What happened
On August 24, 2005, an Air Tractor AT-802A, registration EC-JKK, was participating in a coordinated aerial firefighting mission near S. Pedro do Sul, Portugal. The aircraft was operating as the second plane in a pair, following a lead aircraft to drop retardant on a forest fire in the Chão do Couto area.
As the pilot attempted the drop, the primary water discharge doors failed to open. To rectify the situation, the pilot had to switch to the emergency discharge system. This necessary intervention caused a critical delay in the aircraft's recovery maneuver. While attempting to regain altitude and airspeed by applying maximum power, the aircraft—which was flying at a low altitude and low speed—was unable to clear the terrain. The aircraft struck trees and plummeted to the ground. The pilot successfully evacuated the wreckage and sustained only minor abrasions.
The investigation
The GPIAAF investigation examined the wreckage and the operational circumstances of the flight. Investigators found that the aircraft's engine and propeller systems were functioning correctly, and no mechanical failure was found in the engine itself. While the primary discharge system failed to actuate, the emergency system functioned as intended.
The investigation also reviewed the pilot's experience, noting that while the pilot was qualified, they had very limited experience (approximately 50 hours) in this specific aircraft type and had only performed aerial firefighting operations in this environment for a few days prior to the accident. Furthermore, investigators noted that the aircraft's flaps were found in the retracted position, contrary to the recommended 10-degree setting for the drop maneuver.
Findings
- The primary cause of the accident was a delay in the recovery maneuver following the water drop, which led to a collision with trees.
- The failure of the primary discharge doors forced the pilot to focus on the cockpit to activate the emergency system, delaying the pull-up.
- The aircraft was flying at a critically low altitude and speed, leaving little margin for error.
- The aircraft was not in the recommended configuration, as the flaps were retracted.
- Environmental factors, including moderate to strong turbulence caused by the terrain and the heat from the active forest fire, further hindered the pilot's ability to recover the aircraft.
- The pilot's limited experience with this specific aircraft type and the high-intensity firefighting environment contributed to the difficulty in managing the emergency.