What happened
On July 17, 2021, a Bell 407 helicopter, registration EC-LBS, operated by Babcock Mission Critical Services España, was conducting a flight to validate a potential water collection point near Sabiñánigo, Huesca. The mission was part of a wildfire suppression campaign, specifically testing the viability of the "Pardina Zamora" reservoir for aerial water scooping.
The pilot, accompanied by six members of a helitransported brigade, had previously landed at the site to disembark the crew. After performing a series of maneuvers to test the water pickup process, the pilot attempted a second landing to re-embark the brigade. Due to heavy vegetation, the pilot positioned the aircraft further to the left than the initial landing.
During this maneuver, the pilot focused on monitoring the position of the Bambi Bucket using a mirror. While moving the aircraft forward, the rotor blades lightly grazed a terrain protrusion on the aircraft's 9 o'clock position. As the aircraft continued forward, the converging terrain walls caused a subsequent heavy impact between the rotor blades and the slope. This impact caused the helicopter to yaw, resulting in the tail rotor, vertical stabilizer, and left horizontal stabilizer striking the rock.
No injuries were reported among the pilot or the crew members who were on the ground at the time of the impact.
The investigation
The CIAIAC investigation examined the pilot's actions, the operator's fleet tracking capabilities, and the management of water collection points by the regional authorities. The investigation noted that the pilot did not request a ground guide (signaler) from the forest brigade, despite established procedures for confined area operations. Additionally, the pilot was not in active communication with the forest agent at the moment of the accident, as the agent had turned off his radio.
The investigation also highlighted a communication gap in the operator's fleet tracking system, which allowed for data transmission but did not permit direct two-way voice communication between the flight crew and the Operations Control Center (OCC). Furthermore, the investigation noted that the regional government of Aragon does not verify the operational status of water collection points prior to the firefighting season, unlike several other Spanish autonomous communities.
Findings
- The accident occurred in a confined mountain area.
- The pilot's attention was primarily focused on monitoring the position of the water bucket during the maneuver.
- The pilot made an error in distance perception regarding terrain obstacles near the landing zone.
- The pilot did not utilize a ground guide from the forest brigade to assist with the landing.
- The pilot was not in communication with the forest agent during the critical phase of the maneuver.