What happened
On March 5, 2023, at 11:14 local time, a Eurocopter AS-355N, registration EC-JMK, crashed into the left slope of a valley near Robledo de Chavela, Madrid. The aircraft, operated by the Directorate-General for Traffic (DGT) Aerial Resources Unit, was performing a state flight intended for traffic surveillance and assistance along the national road network.
During the flight, the aircraft was maneuvering at a very low altitude and low speed. The investigation established that the helicopter began to lose speed and altitude approximately 76 seconds before impact. The aircraft experienced an unanticipated yaw that lasted for eight seconds immediately preceding the collision. The impact occurred at the KM 2,400 point of the M-512 road. While the pilot escaped without injury, the air surveillance operator and a passenger sustained serious injuries as the aircraft rolled onto its left side upon impact.
The investigation
The CIAIAC examined flight recordings from the WESCAM PEGASUS surveillance system, the ENAIRE SACTA air traffic control system, and various interviews. The investigation revealed that although the flight was scheduled for surveillance, the aircraft had been flying between targets for 14 minutes without performing actual traffic monitoring. Furthermore, the investigation found evidence of unstable flight characteristics, including inconsistent speed and altitude control, and instances where the pilot did not adhere to minimum flight altitudes.
Investigators also looked into the aircraft's Emergency Locator Transmitter (ELT), finding it was inoperative due to being set to the OFF position and having insufficient battery power. Additionally, the investigation scrutinized the organizational structure of the DGT's Aerial Resources Unit, noting a lack of external oversight and a lack of defined procedures for various mission phases.
Findings
- The primary cause of the accident was a loss of control of the aircraft while flying at a low altitude and low speed in a challenging terrain environment, where tailwinds were incorrectly assessed and managed by the pilot.
- The pilot failed to recognize the developing situation and did not implement corrective control actions.
- The safety culture within the DGT's Aerial Resources Unit was characterized by an informal approach and a lack of standardized procedures.
- There was insufficient supervision of the unit's operations due to the existing legal and organizational framework.
- The aircraft was flying in a manner that included unauthorized maneuvers rather than strictly adhering to surveillance protocols.