What happened
On July 15, 2011, at 13:19 local time, an Eurocopter EC-135-T2, registration EC-JHT, was conducting a Helicopter Emergency Medical Service (HEMS) flight from Bilbao Airport to a football field south of Legazpi, Gipuzkoa. The flight was part of a commercial emergency medical mission.
As the crew approached the landing site, they selected a landing heading of 020° based on local wind conditions. While executing a right-hand turn to align with the field, the left side of the aircraft struck an electrical power line. The impact caused significant damage to the left side of the helicopter, including the left windshield, the co-pilot's door, and the left sliding door, which detached in flight. Additionally, the left side of the tail boom was struck, causing the left horizontal stabilizer to detach mid-air. Despite the impact, the pilot maintained control of the aircraft and successfully completed the landing at the intended site. All four occupants—the pilot, a HEMS crew member, and two medical technicians—remained uninjured.
The investigation
The CIAIAC investigation examined the flight path, the aircraft's condition, and the operational documentation provided to the crew. Investigators reviewed the landing site information sheet (ficha) used by the operator, Inaer Euskadi, S. A. U., which had been in use since October 2008.
Witnesses on the ground, including local municipal staff waiting at the field, confirmed seeing the contact between the aircraft and the cables. The investigation also analyzed the flight trajectory via GPS tracking and evaluated the crew's visual scanning during the approach. It was noted that the power line poles were located on the slopes of Mount Aizeleku and Mount Gorostiaga, approximately 720 meters apart.
Findings
- The crew had reviewed the landing site information sheet prior to the maneuver but was unaware of the electrical line's presence during the specific approach path used.
- The landing site information sheet contained inconsistent data; while the second page mentioned a power line for a 200° departure, the first page, which featured an aerial photograph of the 020° and 200° approaches, did not indicate any overhead obstructions.
- The flight path through the center of the valley at low altitude, combined with the wide spacing of the utility poles, likely prevented the crew from detecting the wires in time.
- Inaccurate information in the landing site documentation prevented the crew from identifying the hazard during their pre-flight planning and approach.