2018 Warsaw Air Traffic Incident Involving LOT Polish Airlines Flights

Incident Overview and Aircraft Involved On March 1, 2018, an air traffic incident was recorded in the Warsaw Terminal Maneuvering Area (TMA EPWA). The event involved two Embraer E170 aircraft and one Boeing 737-800. The investigation was conducted by the user operator, with the supervising investigator identified as Piotr Richter. The investigation concluded on September 11, 2018, and resulted in an incident report rather than a formal safety recommendation. ## Sequence of Events The incident involved LOT7005, an E170 departing from runway 29 at EPWA, and LOT268, a B737-800 arriving from EHAM. At 20:31:39, the approach controller connected both aircraft with a radar beam line, noting a distance of 15.8 nautical miles and a predicted minimum separation of 4.75 nautical miles. Shortly after, LOT7005 received instructions to maintain its current course to establish radar separation. At 20:32:09, LOT268 was cleared to descend to 7,000 feet AMSL, while at 20:32:43, LOT7005 was cleared to climb to FL240. At this moment, a yellow STCA prediction alarm was displayed, with the predicted separation decreasing to 3.64 nautical miles. By 20:33:20, LOT7005 was instructed to turn right to heading 275° to maintain separation. The distance between the aircraft was 5.5 nautical miles, with a predicted minimum separation of 2.99 nautical miles. LOT7005 remained approximately 2,000 feet below the conflicting traffic. At 20:33:47, the minimum distance between LOT7005 and LOT268 reached 3.3 nautical miles, with LOT7005 still 1,200 feet below. The controller instructed LOT7005 to fly straight to waypoint KUKAM. At 20:33:56, a red STCA violation alarm was displayed, with the separation at 3.7 nautical miles and 600 feet. ## Contributing Factors and Resolution The investigation identified a delay in the crew's execution of ATC instructions as the primary cause of the incident. Contributing circumstances included repeated readbacks and multiple overlapping transmissions from two transmitting stations. The crew of LOT7005 requested confirmation of the instruction to fly straight to KUKAM, which the controller confirmed. However, the pilot flying did not hear the transmission, requiring the instruction to be repeated. This led to multiple overlapping transmissions, delaying the expected maneuver by approximately 42 seconds. The controller had sufficient time to issue alternative instructions and continued to manage other traffic in the area effectively. The weather conditions on the day did not influence the incident. ## Preventive Actions The Director of the Operational Preparation Office was tasked with ensuring that future updates to the P_21 system or the new ATM system would allow STCA activation thresholds to be defined according to actual ATC procedures, such as 3 nautical miles at a distance of 16 nautical miles from the radar antenna.