What happened
On April 14, 2004, at 13:26 UTC, two aircraft collided in mid-air over international waters in the Gulf of Lion, approximately 39 NM from Cap Béar, France. Both aircraft were engaged in specialized aerial fishing survey operations, specifically searching for tuna schools.
The first aircraft, a REIMS AVIATION FTB337G Skymaster, registration F-GFZH, departed Montpellier-Méditerranée, France, carrying a pilot and an observer. Shortly after, a CESSNA 337 Super Skymaster, registration EC-HEQ, departed from the same airport with a pilot and two observers. Both aircraft were operating under Visual Flight Rules (VFR) in Class G uncontrolled airspace at low altitudes.
At the time of the collision, the F-GFZH was performing tight right-hand turns over a detected tuna school. The EC-HEQ approached the same area and also began executing right-hand turns. The impact resulted in the total destruction of both aircraft. The collision claimed the lives of all crew members on the F-SBZH (two people) and all crew members on the EC-HEQ (three people), totaling 5 fatalities.
The investigation
The investigation reconstructed the flight paths using radar data from Montpellier. The analysis revealed significant radar garbling due to the extreme proximity of the two aircraft, which shared the same Mode A transponder code. This made it difficult to distinguish the individual trajectories in the final moments.
Investigators examined the operational procedures of both operators and the nature of the fishing survey activity. The investigation also looked into the visibility from the cockpit and the ability of the crews to detect approaching traffic while focused on the sea surface.
Findings
- The primary cause of the accident was the failure of the crews to detect the other aircraft or detecting it too late to take evasive action.
- The pilots' attention was likely focused on the sea surface to identify tuna schools rather than on flight monitoring and collision avoidance.
- The F-GFZH was performing tight turns, and its crew may have been unaware of the other aircraft's presence.
- The EC-HEQ crew may have initially detected the other aircraft but lost visual contact after completing a 360-degree turn, subsequently intersecting the other aircraft's path.
- The commercial nature of the activity and the lack of specific, standardized safety procedures for these aerial surveys contributed to the risk.
- Existing operator manuals did not include sufficient safety requirements or specific operational criteria to ensure safe separation during such specialized missions.
- There was a lack of effective oversight by competent authorities regarding these specific types of aerial fishing operations.