What happened
On June 1, 2004, at approximately 08:30 local time, a Piper PA-36-285 (registration EC-CUU) was performing agricultural spraying operations near Granátula de Calatrava, Spain. The aircraft was attempting its first flight of the day from a farm track being used as an improvised runway because the primary strip was overgrown with grass. The aircraft was carrying approximately 600 liters of water mixed with pesticide.
The available takeoff distance on the track was only 500 meters. During the takeoff roll, the pilot applied maximum power, but the aircraft failed to lift off. In an attempt to reduce weight, the pilot activated the emergency discharge, releasing approximately two-thirds of the load. Despite this, the aircraft only managed to lift a few meters above the ground as it reached the end of the track. The pilot then released the remaining load, but the aircraft could not maintain flight, veered to the right, and descended into an olive grove.
The aircraft struck several trees, causing the right wing to break and the horizontal stabilizer to detach. The aircraft eventually came to rest after a 90-degree turn into another row of trees. The pilot, who was the sole occupant, escaped the wreckage uninjured.
The investigation
The investigation focused on the aircraft's weight, the takeoff configuration, and the suitability of the improvised runway. Investigators determined that the aircraft's total weight at takeoff was approximately 2,004 kg, which was slightly above the maximum takeoff weight of 1,996 kg.
Technical inspections of the engine and flap systems showed no mechanical failures. However, investigators found that the control column knob had been replaced with an undocumented part that did not match the official parts catalog. The pilot believed this knob contained a flap switch, which may have led to the unintended retraction of flaps during the takeoff roll. Furthermore, while the takeoff distance required for the aircraft's weight was calculated at 490 meters, the 500-meter track was highly constrained by its narrow width and initial curves, which likely hindered acceleration.
Findings
- The aircraft was operating at a weight exceeding its maximum takeoff weight.
- The takeoff runway length was insufficient for the aircraft's weight and configuration.
- The aircraft was operated without the use of flaps, which would have increased lift and shortened the required takeoff distance.
- The improvised runway was narrow and featured directional changes that likely impeded the takeoff roll.
- An undocumented modification to the control column knob created confusion regarding flap operation.