What happened
On the afternoon of March 29, 1959, a Moswey III glider, registration HB-372, was engaged in routine soaring operations near Dällikon. After being towed to the Lägern area, the pilot began performing a series of high-speed maneuvers involving steep dives and climbs. During these maneuvers, the pilot repeatedly descended toward the Lägern-Hochwacht viewpoint.
After two successful passes, the pilot attempted a third dive from an altitude of approximately 50 to 80 meters. During this third descent, the aircraft passed between a trigonometric signal and a lightning rod on a nearby barn. The aircraft's wings and tail struck the upper branches of a dense thicket, causing the glider to lose structural integrity. The wings and much of the tail were torn away, and the fuselage came to rest embedded in a tree approximately 150 meters below the viewpoint. The pilot sustained severe injuries, including multiple fractures, leading to permanent disability.
The investigation
The investigation, conducted by the Federal Office of Civil Aviation, examined the pilot's flight history, the airworthiness of the HB-372, and the environmental conditions. The investigation found that the aircraft was in a healthy condition with no mechanical defects or center-of-gravity issues. Weather conditions at the time of the accident were clear with light clouds and no wind. The investigation also noted that the pilot had previously admitted to performing similar low-altitude dives at the same location just days before the accident.
Findings
- The pilot performed high-speed, low-altitude maneuvers without any external necessity or provocation.
- The pilot's flight maneuvers were in direct violation of altitude regulations, which require a minimum height of 150 meters over ground in such areas.
- Loss of control occurred due to the aircraft striking ground obstacles (tree branches) during the maneuvers.
- The pilot either initiated the recovery from the dive too late or caused the aircraft to stall during the pull-up, leading to the impact with the vegetation.