What happened
On June 13, 2014, an incident occurred within the Warsaw ACC "T" sector involving three aircraft: an Embraer 190, a Boeing 737-800, and an Airbus A321. The Embraer 190 was performing a flight from EPWA to LFPG and was climbing toward a target cruise altitude of FL 360. At the same time, the Boeing 737-800 was cruising at FL 340 and the Airbus A321 was at FL 350.
To prevent a conflict, the air traffic controller initially instructed the Embraer 190 crew to maintain a vertical climb rate of 1000 feet per minute until reaching FL 360. While the controller issued a minor heading change to the Boeing 737-800 to manage the closing distance, the Embraer 190 pilot later informed the controller that maintaining the requested climb rate would not be possible. Following this, the controller instructed the Embraer 190 to turn right by 30 degrees and accelerate its climb to intercept FL 350, while simultaneously notifying the crew of the conflicting Boeing 737-800 traffic. During this sequence, the controller also instructed the Airbus A321 to turn right by 15 degrees.
As a result of these maneuvers, the minimum separation between the Embraer 190 and the Boeing 737-800 decreased to 6.7 NM horizontally and 700 ft vertically, failing to meet the required separation standards of 7 NM or 1000 ft.
The investigation
The PKBWL examined the communications and maneuvers performed by the air traffic controller and the flight crews involved. The investigation focused on the sequence of instructions issued during the climb phase and the management of the converging traffic within the ACC sector.