What happened
On March 3, 2019, at 12:13 UTC, a serious near-collision occurred at Letňany Airport (LKLT) involving a Bristell ELSA, registration OK-WAR 18, and a Cessna 172S, registration OK-COK.
The pilot of the Bristell ELSA was arriving from Ústí nad Labem and had requested a direct approach to the airport. While the AFIS dispatcher instructed the pilot to join the circuit for runway 05R, the pilot did not specify a particular entry point. During the approach, the pilot changed course, heading toward the area between the first and second circuit legs.
Simultaneously, a Cessna 172S carrying an instructor and a student pilot was performing circuit maneuvers. The two aircraft's trajectories intersected at a high relative speed of approximately 150 kt. At 12:13:23, the Bristell ELSA passed approximately 75 meters in front of the Cessna 172S with a vertical separation of only about 125 ft. The student pilot in the Cessna 172S spotted the aircraft passing underneath them, prompting the instructor to declare the emergency and perform a 360-degree turn to establish separation.
The investigation
The ÚZPLN investigation examined the flight paths, radio communications, and pilot statements. The investigation established that the Bristell ELSA pilot entered the circuit area in a manner that crossed the established traffic pattern. The pilot noted that the sun's position hindered visibility and that they had failed to request specific arrival information or report their intended entry point more clearly.
Regarding the Cessna 172S, the instructor was conducting training maneuvers. The investigation found that the AFIS dispatcher could not see the Bristell ELSA from the tower and therefore did not issue any traffic warnings. Neither aircraft was equipped with electronic collision avoidance technology, such as FLARM.
Findings
- The primary causes of the incident were improper arrival procedures and the late detection of a potential collision.
- The pilot of the Bristell ELSA did not report their intended circuit entry point, resulting in a flight path that intersected the existing traffic.
- Visual scanning by the Bristell ELSA pilot was compromised by the position of the sun.
- The AFIS dispatcher was unable to identify the approaching threat and did not issue a warning.
- The aircraft were flying with a vertical separation of only 125 ft at the moment of closest approach.