What happened
On November 25, 2007, a Hawker 800 - H25B, registration D-CLBD, operated by Elbe Air Lufttransport GmbH, departed from Prague Ruzyně (LKPR) for Kyiv Borispol (UKBB). After receiving clearance for the VOZ 2A departure route and a climb to 5,000 ft, the aircraft departed runway 24.
Following takeoff, the aircraft deviated significantly from the assigned standard instrument departure (SID). Instead of following the prescribed track, the aircraft performed a right turn to a heading of approximately 360°. For roughly seven minutes, the crew failed to establish communication with Prague Approach (APP EC). During this period, air traffic controllers attempted to contact the aircraft via the primary approach frequency, the Ruzyně Tower frequency, other aircraft in the vicinity, and the international emergency frequency (121.5 MHz), all of which went unanswered.
At 14:07:50 UTC, the crew finally established contact with Prague Approach. Upon receiving an instruction to climb to FL 80 and turn left to a heading of 220°, the pilot instead executed a right turn, eventually turning to a heading of 150°. The controller subsequently issued corrective vectors to bring the aircraft back to the appropriate track and instructed the crew to contact the relevant Area Control Center.
The investigation
The ÚZPLN investigation examined radar records, audio recordings, and air traffic control documentation. The investigation reviewed the pre-flight communications between the crew and Clearance Delivery (CDD), as well as the actions taken by the controllers at both Delivery and Approach. The investigation also considered the operator's explanation, which claimed that the frequency assigned by Delivery differed from the published SID frequency by approximately 50 kHz, leading to the loss of contact as the aircraft's range increased.
Findings
- The crew's departure procedure was in direct conflict with the published and confirmed SID.
- The crew likely failed to conduct a proper pre-flight briefing, resulting in the deviation from the assigned route.
- The aircraft's radio equipment was functioning correctly, and communications were intelligible both before takeoff and after contact was re-established.
- Air traffic controllers responded correctly to the deviation and the lack of communication, attempting all available means to establish contact and providing corrective vectors once the aircraft responded.
- The incident was classified as a significant incident due to the aircraft's deviation from ATC clearance and the period of unresponsiveness.