ATC - Loss of separation - Curt Lewis

Incident: S7 A320 and Emirates B773 near Rostov on Jun 10th 2020, loss of separation A S7 Sibir Airlines Airbus A320-200, registration VQ-BPL performing flight S7-2126 from Rostov to Moscow Domodedovo (Russia), was cleared to climb and was climbing to FL380 northbound out of Rostov about 130nm northeast of Rostov. An Emirates Airlines Boeing 777-300, registration A6-EGQ performing flight EK-160 from Oslo (Norway) to Dubai (United Arab Emirates), was enroute at FL370 about 130nm northeast of Rostov southbound on the same airway. The sector north of Rostov was being controlled by a controller under training and a training controller. A controller in the adjacent sector noticed the dangerous approximation of the two aircraft and notified the training instructor. Only then the sector controller took action turning Emirates by 50 degrees to their right, having the Sibir Airlines descend to FL360 immediately and also turn 50 degrees to their right and further reiterating to accelerate the descent. While the aircraft already begin their instructed evasive actions, the controller desk activated a short term collision alert. According to ADS-B transmissions the A320 stopped their climb at 36775 feet and began to descend at 18:14:52Z, at that point the two aircraft were still on head on trajectories 22nm apart from each other. A minute later the aircraft reached their point of closest separation, the A320 was at 36700 feet, the horizontal separation had reduced to 6.5nm, both aircraft were already in their right turns onto diverging trajectories. The aircraft passed each other at a horizontal separation of about 3.8nm and 500 feet vertical separation, at 18:16:52Z the A320 was at 36050 feet, the horizontal separation had increased again to 13.2nm. Russia's Southern Transport Prosecution Office have initiated an investigation into the occurrence.