B767-300 and 300 ER
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 9
Confusion; Situational Awareness
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Weather
R19 was staffed with only an R-side controller; and the traffic was moderate and building. Rides were terrible and the frequency congestion because of such was high. The workload was moderately busy when an aircraft advised he was descending for traffic. I asked if the aircraft that called was Aircraft Y because I observed his altitude now FL380-FL377. The next transmission was from Aircraft X who informed me that he was descending for traffic above that had lost altitude. It all made sense now and I told Aircraft X that the traffic was passing laterally 2 miles and then questioned Aircraft Y to say altitude. Aircraft Y responded that he encountered 'mountain wave' and lost altitude. I informed the supervisor and the aircraft returned to their assigned altitudes. Weather phenomena led to the loss of separation.
A ZME Front Line Manager (FLM) reported of a loss of separation due to an aircraft getting a mountain wave and descending. The other aircraft first reported to ATC that they were descending for traffic.