POTENTIAL CONFLICT.

Narrative

AS WE PROCEEDED NBOUND ON J-121 TOWARD SIE; NE; 114.8; AT FL290 AT 250 KTS; OUR RADAR SHOWED SOME WX AHEAD IN THE VICINITY OF SIE. THIS WAS VISUALLY CONFIRMED. TO GET AROUND THE UPWIND SIDE OF THE WX WE REQUESTED DEV TO THE W; BUT ATC ADVISED DEV E INSTEAD; SO WE FLEW ON THE EWARD SIDE OF THE WX. WHEN WE WERE APPROX ABEAM SIE TO THE E; HDG APPROX 050 DEGS ATC ASKED IF WE COULD COME TO A 300 DEG HDG. THE CAPT REPLIED 'I'D RATHER CONTINUE STRAIGHT AHEAD.' (WE WERE VMC IN SMOOTH AIR BENEATH THE OVERHANG). ATC RESPONDED 'CONTINUE STRAIGHT AHEAD.' SHORTLY AFTERWARD; WE WERE ASSIGNED A DSCNT TO FL280; WE GOT A TCASII RA THAT COMMANDED A GREEN AREA DSCNT AT 2000 FPM. WE INCREASED OUR RATE OF DSCNT FROM 1500 TO 2000 FPM; THEN LEVELED AT FL270. THE CTR CTLR SPOKE TO US AT THIS TIME; SAYING; 'CALLSIGN; I SEE YOU'RE LEVEL FL270.' WE RESPONDED; 'YES; FL270.' OFF TO THE L ABOUT 3 NM; AT ABOUT 10 O'CLOCK; I SAW AN AIRLINER ON AN OPPOSING HDG IN A CLOCKWISE TURN AWAY FROM OUR POS. THAT ACFT APPARENTLY MADE THE RADIO XMISSION HEARD SUBSEQUENTLY THAT INDICATED THAT IT'S PLT HAD RECEIVED A TCASII ADVISORY. NY CTR ASKED IF WE HAD BEEN INSTRUCTED TO HOLD AT SIE. WE REPLIED THAT WE HAD NOT. CTR THEN VECTORED US; BASICALLY; ON A R 360 DEG TURN AND DSCNT ON THE CAMRY ARR TO JFK. BEFORE WE LEFT NY ATC FREQ; THE CTLR THANKED US FOR OUR COMPLIANCE. NO OTHER COMMENTS WERE ADDRESSED TO US; AND THE REST OF THE FLT WAS UNEVENTFUL. OPINION REGARDING WHAT CAUSED THE PROBLEM: IT APPEARS THAT ATC TEMPORARILY LOST TRACK OF OUR POS AND/OR ALT AND ALLOWED US TO FLY IN THE VICINITY OF THE OTHER ACFT. OTHER: TCASII WORKS! SUPPLEMENTAL INFO FROM ACN 220264. PASSING FL280 IN DSCNT WE GOT A RA ON THE TCASII TO INCREASE DSCNT TO 2000 FPM; WHICH WE DID UNTIL 'CLR OF CONFLICT' AND LEVELED AT FL270. THE TFC PASSED ABOUT 3 MI TO OUR L AT FL280. THE TFC WAS POSSIBLY IN A HOLDING PATTERN AT BOTON INTXN (N OF SIE) AT FL280.