Accidente del Pilatus B4 durante vuelo de entrenamiento cerca de Ulrichen, Suiza
El 29 de julio de 1987, un Pilatus B4-PC11AF estuvo involucrado en un accidente cerca de Ulrichen, Suiza, durante un vuelo de entrenamiento. El piloto, que volaba solo como parte de un campamento de vuelo en planeador alpino, soltó el cable de remolque a una altitud insuficiente de 2100 metros. A pesar de darse cuenta del error, el piloto continuó el vuelo para evitar regresar a Münster debido a restricciones de horario. El planeador entró en pérdida durante un giro y colisionó con una pendiente pronunciada. El piloto sufrió heridas graves y la aeronave fue destruida.
- Aerotow to ridge: During an alpine gliding camp, the pilot departed Münster in aerotow in a Pilatus B4 for a solo training flight along the Goms valley.
- Premature tow release: After a 180° turn near the Oberwaldergrimsel/Chietal area, the pilot released from tow at about 2100 m MSL, already below local ridge height contrary to prior instruction.
- Desire to avoid landing: Realizing she had released too low, the pilot nevertheless decided to continue the flight to avoid an early landing at Münster that would prevent another launch due to reservations.
- Low, slow ridge flying: In pure thermal conditions and with shallow local slopes, the pilot flew slow figure‑eight patterns close to the hillside, reducing height margin for corrections.
- Poor speed monitoring: The pilot flew mainly by feel and paid little attention to the airspeed indicator while maneuvering near the slope.
- Stall and loss of control: During a turn toward the valley at low height, the glider dropped below minimum flying speed, stopped responding properly to control inputs, and departed controlled flight.
- Crash - serious injury: The glider impacted a steep slope near Flieli, 1.5 km northwest of Ulrichen, seriously injuring the pilot and destroying the aircraft.