Loss of Separation Between Boeing 737-800 and Airbus A319 in Warsaw FIR

Incident Overview

On June 13, 2015, an incident involving a Boeing 737-800 (B738) and an Airbus A319 (A319) occurred in the Warsaw Flight Information Region (EPWW). The two aircraft were on intersecting courses, leading to a loss of minimum vertical separation. The B738 was climbing to Flight Level (FL) 380 heading to waypoint OGSEN, while the A319 was at FL 370 on route LAGAR-POLON-RUDKA. The minimum required vertical separation of 1000 ft was not maintained, as the aircraft passed with a difference of 700 ft.

Sequence of Events

• At 20:43:55, the B738 crew reported passing FL260 climbing to FL360 and requested clearance to FL380, which was granted by the air traffic controller (ATC). Radar vectors indicated a collision course with the A319.
• At 20:47:15, the A319 crew reported at FL370 and requested a turn to a heading of 130 degrees to avoid clouds. The ATC approved the turn.
• At 20:48:30, radar showed the distance between the A319 and B738 (call sign WZZ5JH) at FL360 (requested FL370).
• At 20:51:45, the B738 received clearance to fly direct to OGSEN, reducing distance to the A319.
• At 20:52:05, a yellow STCA alert appeared as the B738 passed through FL374.
• At 20:52:15, the B738 was instructed to expedite climb to FL380.
• At 20:52:20, a red STCA alert appeared as the B738 passed FL376.
• At 20:52:55, radar echoes of both aircraft overlapped.

Findings

• The controller was on his first shift after three days off.
• The number of open sectors was adequate, but traffic density was at the upper limit.
• The controller held a valid Air Traffic Controller license with ACS endorsement obtained in 2015, and his medical certificate and refresher training (last in 2013) were current.
• The B738 was cleared to climb to FL380 while on a collision course with the A319 at FL370.
• Increased radio transmissions due to weather avoidance in the sector.
• The controller focused attention on non-conflicting aircraft instead of the climbing B738.
• The MTCD warning system was switched off.

Probable Cause

The probable cause of the incident was errors in air traffic management (ATM).

Preventive Actions

The investigating body recommended: 1. Providing the final report to the ACC GAT LSM to inform the involved controller and reduce recurrence. 2. Incorporating the report and materials into the ATS training center's database for use in basic and refresher training.

No safety recommendations were issued by the commission.