What happened
On July 6, 2007, a Cessna 172 M, registration OK-FKU, was conducting a VFR flight from Mnichovo Hradiště (LKMH) to Rakovník (LKRK) via the Louny waypoint. Approximately five minutes after takeoff, the pilot activated the SSR transponder. Shortly before passing over Louny at 2,20 and 2,200 feet, the pilot observed two JAS 39 Gripen fighter aircraft flying in close proximity to the light aircraft.
At 08:44 UTC, the Ground Controlled Intercept (GCI) station identified the aircraft as an unknown threat due to the transponder being set to code 7500, which signifies a hijacking. The military command classified the flight as a "suspected renegate" and ordered the immediate scramble of alert fighter jets. The interceptors took off at 08:52 UTC and subsequently identified the aircraft as the Cessna 172 M, OK-FKU.
Following the encounter, the pilot changed the transponder code to 7000 at 09:13 UTC and continued the flight toward Rakovník. Before entering the Rakovník control zone, the pilot switched off the SSR transponder. The pilot only realized the reason for the military presence after landing safely at LKRK.
The investigation
The investigation, conducted by the ÚZPLN and the Czech Air Force, confirmed that the pilot held a valid PPL with SEP qualification and a current medical certificate. The aircraft, OK-FKU, was fully airworthy, properly maintained, and properly insured. The investigation established that the weather conditions, the technical state of the aircraft, and the aerodromes involved did not contribute to the incident.
Findings
- The primary cause of the incident was pilot inattention during the operation of the SSR transponder, which resulted in the accidental input of code 7500.
- The military response was a direct result of the automated identification of the hijacking code by the GCI station.