What happened
On June 29, 2011, an Air Tractor AT-802A, registration EC-LBG, was engaged in aerial firefighting operations near L’Ampolla, Spain. The aircraft, operated by AVIALSA T-35, S.L., was part of a two-plane formation tasked with combating a fire in the Vendrell area. After performing initial water drops, the aircraft proceeded to the Ebro Delta to refill its tanks.
Following a successful water scoop by the lead aircraft, the pilot of EC-LOB attempted a similar maneuver in the same area, positioned slightly to the left of the first aircraft. While the aircraft had stabilized on the water at an appropriate speed, the pilot began the process of opening the scoops to intake water. At that moment, the aircraft experienced a sudden left yaw and heavy deceleration. The pilot attempted to correct the deviation using right pedal and increased power, but the aircraft quickly struck a submerged sandbank only 20–30 cm deep. The impact caused the aircraft to run aground, resulting in the detachment of both floats and significant structural damage to the fuselage, engine mounts, and propeller. The pilot escaped the wreckage uninjured and was rescued by a local fisherman.
The investigation
The CIAIAC investigation examined the flight sequence, the aircraft's maintenance history, and the environmental conditions. The investigation established that the pilot was highly experienced, with over 4,000 total flight hours and specific training for the AT-802A. The aircraft was also fully compliant with all airworthiness and maintenance requirements.
Investigators analyzed the lighting and water conditions, noting that high luminosity and reflections on the water surface, combined with shadows from passing clouds, made it difficult to perceive the shallow depth of the sandbank. Furthermore, the investigation reviewed the operator's documentation, finding that the chosen refueling location did not align with the company's established water points for the northern Ebro Delta. It was also noted that the company's internal documentation regarding this specific area was outdated and required revision following the accident.
Findings
- The primary cause of the accident was the impact against a submerged sandbank due to insufficient water depth in the chosen maneuver area.
- The pilot's perception of the water depth was compromised by environmental lighting conditions and surface reflections.
- The successful completion of the maneuver by the lead aircraft may have reduced the second pilot's perception of danger.
- The operator's manual lacked specific procedures for verifying water depth or managing operations in areas with varying light conditions.
- The company's documentation for water points in the Ebro Delta was not updated to reflect the current geographical characteristics of the area.
Safety action
- It is recommended that AVIALSA T-35, S.L. update its Operations Manual to include specific documentation regarding recognized water loading zones as part of the required onboard equipment.