Narrative:

Air carrier X going to boston asked to increase speed to 300 KTS (from 270 KTS). Air carrier Y climbing off lga told to maintain 300 KTS or less. 3 mins later, at level flight, ground speed showed a difference of 40 KTS and the aircraft got within 4.75 mi of each other. Back aircraft turned 80 degrees to the north and then continued on course. Supplemental information from acn 199216. The problem should not have happened at all. 2 aircraft en route to the same fix. First one (air carrier X) level at FL210 and assigned 300 KTS. Air carrier Y climbing out of 170 for FL210 and well in trail of air carrier X (approximately 8 mi) given 300 KTS or less. Once speeds were forwarded to the next sector and the in trail was achieved, we went on to other business. Approximately 2-3 mins later, the next sector calls and asks for more room between those 2 aircraft before they take the handoff on the second one. At that time the first aircraft was showing 360 KTS on the ground speed and the second showing 420 KTS. Then the radar controller turned the #2 aircraft hard left, but separation was already lost (4.5 mi). I think that possibly the #2 aircraft was going a little faster than assigned. The speeds really should have worked. The occurrence was recognized at the sector first, then at the area supervisor's desk.

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Original NASA ASRS Text

Title: ACR Y NON ADHERENCE TO ATC CLRNC (SPD RESTRICTION) HAD LTSS FROM ACR X. SYS ERROR.

Narrative: ACR X GOING TO BOSTON ASKED TO INCREASE SPD TO 300 KTS (FROM 270 KTS). ACR Y CLBING OFF LGA TOLD TO MAINTAIN 300 KTS OR LESS. 3 MINS LATER, AT LEVEL FLT, GND SPD SHOWED A DIFFERENCE OF 40 KTS AND THE ACFT GOT WITHIN 4.75 MI OF EACH OTHER. BACK ACFT TURNED 80 DEGS TO THE N AND THEN CONTINUED ON COURSE. SUPPLEMENTAL INFO FROM ACN 199216. THE PROBLEM SHOULD NOT HAVE HAPPENED AT ALL. 2 ACFT ENRTE TO THE SAME FIX. FIRST ONE (ACR X) LEVEL AT FL210 AND ASSIGNED 300 KTS. ACR Y CLBING OUT OF 170 FOR FL210 AND WELL IN TRAIL OF ACR X (APPROX 8 MI) GIVEN 300 KTS OR LESS. ONCE SPDS WERE FORWARDED TO THE NEXT SECTOR AND THE IN TRAIL WAS ACHIEVED, WE WENT ON TO OTHER BUSINESS. APPROX 2-3 MINS LATER, THE NEXT SECTOR CALLS AND ASKS FOR MORE ROOM BTWN THOSE 2 ACFT BEFORE THEY TAKE THE HDOF ON THE SECOND ONE. AT THAT TIME THE FIRST ACFT WAS SHOWING 360 KTS ON THE GND SPD AND THE SECOND SHOWING 420 KTS. THEN THE RADAR CTLR TURNED THE #2 ACFT HARD L, BUT SEPARATION WAS ALREADY LOST (4.5 MI). I THINK THAT POSSIBLY THE #2 ACFT WAS GOING A LITTLE FASTER THAN ASSIGNED. THE SPDS REALLY SHOULD HAVE WORKED. THE OCCURRENCE WAS RECOGNIZED AT THE SECTOR FIRST, THEN AT THE AREA SUPVR'S DESK.

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.