What happened
On August 16, 2003, a Bombardier Canadair CL-415, registration I-DPCN, was engaged in aerial firefighting operations near Esine, Italy. After performing several successful water drops from Lake Iseo, the crew received instructions from the Fire Operations Director to perform a final drop at a specific ravine to extinguish remaining flames. Unlike previous maneuvers, this drop required an ascending approach trajectory rather than a descending one.
During the maneuver, the aircraft was in a climbing turn and was not in a stabilized condition. While navigating the steep terrain, the aircraft struck treetops and subsequently impacted the left flank of the valley at approximately 3,380 feet. The impact caused significant damage to the airframe, including a tree penetrating the rear fuselage. The two pilots managed to abandon the aircraft after noticing the onset of an engine fire, sustaining injuries, with one pilot being seriously hurt.
The investigation
The ANSV investigation focused on the flight dynamics, crew coordination, and operational procedures. Investigators examined the aircraft's technical condition, finding the engines were functioning at maximum power prior to impact and that no mechanical failures were responsible for the crash. The investigation also reviewed the flight manual of the operator, which stipulated that attack and escape routes should not be performed in a climb unless the elevation change was very limited.
Furthermore, the investigation looked into the communication between the crew and the ground coordinator. Because the commander was Canadian and did not speak Italian, the co-pilot handled all radio communications with the Italian-speaking fire director. The investigation also assessed the environmental conditions, noting the possibility of local convective turbulence caused by intense ground heating.
Findings
- The primary cause of the accident was an inadequate escape maneuver following the impact with trees.
- The crew failed to adhere to the operator's manual, which prohibited ascending attack routes in significant terrain.
- The aircraft performed the drop in an unstabilized state, executing the maneuver while in a climbing turn.
- A lack of effective crew coordination and information flow existed, as the commander was not directly privy to the Italian radio communications handled by the co-pilot.
- The crew did not conduct a new reconnaissance or briefing despite the change in the approach trajectory (from descending to ascending).
- Localized turbulence may have contributed to the loss of aircraft controllability.