What happened
On March 5, 2003, two aircraft engaged in training flights departed from Touss_le-Noble, France, on runway 07R. The first aircraft, a Cessna F150 registered F-BSIQ, departed for a VFR navigation flight toward Etampes. Two minutes later, a Socata Rallye MS 892 registered F-BLSO departed to perform maneuver exercises in the western sector of the Rambouillet VOR.
Both aircraft climbed to 1,500 feet, following parallel trajectories as they exited the circuit. While the crew of the F-BLSO maintained a parallel course, the student pilot in the F-BSIQ departed the frequency and initiated a left turn toward Etampes near Dampierre. During this turn, the two aircraft collided. The impact severely damaged the tail section of the F-BSIQ, causing the aircraft to lose control and strike trees near the village of Saint-Forget, resulting in two injuries to the crew. The F-BLSO sustained damage to its left wing and leading edge but was able to perform an emergency landing back at Toussus-le-Noble.
The investigation
The investigation focused on the flight paths and the level of situational awareness maintained by both crews. Radar data from the Orly primary radar and the transponder on F-BSIQ allowed investigators to reconstruct the trajectory of the Cessna. However, because the F-BLSO was not transmitting transponder signals, its precise relative position immediately before the impact could not be determined via radar.
Investigators examined the cockpit environment of the F-BLast and found that the instructor was focused on instructional tasks, such as marking reference points on the windshield for the student. The investigation also reviewed the airspace characteristics of Toussus-le-Noble, noting that the airfield's specific traffic patterns and the position of the control tower could contribute to increased collision risks.
Findings
- The primary cause of the accident was inadequate surveillance of surrounding traffic.
- The flight path chosen for the F-BSIQ did not allow for sufficient separation between the two aircraft.
- A contributing factor was the instructor in the F-BLSO shifting his attention from external monitoring to instructional tasks, which led to a failure to anticipate the sudden change in course by the other aircraft.
- The high-wing configuration of the F-BSIQ may have obstructed the student pilot's view of the F-BLSO during the left-hand turn.