ZNY CTLR CONCERNED WITH POSSIBLE OPERROR AT FL350 IN NON-RADAR CTLR.

Narrative

AT THE TIME OF THE POSSIBLE LOSS OF SEPARATION; I WAS PROVIDING TRAINING TO A DEVELOPMENTAL. WE WERE INITIALLY WORKING NORTH ATLANTIC SECTORS GEMINI AND MERCURY COMBINED; BUT WE DECIDED TO SPLIT THE SECTORS DUE TO HVY TFC VOLUME. WHILE WE WERE SPLITTING THE SECTORS; MONCTON CTR CALLED (LATE) WITH AN ESTIMATE THAT WAS APPROX 20 MINS FROM THE BOUNDARY. I HAND-COPIED THE ESTIMATE ON ACFT Y AS NO FLT DETAILS WERE IN OUR SYS. I DID NOT NOTICE THAT ACFT Y; WITH ROUTING JEBBY -- 4300N/05000W WAS POTENTIAL TFC FOR ACFT X WITH ROUTING 4200N/06000W 4300N/05500W 4400N/05000W. THESE FLTS CROSSED AT APPROX 5500W. ONCE ACFT Y WAS TYPED INTO THE SYS; THE DATA BLOCK APPEARED ON THE ODAPS DISPLAY 'FLASHING' WITH ACFT X INDICTING THAT A CONFLICT ALERT EXISTED. BASED UPON FLT STRIP TIMES/ESTIMATES; THE 2 ACFT WOULD HAVE ONLY HAD ABOUT 1 OR 2 MINS XING TIME AT 5500W AT THE SAME ALT (FL350). THEREFORE; AS SOON AS THE CONFLICT WAS DETECTED I CLBED ACFT X TO FL360 AND CALLED MONCTON CTR TO SEE IF THEY WERE STILL IN RADIO CONTACT WITH ACFT Y. MONCTON SAID THEY SWITCHED ACFT Y TO COMMERCIAL RADIO SO I REQUESTED CTL AND SUBSEQUENTLY DSNDED ACFT Y TO FL340. ACFT X RPTED LEVEL AT FL360 AND ACFT Y AT FL340 PRIOR TO THE POINT WHERE THEIR RTES OF FLT CROSSED. HOWEVER; I DO NOT KNOW IF MONCTON CTR HAD ACFT Y IN RADAR COVERAGE (WHERE ONLY 5 MI LATERAL SEPARATION WOULD BE REQUIRED) WHEN THE FLTS WERE AT THE SAME ALT. AND; SINCE I AM UNCERTAIN WHETHER THE FLTS HAD 60 NM LATERAL SEPARATION (NON-RADAR; MNPS) AT THE TIME VERT SEPARATION WAS ESTABLISHED AND OR 10 MINS CONVERGING AT 5500W; I WANTED TO RPT THIS INCIDENT AS A POSSIBLE LOSS OF SEPARATION. THIS INCIDENT MAY HAVE BEEN A NON-EVENT. NEITHER ACFT RPTED TFC (ON TCAS) AND NO ACTION; EVASIVE OR OTHERWISE; WAS TAKEN BY THE PLTS.