What happened
On February 12, 2021, at approximately 13:16, a formation of four aircraft departed from runway 28 at Warsaw Babice (EPBC) airport. The group consisted of one Cessna 208B, registered as SP-WAW, acting as the lead aircraft, and three AT-3 aircraft. The flight was being conducted under a permit issued by the President of Warsaw.
Following takeoff, the aircraft performed a standard circuit pattern. To minimize interference with air traffic control, the flight crews transitioned from the tower frequency (119.18 MHz) to a secondary frequency (123.475 MHz) for internal formation communication. Because only the lead aircraft was equipped with two radios, the lead pilot was the only individual capable of monitoring both the tower and the formation frequency. The remaining three aircraft relied solely on the lead pilot for communication with the tower.
At approximately 13:40, the lead pilot accidentally muted the radio monitoring function on the primary tower frequency (COM1). Consequently, neither the lead pilot nor any of the other three crews maintained contact with the tower. Due to this loss of communication, air traffic control was forced to suspend or separate other aircraft operations in the vicinity. Communication with the formation was eventually restored at approximately 13:50, and all aircraft landed safely at 13:55.
The investigation
The PKBWL examined the sequence of events and the communication setup used during the formation flight. The investigation focused on the radio configurations of the participating aircraft and the procedures used to maintain contact with the tower while operating on a secondary frequency.
Findings
- The primary cause of the incident was the accidental muting of the radio receiver on the lead aircraft's COM1 station.
- There was no established or agreed-upon procedure for the flight group to follow in the event of a loss of communication during this specific type of formation flight.
Safety action
The incident was reviewed with the participating pilots and officials from the Warsaw Aero Club (ATO Aeroklub Warszawski). Emphasis was placed on strict adherence to procedures, the necessity of conducting thorough pre-flight briefings, and the importance of verifying communication links to prevent recurrence.