What happened
On November 19, 2004, between 11:50 and 12:10, four MD 500 training helicopters belonging to the Utti Jaeger Regiment flew into the active temporary danger area EF D121 Tähtelä near Sodankylä. The aircraft, with registrations HH-9, HH-10, HH-11, and HH-12, were performing a cross-country flight from Ivalo to their home base.
The pilots had gathered that morning in the Ivalo airport briefing room to prepare for the flight together, though they intended to fly as individual aircraft. During preparations, the pilots obtained weather information via text TV, telephone calls to a meteorologist in Rovaniemi, and by ordering a significant weather chart. While one pilot inquired about the activity of specific firing ranges, the crew did not request information regarding other danger areas and failed to obtain a VFR bulletin.
During the flight, the helicopters maintained an altitude of 30–100 meters. To avoid firing range D94, the pilots maneuvered into the active EF D121 area. At the time, atmospheric measurements were being conducted within the danger area using a tethered balloon. The helicopters passed the balloon's tether line at a distance of approximately 700 to 2,000 meters, but the pilots did not observe the balloon or its cable.
The investigation
The investigation examined the flight planning procedures, the availability of aeronautical information, and the status of the danger area. It was established that the pilots relied on fragmented weather sources and did not consult the AIP Supplement 65/2004, which had established the temporary danger area.
Investigators also looked into the information systems used by Rovaniemi air traffic services. The system in use (LVTJ) was found to be an older, manual-entry system with limited capacity, meaning not all NOTAM or AIP Supplement information had been updated in the system at the time of the incident. Furthermore, the investigation noted that while the Civil Aviation Administration published AIS and MET data online, these services had not yet been approved for operational use, and briefing rooms lacked the necessary internet terminals and printing capabilities to utilize this data effectively.
Findings
- The primary cause of the incident was that the pilots did not obtain a VFR bulletin or otherwise verify all active danger areas along their route, leading them to enter EF D121 while attempting to avoid range D94.
- The pilots' flight planning was incomplete as they did not review the relevant AIP Supplement.
- Information dissemination was hindered by the lack of access to modern digital aeronautical information at the briefing location.
- The pilots were not in radio communication with Rovaniemi regional air traffic control during the flight.