Light Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 5
Communication Breakdown; Confusion; Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Human Factors; Procedure
Aircraft X was coordinated inbound with SJU Center at FL340 his altitude options were FL340 or FL390 and they chose FL340 initially; then called and re-coordinated him at FL390; then called back and asked to coordinate him at FL370 climbing to FL390 which I approved reference the Aircraft Y at FL370 which was already coordinated from myself to SJU Center.A minute or two later I received a message from ARINC that the Aircraft X that he was responding to a TCAS alert which he said was 150 feet; not sure if it was above or below him. Not sure what to recommend.
ZNY Controller reports of an NMAC due to poor coordination of altitudes between two aircraft and possibly a slow climbing aircraft.