Incident de Ka 4 Rhönlerche près de Niedermuhlern lors d'un vol d'entraînement

Le 12 mai 1963, un Alexander Schleicher Ka 4 Rhönlerche II a été impliqué dans un incident près de Niedermuhlern, en Suisse. Le planeur, piloté par un élève pilote, effectuait un vol d'entraînement depuis l'aérodrome de Bern/Längenberg. Le pilote a rencontré des difficultés pour retourner à l'aérodrome en raison d'une perte d'altitude dans des vents forts. L'appareil est descendu dans une zone boisée, où il s'est emmêlé dans les arbres. Le pilote est resté indemne, mais le planeur a subi des dommages importants aux ailes.

1. Training thermaling flight: Student pilot on a solo training flight departed Bern/Längenberg by aerotow for a planned 30–35 minute soaring flight in local thermals and hang lift.
2. Drifted behind ridge: While using hang lift, the student allowed the glider to be carried about 5 km behind the Längenberg ridge line, contrary to the instruction to remain in the airfield zone.
3. Low experience student: The pilot was a relatively inexperienced glider student with limited solo time and made optimistic tactical decisions about remaining in lift and returning.
4. Headwind on return: On attempting to return toward Längenberg, the glider encountered headwind and general sink, causing rapid loss of altitude and making it increasingly doubtful that the airfield could be reached.
5. Delayed outlanding decision: The pilot persisted in trying to get back toward the ridge and airfield, misjudging height and only deciding on an outlanding after descending to about 200 m above ground near Niedermuhlern.
6. Low turn near obstacles: Approaching houses, a power line, and a small wooded depression, the pilot initiated a low-altitude avoiding turn at roughly 15–20 m above ground, during which the glider, likely already near the stall, sank further and the left wing struck tree tops.
7. Outlanding - damage: The glider descended into a small wooded area and came to rest hanging in the trees with both wings heavily damaged, while the pilot remained uninjured.