ZNY controller misjudges spacing and looses separation between 2 B737's.

Attributes
ACN	488165
Time
Date	200010
Day	Tue
Local Time Of Day	1201 To 1800
Place
State Reference	PA
Altitude	msl bound lower : 22000 msl bound upper : 23000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute : on vectors enroute airway : j75.airway
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737-500
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Route In Use	enroute airway : j48.airway
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 2.5 controller radar : 16 controller time certified in position1 : 14
ASRS Report	488165
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 29000 vertical : 600
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was vectored west, 250 degrees across J75 to allow air carrier Y inbound for bwi to descend. Air carrier X at FL220. Air carrier Y first cleared to FL250 for J48 traffic, once clear of J48, cleared to FL230 for air carrier X. After air carrier X was more than 6 mi from air carrier Y, I turned air carrier X back to a 210 degree heading to go behind air carrier Y, to rejoin J75. I then descended air carrier Y to FL180. When I got back to situation, the turn was not enough, responded more like a 230 degree heading. Air carrier X was heading for air carrier Y's j-ball. (J-ball or j-ring, 5 mi control ring that tracks along with a specified aircraft for range tracking for intended lateral separation sits.) air carrier Y was still showing FL230, so I asked speed, found that air carrier Y was only doing 270 KTS, asked air carrier Y to maintain 230. The pilot thought speed of 230 KTS. I had to correct air carrier Y to maintain FL230, he said he was through FL230, will come back up.

Original NASA ASRS Text

Title: ZNY CTLR MISJUDGES SPACING AND LOOSES SEPARATION BTWN 2 B737'S.

Narrative: ACR X WAS VECTORED W, 250 DEGS ACROSS J75 TO ALLOW ACR Y INBOUND FOR BWI TO DSND. ACR X AT FL220. ACR Y FIRST CLRED TO FL250 FOR J48 TFC, ONCE CLR OF J48, CLRED TO FL230 FOR ACR X. AFTER ACR X WAS MORE THAN 6 MI FROM ACR Y, I TURNED ACR X BACK TO A 210 DEG HDG TO GO BEHIND ACR Y, TO REJOIN J75. I THEN DSNDED ACR Y TO FL180. WHEN I GOT BACK TO SIT, THE TURN WAS NOT ENOUGH, RESPONDED MORE LIKE A 230 DEG HDG. ACR X WAS HEADING FOR ACR Y'S J-BALL. (J-BALL OR J-RING, 5 MI CTL RING THAT TRACKS ALONG WITH A SPECIFIED ACFT FOR RANGE TRACKING FOR INTENDED LATERAL SEPARATION SITS.) ACR Y WAS STILL SHOWING FL230, SO I ASKED SPD, FOUND THAT ACR Y WAS ONLY DOING 270 KTS, ASKED ACR Y TO MAINTAIN 230. THE PLT THOUGHT SPD OF 230 KTS. I HAD TO CORRECT ACR Y TO MAINTAIN FL230, HE SAID HE WAS THROUGH FL230, WILL COME BACK UP.

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.