What happened
On July 13, 2004, at approximately 08:30 local time, a PIPER PA-36-375, registration EC-CQU, was performing agricultural spraying operations at an improvised dirt airstrip near Isla Mayor, Seville. The aircraft, operated by Agricolair, S. L., was carrying approximately 700 liters of insecticide and roughly 50 gallons of fuel.
During the takeoff roll, the aircraft briefly became airborne but subsequently lost altitude and returned to the ground. Although the pilot attempted an emergency discharge of the liquid payload to reduce weight, the aircraft continued to descend. The aircraft overran the end of the 650-meter runway, traveling through a grassy area before impacting an irrigation canal located at the end of the runway axis. The impact caused important damage to nearly all components of the aircraft, including the separation of the engine and engine mount from the main structure. The pilot escaped the wreckage without injury.
The investigation
The investigation examined the aircraft's weight, center of gravity, and environmental conditions. At the time of the accident, the aircraft's weight was estimated at approximately 4,600 lb, which was below the maximum authorized weight of 4,800 lb. Performance calculations indicated that the aircraft required roughly 1,500 feet of runway, while approximately 2,100 feet were available.
The pilot suggested that a tailwind gust prevented the aircraft from reaching rotation speed. Investigators analyzed the possibility of such a gust, noting that while the general weather was stable, the proximity to rice paddocks could create localized thermal updrafts and wind fluctuations. The investigation also considered that if the aircraft had been even 100 lb heavier than estimated, a gust of only 4 knots would have caused the described loss of lift.
Findings
- The aircraft was operating at a weight very close to its maximum allowable limit for the specific operational conditions.
- Small variations in environmental conditions were sufficient to degrade the aircraft's performance and prevent the achievement of necessary rotation speed.
- Localized thermal effects from the surrounding rice paddocks likely contributed to sudden changes in wind conditions.