What happened
On March 24, 1992, at approximately 18:50 local time, a pilot was operating an Airbus Helicopters AS 350 B2, registration HB-XVD, following its acquisition from TUI Air AG. The aircraft had been purchased for transfer to Altenrhein but was diverted back to the TUI Air base in Würenlingen due to deteriorating weather conditions en route toward Schaffhausen.
Upon returning to the airfield, the pilot intended to park the helicopter on a taxiway adjacent to a hangar for storage. To execute this maneuver, he performed a 180-degree rotation while maintaining forward momentum directly over the hangar structure. During this phase of flight, the tail boom struck the roof of the hangar. The impact caused the helicopter to spin uncontrollably around its vertical axis before crashing onto its left side just in front of the building.
The aircraft was destroyed, and the hangar sustained damage. Fortunately, the pilot emerged uninjured. At the time of the accident, it had already become night (sunset was at 19:18), but visibility remained adequate at approximately 5 km with light rain and variable winds of 5 knots.
The investigation
The Swiss Transportation Safety Investigation Board (STSB) examined the operational context and pilot qualifications. The pilot held a valid private pilot license for helicopters and had accumulated 319 total flight hours, including 80 hours in the specific AS 350 B2 model within the preceding 90 days. No health issues or incapacitation were identified as factors.
The investigation focused on the flight path and the mechanics of the maneuver. The base is surrounded by obstacles, requiring a relatively high approach profile. The pilot admitted to executing the reversal while the aircraft still possessed forward speed, which converted into backward motion during the turn. This specific tactical error placed the tail boom within the strike zone of the hangar roof.
Findings
The primary cause of the accident was an inadequate approach tactic. The pilot's decision to perform a 180-degree reversal while maintaining forward velocity over a confined area with overhead obstacles led directly to the collision. A more careful and calculated approach would have prevented the impact entirely.
Safety action
The investigation concluded that the accident was solely attributable to the pilot's operational error during the landing phase. No specific safety recommendations were issued beyond the implicit lesson regarding low-level maneuvering near fixed structures.