What happened
On June 29, 1997, a Swiss-registered Cessna 501 Citation, registration HB-VJB, was operating a taxi flight approaching Utti Aerodrome. While transitioning from an IFR to a VFR flight plan, the pilot requested a frequency change to contact Utti. The area controller provided an incorrect radio frequency, which was the frequency for Utti approach control rather than the local aerodrome information service (AFIS).
As a result, the pilot of HB-VJB began broadcasting position and altitude reports on the wrong frequency. Because the local AFIS had already closed for the day, no one responded to the transmissions. Unaware of any other traffic, the pilot continued the approach, eventually passing over the end of runway 07. During a turn toward the runway centerline, the pilot observed a skydiver in the air and noticed a Cessna 206G, registration OH-ULK, which had just released two jumpers.
The investigation
The investigation focused on why the aircraft were operating in such close proximity without communication. Investigators examined the air traffic control workstation setup and the status of the Utti AFIS at the time of the incident. It was established that the controller was using a frequency designator that had not been updated to reflect the recent change in Utti's radio frequency following the cessation of official AFIS hours.
Furthermore, the investigation looked into the status of the skydiving operations. While the controller was aware that skydiving was occurring in the uncontrolled (G) airspace, they could not confirm if the jump plane was currently airborne, as no airspace reservation had been filed for the area above 65 feet AGL.