What happened
On April 26, 1998, at 10:54 UTC, two Fouga Magister CM 170 aircraft, registered F-GKYD and F-GKYE, were involved in a mid-air collision near Saint Dominelar, France. The flight, operated by SA Yankee Delta, departed from Rennes St Jacques without a flight plan, intending to fly a visual flight rules (VFR) route between Rennes and Mont Saint Michel.
At the time of the flight, the weather was unstable due to a secondary cold front, characterized by rain showers and low clouds. The aircraft were flying at altitudes estimated between 300 and 600 meters. The aircraft F-GKYD was carrying a pilot and a passenger for a joyflight, while F-GKYE carried a pilot and a professional photographer documenting the formation for an aviation magazine.
During the flight, the pilots performed maneuvers that were not part of the approved aerobatic axis, which was currently located under the cloud base. Witnesses observed the two aircraft flying low and fast, maneuvering around each other, before they collided. The impact caused the tail section of F-GKYD to separate, leading the aircraft to fall into a steep descent and strike the ground. The second aircraft, F-GKYE, lost stability, struck trees, and eventually crashed into a wheat field. Both aircraft caught fire upon impact, resulting in 4 fatalities.
The investigation
The investigation focused on the wreckage of both aircraft and the flight circumstances. Investigators found that the debris from F-GKYD was dispersed along a 300-meter axis, with the tail section showing evidence of the collision. The impact between the two aircraft was described as a "rubbing" rather than a high-energy collision, as the deformation on the tail of F-GKYD was relatively light, though sufficient to break the fuselage at its narrowest point.
Investigators also examined the regulatory environment, noting that while an experimental aerobatic axis had been established for the area, the pilots were not utilizing it at the time of the accident. The investigation also looked into the pilots' recent experience, noting that both were highly experienced airline pilots (A340) but had only performed approximately two to two and a half hours of formation aerobatics per month in the preceding six months.
Findings
- The primary cause of the accident was the improvised execution of aerobatic maneuvers while en route to Mont Saint Michel.
- The presence of a professional photographer in the second aircraft likely pressured the pilots to attempt more complex maneuvers to capture better imagery.
- The pilots were not utilizing the designated aerobatic area, as the approved axis was obscured by clouds at the time.
- The pilots' recent experience in formation aerobatics was limited, as they were just beginning the new flying season.