What happened
On June 25, 1999, a near-collision occurred at the Jämijärvi aerodrome during a local Midsummer festival. A formation of four Hawk Mk51 training jets, performing a flyover for the event, entered the airspace at approximately 15:30 local time. Simultaneously, a Cessna FR 172E, registration OH-CNB, was conducting a skydiving operation, dropping four jumpers in the same area.
The formation of jets approached the runway at a speed of approximately 650 km/t and an altitude of 200 meters. The flight leader had attempted to contact the aerodrome via radio but used an incorrect frequency due to an error in his reference table. Because there was no response on the frequency he was monitoring, the leader assumed the airspace was closed for the event and continued the maneuver.
During the flight, the formation passed extremely close to the first skydiver. While the flight leader estimated a separation of 200–300 meters, the skydiver reported the jets passed only 30–80 meters vertically and 50–70 meters laterally from his position. The formation later encountered three more parachutes in the area. The skydivers, unaware of the military flight, were forced to consider emergency procedures to avoid the high-speed aircraft.
The investigation
The investigation examined the coordination between the event organizers, the military flight leader, and the skydive operation. It was established that the event organizers had requested the flyover but failed to take necessary steps to clear the airspace or warn other aircraft of the upcoming military presence.
The investigation also scrutinized the flight leader's preparation. It was found that the leader relied on an incorrect frequency table that listed the wrong identifier for the Jäkäläpää aerodrome, leading him to use the wrong radio frequency. Furthermore, the flight leader had not verified the current Jämijärvi aerodrome information via the Aeronautical Information Publication (AIP) prior to the flight, nor had he contacted the event organizers.
Findings
- The primary cause of the near-collision was that the event organizers failed to warn other air traffic of the scheduled flyover.
- The flight leader's lack of preparation, specifically failing to verify aerodrome frequencies via the AIP, contributed to the lack of communication.
- The flight leader used an incorrect radio frequency because he misread a frequency table that contained an error regarding the Jäkäläpää aerodrome identifier.
- The skydivers and the pilot of OH-CNB were unaware of the military formation's presence until the encounter was already underway.
- The high speed and tight formation of the Hawk Mk51 jets, combined with the low maneuverability of the skydivers, created an extremely hazardous situation.