What happened
On June 23, 2003, an Aerospatiale SA 319B Alouette III, registration EC-FJA, was deployed for a firefighting mission to combat a cereal field fire located near Egea de los Caballeros, Zaragoza. The crew, consisting of the pilot, a forest ranger, and five firefighting crew members, was en route to the site when the fire was spotted shortly after takeoff. High temperatures of 40 °C and surface wind gusts were present at the time.
The pilot attempted to land approximately 30 meters from the fire on a flat area near a road. During the low-level approach, the aircraft struck a terrain feature at the rear, causing it to destabilize and crash. The impact broke the right-side skid, and the aircraft underwent violent oscillations as the rotor blades struck the ground before the helicopter overturned onto its right side. Following the impact, a fire erupted in the main gearbox area. Despite the pilot disconnecting the electrical and fuel systems, the fire spread rapidly, destroying the airframe, engine, and main rotor blades, leaving only the tail cone largely intact.
The investigation
The investigation focused on the landing conditions and the terrain characteristics at the site. The aircraft was operating over a large, uniform cereal field that was prepared for harvest. The terrain consisted of two distinct levels separated by a small embankment or drop-off (ribazo). Investigators examined the pilot's ability to perceive depth and distance during the final approach.
Findings
- The landing maneuver was significantly hindered by the lack of visual focal points within the uniform cereal crop, which prevented the pilot from accurately estimating the vertical distance to the ground.
- The terrain irregularities, specifically the vertical drop-off, were obscured by the nature of the vegetation.
- The primary cause of the accident was the pilot's failure to perceive the vertical drop-off in the terrain, which led to the tail cone striking the ground, destabilizing the aircraft, and causing the subsequent rollover.
- The onboard fire extinguisher was rendered inaccessible during the emergency because it was wedged between the pilot's seat and the right side of the cabin.
- All occupants were wearing seatbelts at the time of the crash; while most evacuated easily, one passenger required assistance from the pilot to release their belt.