Collision du Nimbus 2C avec une ligne de chemin de fer lors de l'approche à Montricher, Suisse

Le 12 mai 1990, un Schempp-Hirth Nimbus 2C a été impliqué dans une collision avec une ligne de chemin de fer lors de son approche de l'aérodrome de Montricher en Suisse. Le pilote, revenant d'un vol d'entraînement, a rencontré des courants descendants et n'a pas pu maintenir une altitude suffisante. Malgré des tentatives pour éviter l'obstacle, le planeur a heurté la ligne aérienne du chemin de fer, causant des dommages importants à la fois à l'appareil et à l'infrastructure ferroviaire. Le pilote a subi des blessures légères. L'enquête a confirmé que l'accident résultait d'une altitude insuffisante pour éviter l'obstacle.

1. Cross-country return: After a training cross-country flight from Montricher toward the Jura, the pilot turned back near La Chaux-de-Fonds due to deteriorating weather and flew toward Montricher with sufficient altitude to arrive but with little reserve.
2. Prolonged sink encountered: While following the eastern slopes of the Jura on the return leg, the glider flew through a large area of descending air, reducing altitude to about 1200 m AMSL near Romainmôtier, 7.5 km from the airfield.
3. Low height margin: At L'Isle, about 3 km from Montricher, the pilot judged he had just enough altitude to reach runway 21 directly but without any height reserve to follow a normal circuit and standard approach.
4. Continued direct low approach: Despite recognizing the minimal height margin and the presence of suitable fields below, the pilot elected to continue a straight-in, downwind approach to runway 21 instead of committing to an outlanding.
5. Attempt to clear railway: Approaching the Biére–Apples–Morges railway line and realizing he could not overfly it with his remaining height, the pilot dived to gain speed and then pulled up in an attempt to 'jump' over the overhead wires.
6. Impact with catenary: During the pull-up maneuver the glider’s left wing struck the railway catenary, causing the aircraft to pivot about a quarter turn to the left and lose control.
7. Crash - minor injury: The glider crashed onto the road alongside the railway, sustaining severe damage and causing major damage to the railway installations, while the pilot received only minor injuries.