What happened
On September 2, 2023, at 13:42 UTC, a serious incident occurred involving two light aircraft operating under Visual Flight Rules (VFR) near the Køge reporting point. The first aircraft, a Diamond DA40 with registration SE-MCC, was conducting a flight training mission from Billund to Malmö Sturup. The second aircraft, a Tecnam P 2002 P-Mentor registered as OY-FFJ, was performing local flight training maneuvers near Roskilde.
During the flight, the air traffic controller at Copenhagen Information (COIF) East alerted the crew of SE-MCC to be vigilant for gliders in the area. Shortly thereafter, the crew of OY-FFJ notified the controller of their intention to switch to Roskilde Tower for landing. While the controller provided traffic information regarding SE-MCC to the crew of OY-FFJ, the controller attempted to contact SE-MCC multiple times via radio, but the crew of the Diamond aircraft failed to respond to any of the five attempts.
As the two aircraft approached each other near Ringsted, they passed with a radar-indicated horizontal distance of 1.2 nautical miles and a vertical separation of 100 feet. The flight instructor in OY-FFJ observed SE-MCC crossing their path from left to right. Recognizing the immediate danger, the instructor performed an emergency descending maneuver, which prevented a collision, resulting in a final vertical separation of approximately 100 feet.
The investigation
The Danish Accident Investigation Board examined the flight paths, radio communications, and meteorological conditions. The investigation established that the incident took place in daylight under Visual Meteorological Conditions (VMC) within Class G airspace. Radar data confirmed that the aircraft were at a very close proximity at the time of the encounter. The investigation also noted that the flight instructor in OY-FFJ had a partially obstructed view of the left side of the cockpit due to the student pilot and the window frame.