What happened
On October 15, 1992, a pilot operating an AS350 B2 "Ecureuil" helicopter (HB-XSD) for Heli TV SA was conducting sling-load operations in the Calanca Valley. After completing several small tasks, the crew returned to Grono. The dispatch center then contacted the pilot regarding a new request from a client in Santa Maria in Calanca.
Despite poor weather conditions, the pilot agreed to investigate the site after the client predicted improving weather and implied that failing to take the job might result in losing future business to competitors. The helicopter took off from Grono with two flight assistants on board, carrying two empty concrete buckets suspended by a 10-meter cable.
The pilot landed approximately 200 meters from the loading site, then moved closer to assess visibility. Upon arrival, he and the client agreed that the transport should be postponed due to inadequate sightlines. However, shortly after takeoff from the material pickup point, the helicopter encountered thick fog banks. Within roughly 15 seconds of horizontal flight in these instrument meteorological conditions (IMC), the aircraft collided with dense forest canopy at a nearly level attitude. The helicopter was destroyed upon impact, and three occupants were seriously injured.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the technical condition of the helicopter, pilot qualifications, and weather data. The aircraft was found to be in perfect working order with no mechanical failures contributing to the accident. The pilot held valid licenses and had sufficient flight hours, though he sustained a severe head injury and could not recall the final moments of the flight.
Weather reports from Zurich indicated overcast skies with bases between 700 and 1,000 meters above mean sea level. While official data suggested visibility outside clouds was good, witnesses reported fog extending down to the tree tops at the crash site. The pilot had initially assessed the weather as critical but changed his mind after client pressure.
Findings
The investigation concluded that the accident resulted from the pilot's erroneous assessment of weather conditions and the subsequent decision to fly visual meteorological conditions (VMC) while inadvertently entering instrument meteorological conditions (IMC). Without visual references, maintaining control in dense fog is impossible, leading inevitably to controlled flight into terrain.
A significant contributing factor was the economic pressure exerted by the client. The investigation noted that the tense economic climate for helicopter operators often leads to a situation where safety factors are reduced or deprioritized to retain contracts. This psychological pressure on the crew played a crucial role in the decision-making process that led to the accident.
Safety action
The report highlights the systemic risk of commercial pressure in the helicopter industry. It suggests that operators and crews must be vigilant against external pressures that compromise safety margins, particularly when weather conditions are marginal or deteriorating.