section of the wingtip being severed during the impact. The Cessna 172 N sustained damage to the lower third of its left strut, including buckling and paint transfers from the glider.