What happened
On May 3, 2015, an air traffic management incident occurred within the Warsaw Flight Information Region (FIR EPWW) at a position approximately 40 NM from the TOMTI navigational waypoint. The event involved a Boeing 737-40 and an Airbus A320 operating within the GAT ACC sector.
The Boeing 737-400, flying from EPWA to LEMD, was maintaining flight level 320 along the TRZ - TOMTI route. The Airbus A320, traveling from UUEE to LKPR, was descending along the same route. Due to the higher speed of the A320, the aircraft closed the distance to the Boeing 737, eventually crossing the 737's flight level at a distance of only 6.6 NM, which failed to maintain the required minimum separation of 7 NM.
The investigation
The investigation examined the actions of the air traffic controllers and the coordination between sectors. It was established that the controller on duty held all necessary valid licenses and medical certifications. The investigation also reviewed the radar monitoring systems and the coordination between the Prague Radar controllers (directing aircraft into the Warsaw FIR) and the local ACC controllers.
Findings
- The controllers failed to coordinate a shortcut for the A320 toward waypoint PR532, an action that would have provided sufficient separation during the descent.
- The air traffic controller did not react to the "MC" (Minimum Collision) warning displayed on the radar indicator.
- The controller authorized the descent for the A320 crew without ensuring the aircraft were on parallel courses and without establishing a required rate of descent.
- The crew of the Boeing 737-400 received instructions to execute a left turn too late to prevent the separation loss.
- The primary cause of the incident was errors in air traffic management (ATM) performance.