What happened
On June 16, 1968, at approximately 13:13 CEST, an S-18 glider, registration HB-438, was performing a training flight at the Spreitenbach airfield. The aircraft was being operated by a student pilot under the supervision of a flight instructor. During the final approach to runway 28, a southwest wind caused the aircraft to drift to the right, resulting in a landing only a few meters away from another glider parked at the edge of the airfield.
Immediately following the initial touchdown, the right wingtip of the S-18 struck the left forearm of the flight instructor. At the time of the impact, the instructor was walking onto the landing strip, carrying a takeoff dolly. The force of the wingtip striking his arm, which was already under the weight of the dolly, resulted in a broken arm for the instructor. The glider sustained minor damage to its right wing.
The investigation
The investigation examined the flight conditions, the experience of the crew, and the sequence of events leading to the impact. The weather was reported as clear with good visibility and moderate winds from the southwest. The student pilot had recently begun transition training to the S-18 model, having previously only flown Rhönlerche gliders.
Investigators reviewed the actions of both the student and the instructor. The instructor, an experienced pilot with over 1,000 hours of gliding experience, had begun walking toward the takeoff area during the final approach to assist with the return of the aircraft to the launch site.
Findings
Two primary factors contributed to the accident. First, the student pilot failed to sufficiently compensate for the crosswind component, which caused the aircraft to drift off the intended centerline. Second, the investigation determined that the accident was caused by the inappropriate behavior of the flight instructor, who entered the path of the landing aircraft and failed to properly monitor its position or estimate its wingspan during the final phase of the landing.