What happened
On the evening of March 7, 2007, a collision occurred between two helicopters at the Stadtlohn-Vreden airfield during VFR night operations. The first aircraft, a Robinson R 22 Beta, was conducting a night training flight. The crew, consisting of a flight instructor and a student pilot, began their takeoff from runway 29. Approximately 75 meters into the takeoff roll, the R 22 Beta collided with an Eurocopter EC 120 B that was hovering over the runway.
The EC 120 B had recently completed five circuit patterns for a private flight and was in the process of vacating runway 29 via the first taxiway. During the impact, the rotor of the R 22 Beta struck the landing gear of the EC 120 B, causing a rotor blade to detach and the rotor system to stop abruptly. The R 22 Beta crashed onto runway 29 and was destroyed; the instructor and student sustained minor injuries but were able to exit the aircraft on their own.
The impact also severed the skid landing gear from the EC 120 B. The crew of the EC 120 B, which included a pilot, a co-pilot, and two passengers, performed an emergency landing on the grass strip adjacent to the runway. The aircraft sustained heavy damage, but all occupants remained uninjured.
The investigation
The BFU investigation established that all parties involved in the night operations had been briefed together prior to the flight and were aware of each other's presence. The investigation examined the flight paths, the aircraft condition, and the environmental factors, including the very dark night conditions (approximately 0.6 mlx) and the positioning of the aircraft on the runway and taxiway.