What happened
On 7 June 2005, a PZL M18A, registration EC-FDN, took off from the Beariz firefighting base in Ourense to assist with a forest fire located approximately 30 km away. The aircraft, operated by Martinez Ridao Tratamientos Aereos, was performing its first flight of the day and was fueled to capacity for the mission.
Following standard procedure at the Beariz base, the aircraft began a 2/70-degree right-hand turn to avoid obstacles located to the north and west of the airfield. During this climbing turn, the aircraft entered a stall and plunged into a hill situated near the runway. The impact, which occurred at a steep 60-degree dive angle, resulted in the death of the pilot and the total destruction of the aircraft.
The investigation
The CIAIAC investigation examined the aircraft's performance, weight, and the regulatory framework governing its operation. Investigators reviewed the conflicting airworthiness approvals in effect at the time; while EASA Type Certificate A.056 imposed strict bank angle limitations, a Spanish Supplemental Type Certificate (STC-83S) allowed for much steeper turns at higher weights.
Technical analysis of the wreckage and engine components showed that the engine was operating at high power at the moment of impact and no mechanical malfunctions were found. The investigation also looked into the meteorological conditions at the temporary Beariz base, noting that high ambient temperatures and a lack of precise wind data at the site could have negatively impacted the pilot's ability to plan for the aircraft's performance.
Findings
- The primary cause of the accident was an aerodynamic stall during a climbing turn, characterized by a high bank angle and airspeed insufficient to maintain flight.
- The aircraft may have been operating at an excess takeoff weight, potentially exceeding the 5,300 kg MTOW limit.
- Conflicting regulatory standards allowed for a bank angle of up to 30° under the Spanish STC, which contributed to the loss of control.
- The aircraft's stall-warning system was disconnected at the time of the accident.
- The pilot lacked the minimum flying experience recommended by the manufacturer for such operations.
- The temporary nature of the Beariz base meant that accurate meteorological data, such as temperature and wind, was difficult to obtain, hindering proper pre-flight performance calculations.