What happened
On March 24, 2001, an ambulance helicopter flight was conducting a medical transport mission in Tierp, Sweden. After dropping off medical personnel at a nearby snow-covered area, the commander determined the initial landing site was unsuitable for parking due to its proximity to a road and the difficulty of moving a patient over a snow bank. The commander requested the co-pilot to scout a nearby parking lot to evaluate it as an alternative parking location.
Upon receiving a thumbs-up signal from the co-pilot, the commander maneuvered the Sikorsky S7．6A++, registration SE-JUZ, over a row of trees toward the parking lot. As the aircraft descended, the rotor wash disturbed snow and sand, forcing the co-pilot to shield his eyes. Simultaneously, the pilot observed a plastic bag swirling toward the rotors. To prevent the debris from being ingested, the pilot executed a rapid touchdown. During this maneuver, the tail rotor struck tree branches located at the edge of the parking lot, causing damage to the rotor blades.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the landing site, the aircraft, and the operational procedures of the operator. The investigation focused on the suitability of the chosen landing area and the coordination between the two crew members. Investigators reviewed the company's Flight Operations Manual (FOM), which requires an obstacle-free landing area of at least 32 meters in all directions. The investigation also looked into the lack of established ground marshalling protocols and the equipment used by the crew during the maneuver.
Findings
- The chosen landing site was approximately 29 meters wide, failing to meet the company's minimum safety margin of 32 meters.
- The parking lot was deemed unsuitable due to the proximity of buildings and parked vehicles.
- The tail rotor collided with tree branches because the safety distance to the nearest obstacle was insufficient.
- The pilot's decision to land quickly was influenced by the need to avoid a flying plastic bag being sucked into the rotor.
- There was a lack of established routines for crew cooperation during ground marshalling.
- The co-pilot was not utilizing a portable radio to communicate with the commander and was positioned in a way that prevented effective monitoring of the landing.