What happened
On March 19, 2022, a serious air traffic incident occurred at Roskilde Airport (EKRK) involving two aircraft on the final approach to runway 11. The aircraft involved were a Reims F172 M, registration OY-BSV, performing a flight training mission, and a Piper PA28-151, registration OY-TFK, operating a private flight.
At the time of the event, the traffic pattern for runway 11 was complex, with four aircraft performing right-hand approaches. A third aircraft, a Socata TB9 (OY-CDJ), was also part of the sequence. The incident began when the pilot of OY-CDJ inadvertently initiated an early base turn, which caused the aircraft to overtake the preceding aircraft, OY-BSCT. This change in the arrival sequence was communicated by the tower, but the pilot of OY-TFK did not register the updated information.
As OY-BSV was established on final approach, the pilot of OY-TFK was flying a cutting course from right base. To avoid a collision, the pilot of OY-TFK performed an evasive maneuver by flying underneath OY-BSV. Radar data indicated that the minimum horizontal separation between the two aircraft dropped to 0.0 nautical miles, with a vertical separation of only 100 feet.
The investigation
The investigation by AIB Denmark examined radar data, radio communications, and pilot testimonies. The investigators analyzed the sequence of events involving three aircraft: OY-CDJ, OY-BSV, and OY-TFK. The investigation reviewed the tower controller's instructions, specifically regarding the updated arrival order and the instructions given to the pilots to follow specific preceding aircraft.
Investigators also examined the environmental conditions, noting that the crew of OY-BSV experienced intense sunlight/glare on the right side of the final approach, which hindered their ability to maintain visual contact with other traffic. The investigation also looked at the pilot's focus, noting that the pilot of OY-TFK was primarily focused on following OY-CDJ, which led to a lack of awareness regarding the actual position of OY-BSV.
Findings
- The near collision was caused by divergences between the mental and factual traffic pictures held by the pilots.
- The pilot of OY-TFK was focused on following OY-CDJ and did not notice the updated traffic sequence communicated by the tower.
- The pilot of OY-BSV was unable to maintain visual contact with traffic on the right due to strong sunlight glare.
- The pilot of OY-TFK performed an evasive maneuver by flying under OY-BSV after realizing a collision course was imminent.
- The traffic density at the time was assessed as medium to high, contributing to the complexity of the situation.