Narrative:

Both air carrier X and cga Y were en route to lga. Cga Y was doing .72 mach, and air carrier X 17 mi behind doing .83. Intrail restriction for ZNY was 20 mi for lga. With only 50 mi to boundary, the intrail restriction would not be made with cga Y in front. It was decided to vector him to the north, and let air carrier X pass to the south of him, and then vector back in behind. When cga Y made his turn north, his ground speed dropped off 80 KTS, making the overtake 220 KTS. Traffic was heavy in the sector with new york metropolitan area departures climbing wbound. Overflt traffic also diverted my attention momentarily. When I could get back to cga Y and air carrier X, separation was 6 mi. Cga Y was turned to a 150 degree, and air carrier X was given a 070 degree and descent clearance to FL310. Separation was lost at 4 mi and 800'. There were 11 aircraft on frequency at the time of the error plus 4 other data blocks, making a total of 15 data blocks in the sector. Altitude separation should have been effected prior to giving a turn to cga Y due to the speed differential. It could have been avoided if the associate radar controller was more attentive to his priority of duties, or the area traffic manager keeping a watch on the sector for potential conflicts due to the volume of aircraft being worked at the time.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR OVERTOOK PRECEDING IFR ACFT RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: BOTH ACR X AND CGA Y WERE ENRTE TO LGA. CGA Y WAS DOING .72 MACH, AND ACR X 17 MI BEHIND DOING .83. INTRAIL RESTRICTION FOR ZNY WAS 20 MI FOR LGA. WITH ONLY 50 MI TO BOUNDARY, THE INTRAIL RESTRICTION WOULD NOT BE MADE WITH CGA Y IN FRONT. IT WAS DECIDED TO VECTOR HIM TO THE N, AND LET ACR X PASS TO THE S OF HIM, AND THEN VECTOR BACK IN BEHIND. WHEN CGA Y MADE HIS TURN N, HIS GND SPEED DROPPED OFF 80 KTS, MAKING THE OVERTAKE 220 KTS. TFC WAS HEAVY IN THE SECTOR WITH NEW YORK METRO AREA DEPS CLIMBING WBOUND. OVERFLT TFC ALSO DIVERTED MY ATTN MOMENTARILY. WHEN I COULD GET BACK TO CGA Y AND ACR X, SEPARATION WAS 6 MI. CGA Y WAS TURNED TO A 150 DEG, AND ACR X WAS GIVEN A 070 DEG AND DSCNT CLRNC TO FL310. SEPARATION WAS LOST AT 4 MI AND 800'. THERE WERE 11 ACFT ON FREQ AT THE TIME OF THE ERROR PLUS 4 OTHER DATA BLOCKS, MAKING A TOTAL OF 15 DATA BLOCKS IN THE SECTOR. ALT SEPARATION SHOULD HAVE BEEN EFFECTED PRIOR TO GIVING A TURN TO CGA Y DUE TO THE SPEED DIFFERENTIAL. IT COULD HAVE BEEN AVOIDED IF THE ASSOCIATE RADAR CTLR WAS MORE ATTENTIVE TO HIS PRIORITY OF DUTIES, OR THE AREA TFC MGR KEEPING A WATCH ON THE SECTOR FOR POTENTIAL CONFLICTS DUE TO THE VOLUME OF ACFT BEING WORKED AT THE TIME.

Data retrieved from NASA's ASRS site as of August 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.