Helicopter collision with cableway in Switzerland kills pilot

Casualties unknown • St. Niklaus, VS, CH

A commercial reconnaissance flight in the Mattertal valley ended in tragedy when an Eurocopter SA315B collided with a cableway line, resulting in three fatalities.

What happened

On February 28, 1999, an Eurocopter SA315B Lama, registration HB-XIB, was conducting a reconnaissance mission in the Upper Valais region of Switzerland. The mission, operated by Air Glaciers SA, was intended to survey avalanche damage and debris in riverbeds following heavy snowfall in the canton.

After completing several legs of the flight and transporting officials, the aircraft was flying toward St. Niklaus. At approximately 15:06 local time, the helicopter struck the northern carrier cable of a cableway installation. The impact caused the aircraft to disintegrate, and it fell onto the left bank of the Mattervispa river. The pilot was killed in the crash, and the two other occupants also sustained fatal injuries. The collision also caused significant damage to the cableway infrastructure.

The investigation

Investigators examined the wreckage and the flight path, noting that the aircraft was flying at a relatively low altitude and a steady speed at the time of impact. Evidence from the rotor blades confirmed that the main rotor struck the cableway's northern carrier cable.

Witnesses on the ground observed the helicopter flying on the right side of the valley, closer to the Embd side, rather than its usual flight path. The investigation also reviewed the meteorological conditions, which were clear with good visibility, but noted that the sun was low in the sky and the pilot was flying directly toward the sun. Furthermore, the investigation looked into the visibility of the obstacle, finding that the cableway was not marked with any daytime aviation warning markers, although such marking was not legally required at the time.

Findings

The pilot was flying at an insufficiently low altitude within an area containing numerous navigation obstacles.
The lighting conditions were highly unfavorable, as the pilot was flying against a low sun, which likely made the thin cable nearly invisible.
The pilot may have been flying closer to the obstacle to allow passengers to observe specific areas of interest, such as recent avalanche sites.
The cableway installation lacked any daytime marking to alert pilots to its presence.

Probable cause

The collision was caused by the pilot operating the aircraft at too low an altitude in an area with multiple obstacles, compounded by unfavorable lighting conditions that made the cableway wires difficult to detect.

Frequently asked questions

What happened in the 1999-02-28 AEROSPATIALE SA 315 B accident near St. Niklaus, VS, CH?

A commercial reconnaissance flight in the Mattertal valley ended in tragedy when an Eurocopter SA315B collided with a cableway line, resulting in three fatalities.

What aircraft was involved and where did it happen?

The accident on 1999-02-28 involved a AEROSPATIALE SA 315 B, registration HB-XIB, at St. Niklaus, VS, CH.

What was the probable cause of the accident?

The collision was caused by the pilot operating the aircraft at too low an altitude in an area with multiple obstacles, compounded by unfavorable lighting conditions that made the cableway wires difficult to detect.

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