Mid-air collision involving SF-25 B and Piper PA-18 near Bern-Belp airfield

On May 13, 1973, a mid-air collision occurred near Bern-Belp airfield involving a Scheibe SF-25 B motor glider and a Piper PA-18 towing a DFS Kranich III. The collision happened at an altitude of 120-150 meters during the approach of the SF-25 B. The motor glider crashed, resulting in the fatalities of its pilot and passenger. The Piper PA-18 managed a forced landing south of the airfield, and the DFS Kranich III landed safely at Bern-Belp. The incident was attributed to an inappropriate flight path and inadequate airspace observation.

1. Self-launch training flight: The SF-25 B motor glider HB-2017 departed Bern-Belp on a local training flight with the pilot and his wife on board, later flying engine-off circles in the glider holding area.
2. Low recent experience: The motor glider pilot had not flown a motor glider since September 1972 and had very little recent powered or glider flight time, reducing his currency in the type.
3. Self-launch landing approach: With the engine stopped, the SF-25 B left the glider circling area over Hüenerhubel and flew a descending straight-in path toward the downwind leg (Gegengerade) for landing at Bern-Belp.
4. Converging with aerotow: At about 120–150 m AGL, the descending SF-25 B on a straight course toward the field converged nearly at right angles with a Piper PA-18 towing a Kranich III that was climbing out and turning left across the airfield.
5. Poor lookout and routing: The tow pilot flew the aerotow through the glider circling/approach area on an unsuitable departure path and did not adequately detect the motor glider, while the motor glider pilot may have been hampered by low sun glare.
6. Late evasive turn: Only 20–30 meters before impact, the SF-25 B pilot initiated a steep, slightly nose-high left turn in an attempt to avoid the tow, placing the aircraft briefly near knife-edge attitude.
7. Crash - fatal: The SF-25 B collided with the towplane, then entered a spiral dive and impacted the ground near Bern-Belp, destroying the motor glider and fatally injuring the pilot and passenger.