Narrative:

Traffic vol and complexity were both high. The sector is a non radar oceanic control sector in international airspace. Traffic heavy both north and southbound with crossing traffic climbing. Aircraft X was northbound on A300 at FL280, estimating the champ intersection at XA03Z. Aircraft Y southbound cleared direct to champ intersection was offered options of FL270 on A300 or FL330 via rerte. Aircraft Y accepted FL270 on a 300. Flight strip for aircraft Y indicated champ intersection time of XA05Z. After recoord with the next sector's approval, assigned aircraft Y FL280. I had mistakenly believed that aircraft X northbound had already cleared my airspace when in fact it had not been radar idented at the next sector. Notification of the incident came from the pilot of aircraft X requesting identify of traffic at his altitude. Neither aircraft were in radar coverage at the moment of the incident. Contributing factors include poor flow control, 5 north.Y. Departures mixing with overflts entering airspace within 15 mins, traffic complexity, crossing traffic needing climb clrncs and time revisions on overflts necessitating altitude change, and lack of a visibility display of the non radar sectors and lack of C/a. Supplemental information from acn 139066: after departure from sju, we were assigned FL280 by sju departure control as our final altitude. Less than 1 min after crossing champ at FL280, and at XA03Z, an aircraft passed southbound approximately 1500' to our east at what appeared to be our altitude. When we questioned ZNY as to the altitude of the aircraft, we were informed it was air carrier Y at FL280. Supplemental information from acn 129359: we were cleared to sju. We were level at FL280. Approaching champ north.Y. Pointed out traffic. It was at this time we heard additional traffic check in at FL280 and realized that there could be a conflict. Before we had a chance to question north.Y. We observed traffic going past our 1:30-2 O'clock position approximately 1/4 mi away. I believe both crew realized what happened and notified north.Y. North.Y. Agreed and told us that a report would be filed. When we landed at sju we notified our company and filed at report to the chief pilot.

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Original NASA ASRS Text

Title: ACR WAS ASSIGNED SAME ALT AS OPPOSITE DIRECTION TRAFFIC ON SAME ROUTE OVER OCEAN.

Narrative: TFC VOL AND COMPLEXITY WERE BOTH HIGH. THE SECTOR IS A NON RADAR OCEANIC CTL SECTOR IN INTL AIRSPACE. TFC HEAVY BOTH N AND SBND WITH XING TFC CLBING. ACFT X WAS NBOUND ON A300 AT FL280, ESTIMATING THE CHAMP INTXN AT XA03Z. ACFT Y SBND CLRED DIRECT TO CHAMP INTXN WAS OFFERED OPTIONS OF FL270 ON A300 OR FL330 VIA RERTE. ACFT Y ACCEPTED FL270 ON A 300. FLT STRIP FOR ACFT Y INDICATED CHAMP INTXN TIME OF XA05Z. AFTER RECOORD WITH THE NEXT SECTOR'S APPROVAL, ASSIGNED ACFT Y FL280. I HAD MISTAKENLY BELIEVED THAT ACFT X NBOUND HAD ALREADY CLRED MY AIRSPACE WHEN IN FACT IT HAD NOT BEEN RADAR IDENTED AT THE NEXT SECTOR. NOTIFICATION OF THE INCIDENT CAME FROM THE PLT OF ACFT X REQUESTING IDENT OF TFC AT HIS ALT. NEITHER ACFT WERE IN RADAR COVERAGE AT THE MOMENT OF THE INCIDENT. CONTRIBUTING FACTORS INCLUDE POOR FLOW CTL, 5 N.Y. DEPS MIXING WITH OVERFLTS ENTERING AIRSPACE WITHIN 15 MINS, TFC COMPLEXITY, XING TFC NEEDING CLB CLRNCS AND TIME REVISIONS ON OVERFLTS NECESSITATING ALT CHANGE, AND LACK OF A VIS DISPLAY OF THE NON RADAR SECTORS AND LACK OF C/A. SUPPLEMENTAL INFO FROM ACN 139066: AFTER DEP FROM SJU, WE WERE ASSIGNED FL280 BY SJU DEP CTL AS OUR FINAL ALT. LESS THAN 1 MIN AFTER XING CHAMP AT FL280, AND AT XA03Z, AN ACFT PASSED SBND APPROX 1500' TO OUR E AT WHAT APPEARED TO BE OUR ALT. WHEN WE QUESTIONED ZNY AS TO THE ALT OF THE ACFT, WE WERE INFORMED IT WAS ACR Y AT FL280. SUPPLEMENTAL INFO FROM ACN 129359: WE WERE CLRED TO SJU. WE WERE LEVEL AT FL280. APCHING CHAMP N.Y. POINTED OUT TFC. IT WAS AT THIS TIME WE HEARD ADDITIONAL TFC CHK IN AT FL280 AND REALIZED THAT THERE COULD BE A CONFLICT. BEFORE WE HAD A CHANCE TO QUESTION N.Y. WE OBSERVED TFC GOING PAST OUR 1:30-2 O'CLOCK POS APPROX 1/4 MI AWAY. I BELIEVE BOTH CREW REALIZED WHAT HAPPENED AND NOTIFIED N.Y. N.Y. AGREED AND TOLD US THAT A RPT WOULD BE FILED. WHEN WE LANDED AT SJU WE NOTIFIED OUR COMPANY AND FILED AT RPT TO THE CHIEF PLT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.