What happened
On January 28, 2002, a loss of separation occurred within the Tampere-Pirkkala military control area (MIL CTA) involving two Finnish Air Force aircraft. A Hawk Mk51 (registration HW-344) and an F/A-18C Hornet (registration HN-421) crossed paths on intersecting flight paths, violating both lateral and vertical separation minimums.
The incident occurred during active training operations. The Hawk Mk51 was being directed by the coordination controller (COR) and was maneuvering through various headings as part of a descent. Simultaneously, a formation of Hornet fighters, led by HN-421, was operating within the KANGAS training area.
As the aircraft approached the intersection, the pilot of HN-421 detected the Hawk Mk51 on radar and subsequently made visual contact. To avoid a collision, the pilot of HN-421 initiated a climb. The pilot of HW-344 also observed the Hornet at a distance of approximately 500 meters before the aircraft crossed paths. During the encounter, the F/A-18C Hornet passed behind and above the Hawk Mk51 with a vertical separation of only approximately 140 meters and a lateral distance of roughly 400 meters.
The investigation
The investigation examined radar and cockpit recordings from both aircraft, as well as air traffic control and surveillance recordings from the 3rd Air Surveillance Center. Investigators interviewed the controllers involved, including the coordination controller (COR) and the arrival controller (ARR), as well as the pilots of both aircraft and the Tampere-Pirkkala air traffic control manager.
Findings
- The coordination controller (COR) was managing a high workload, directing approximately 7–8 aircraft simultaneously, in addition to several others on the frequency.
- The Hawk Mk51 was assigned a heading of 090 degrees at 1100 meters QFE, which directed it into the KANGAS training area where the Hornet formation was operating.
- The primary cause of the separation loss was the failure to maintain required vertical and lateral separation minimums between the two aircraft.
- The controller attempted to clear the Hawk Mk51 to 800 meters QFE to establish separation, but the instruction was not heard by the pilot because the transmission overlapped with another aircraft's communication.
- The Hornet formation had been vertically staggered for instrument approaches, with HN-421 at 1100 meters, but the intersecting path of the Hawk at the same altitude created the conflict.