Event Summary
On 10 April 2018, at 17:05 UTC, a serious incident involving a potential collision occurred between two aircraft during landing at Letňany Airport (LKLT). The aircraft were a Cessna 152, registration OK-HAD, operated by Flying Academy s.r.o., and a Bristell ELSA, registration OK-WAR 18, owned by Aeroklub Letňany. The incident took place approximately 0.9 km before the threshold of Runway 23L, at a height of about 50 m above ground level (AGL). Both aircraft completed the flight without damage.
Sequence of Events
OK-HAD departed LKLT at 15:41 UTC, followed by OK-WAR 18 at 16:35 UTC. Both aircraft left the vicinity of the airport and conducted VFR flights outside the Kbely Military CTR. At 16:54, the AFIS controller noted communication between the two aircraft on the Kbely tower frequency. Both were heading to the MIKE point in the Kbely CTR. OK-WAR 18 was advised of preceding traffic at 10 o'clock, 2 NM away, which the pilot confirmed in sight.
At 16:55:32, OK-WAR 18 contacted LKLT AFIS and was instructed to proceed via MIKE to LKLT, not above 2000 ft on QNH 1005 hPa, and approach Runway 23. At 16:56:29, the pilot of OK-HAD contacted AFIS in English and received similar instructions. OK-HAD, initially left of and ahead of OK-WAR 18, significantly altered its trajectory by about 70° to the right, crossing in front of OK-WAR 18 with a lateral separation of 0.85 NM, and ended up about 1.5 NM to the right and abeam of OK-WAR 18.
OK-HAD then turned left to a heading of approximately 185°, returning toward LKLT. This change placed OK-WAR 18 ahead of OK-HAD. At 17:00:40, the pilot of OK-WAR 18 reported being at Vinoř and on long final for Runway 23R. AFIS advised him he was number one and gave wind information. At 17:01:17, the pilot of OK-HAD reported approaching final for Runway 23L, located about 0.5 NM behind OK-WAR 18.
AFIS instructed OK-HAD to continue approach for Runway 23L and warned of traffic ahead proceeding to Runway 23R. The pilot of OK-HAD initially acknowledged incorrectly as Runway 23R, but after correction confirmed Runway 23L and traffic in sight. At that time, OK-HAD was flying at 100 kt, about 0.2 NM behind OK-WAR 18 and about 350 ft lower, while OK-WAR 18 was at 70 kt.
Near Collision
Due to poor viewing conditions, the AFIS controller left the station to visually confirm OK-HAD's position but could not see it. At 17:02:15, 0.9 km before the threshold of Runway 23L, OK-HAD (100 kt) passed from the left to a position below OK-WAR 18 (60 kt) and underflew it to the right. The vertical separation was approximately 10-15 m.
Pilot Statements
The pilot of OK-WAR 18 stated that during the final approach at about 50 m AGL, he saw the Cessna below him slightly to the right of the Runway 23R centerline. He immediately turned left toward Runway 23L and landed there. He estimated the vertical separation during the underfly at 15-20 m. Another person on board OK-WAR 18 reported seeing the Cessna directly below, about 10-20 m from their landing gear.
The pilot of OK-HAD reported that after contacting LKLT AFIS and being assigned Runway 23, she configured for landing. She stated that at the last moment she noticed traffic above and landed to the right of Runway 23R, outside the marked runway. After landing, she overran the runway end by about 100 m.
Conclusion
The incident was reported to the Czech Accident Investigation Institute (ÚZPLN) on 11 April 2018. The investigation determined that a potential collision occurred as a result of OK-HAD approaching from behind at a speed approximately 40 kt higher than OK-WAR 18, resulting in close proximity. No probable cause was formally stated.