What happened
On November 1, 2007, at 12:15 UTC, a near-collision incident occurred approximately 1 km from runway 06 at Přerov Airport (LKPO). The event involved a military Mi-24V helicopter operated by the Czech Army and a Z 43 light aircraft, registration OK-KOS, operated by a private individual.
During a period of mixed traffic, the Z 43 was entering the airport traffic pattern. The air traffic controller (TWR EC) provided the pilot with incomplete traffic information regarding an approaching helicopter. Although the pilot of the Z 43 provided an incorrect read-back regarding his intentions, the controller did not correct the error. Furthermore, when the pilot reported having visual contact with other traffic, the controller accepted this as confirmation that sufficient separation was being maintained.
As the Mi-24V was on final approach, the Z 43 crossed its trajectory from the right. The aircraft came within approximately 150 m of the helicopter. The instructor on board the Mi-24V identified the danger and immediately ordered an evasive maneuver. Both aircraft subsequently landed safely.
The investigation
The ÚZPLN investigation examined radar records, audio recordings, and flight data from the helicopter. The investigation focused on the coordination between the Tower (TWR EC) and the Precision Approach Radar (PAR EC) controllers, as well as the communication between the controllers and the pilots. The investigation established that the controllers lacked radar identification for the Z 43 at the critical moment, as the aircraft was only detected by the PAR system when it was 1 km from the touchdown point.
Findings
- The air traffic controllers failed to adequately assess the traffic situation when communicating separation requirements between aircraft on different frequencies.
- The controller provided incomplete traffic information to the pilot of the Z 43.
- Non-standard phraseology was used by both the pilot of the Z 43 and the air traffic controller.
- The controller incorrectly assumed that the pilot of the Z 43 was maintaining separation based on the pilot's erroneous report of visual contact.
- The pilot of the Z 43 reached an incorrect conclusion that the approach path was clear, leading to the loss of separation.
- The coordination between TWR EC and PAR EC underestimated the risks posed by the pilot's non-standard responses.