What happened
On November 3, 2020, at 11:56 local time, an Air Tractor AT-401, registration EC-EIZ, crashed near a forest track in the municipality of Orihuela, Alicante. The flight was being conducted by a pilot performing his first flight in this specific aircraft type. The objective was a short-duration, low-altitude flight (between 300 and 500 feet AGL) to familiarize himself with the aircraft's handling.
Following takeoff, the pilot performed several turns near the landing strip. An experienced pilot, who had flown the same aircraft shortly before the accident, was observing the flight from the ground. This witness noted that the aircraft was flying at an inadequate speed and exhibited a tail-low, nose-high attitude. As the pilot attempted a right-hand turn, the aircraft entered a stall and impacted the ground in a nearly vertical attitude. The impact destroyed the aircraft, and the pilot sustained serious injuries.
The investigation
The investigation examined the pilot's experience, the aircraft's mechanical state, and the flight planning. The pilot had significant flight time in lighter, tricycle-gear aircraft, such as the Cessna 172, but had no prior experience with the more powerful and tailwheel-configured AT-4/01.
Investigators analyzed the engine controls and found that the throttle friction screw was inadequately tightened. Due to the high vibrations produced by the engine, the throttle lever had drifted backward, leading to a reduction in power. Furthermore, the investigation found that no radio communication was established between the pilot and the observer on the ground, preventing the experienced pilot from providing verbal assistance during the developing emergency. The flight planning was also criticized, as performing low-altitude maneuvers with flaps partially extended was deemed inappropriate for a first flight in the type.
Findings
- The primary cause of the accident was the loss of control of the aircraft following an aerodynamic stall at low altitude.
- The pilot failed to recognize the loss of airspeed and did not take corrective action by increasing power.
- The throttle friction adjustment was insufficient to prevent the engine controls from retreating due to engine vibrations.
- There was a lack of radio communication between the aircraft and the ground observer.
- The flight maneuvers performed were unsuitable for a pilot's initial familiarization flight in this aircraft model.