Incident Overview
On 3 May 2015, a loss of separation occurred between two aircraft in the Warsaw Flight Information Region (FIR EPWW), approximately 40 nautical miles from the TOMTI waypoint. The aircraft involved were a Boeing 737-400 (B734) and an Airbus A320 (A320). The B734 was en route from Warsaw to Madrid at flight level (FL) 320, following a route via TRZ and TOMTI. The A320, flying from Moscow to Prague, was descending to Prague behind the B734 along the same route. The A320 was faster and caught up to the B734, crossing its flight level at a distance of 6.6 NM, below the required minimum separation of 7 NM.
Circumstances
The incident occurred during the third shift of the air traffic controller after two days off. The number of open sectors was appropriate, and traffic volume was moderate. The controller, who had held an area control surveillance (ACS) license since 1992, possessed valid ratings and medical certificates. The controller's last refresher training had taken place from 21 to 28 October 2013.
Investigation Findings
The investigation identified several elements contributing to the incident. The controllers did not coordinate a shortcut for the A320 to fly direct to waypoint PR532, which would have allowed the aircraft to separate during the descent. Controllers from PRAHA RADAR had been routing aircraft directly into the Warsaw FIR. Additionally, the controller did not react to an "MC" warning displayed on the radar screen. The controller instructed the A320 crew to descend without first stabilizing the aircraft on parallel courses and without imposing a rate of descent (ROD). The B734 crew received a turn-left instruction too late.
Cause
The cause of the incident was errors in air traffic management (ATM) work.
Safety Actions
The investigating entity took the following preventive actions:
- The final report and collected materials were to be forwarded to the OJT Training Team of Area Control for presentation during training and to improve controller performance.
- The final report was to be provided to the LSM ACC GAT to brief the controller involved on the findings, aiming to reduce the likelihood of similar occurrences.
- The final report and materials were to be sent to the ATS Personnel Training Centre for inclusion in a database of investigated events used by instructors during initial and refresher training for air traffic controllers.
No safety recommendations were issued.