N90 controller misjudges radar vectoring to establish separation between an SF34 and a LJ31.

Attributes
ACN	510256
Time
Date	200105
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hpn.airport
State Reference	NY
Altitude	msl bound lower : 6000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90.tracon artcc : zdv.artcc
Make Model Name	SF 340A
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : n90.tracon
Operator	general aviation : corporate
Make Model Name	Learjet 31
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Experience	controller military : 4 controller non radar : 6 controller radar : 27
ASRS Report	510256
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued advisory controller : issued new clearance
Consequence	faa : investigated
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working as departure controller at the new york TRACON, westbury, ny (lga area). Aircraft a (SF34) departed hpn runway 34. I climbed aircraft a to 11000 ft. Aircraft B (LR31) departed hun, was level at 6000 ft, heading 280 degrees. I turned aircraft B left 25 degrees. A short time later, I climbed aircraft B to 7000 ft. Aircraft a was issued a right 070 degree vector on course. My plan was to turn this aircraft a behind aircraft B. Aircraft a's turn was faster than I expected. At approximately 6 NM from aircraft B, I issued traffic (1 O'clock position) and turn left 360 degrees. Aircraft a did not see aircraft B. I then issued traffic to aircraft B (level at 7000 ft). Aircraft B had aircraft a in sight, 12 O'clock position, 3 mi. However, IFR separation was lost. Aircraft a was slow to turn. I also may have misjudged aircraft a's position with regards to aircraft B. I had time to stop climb of aircraft a. I did not. I could have climbed aircraft B, I did not.

Original NASA ASRS Text

Title: N90 CTLR MISJUDGES RADAR VECTORING TO ESTABLISH SEPARATION BTWN AN SF34 AND A LJ31.

Narrative: I WAS WORKING AS DEP CTLR AT THE NEW YORK TRACON, WESTBURY, NY (LGA AREA). ACFT A (SF34) DEPARTED HPN RWY 34. I CLBED ACFT A TO 11000 FT. ACFT B (LR31) DEPARTED HUN, WAS LEVEL AT 6000 FT, HDG 280 DEGS. I TURNED ACFT B L 25 DEGS. A SHORT TIME LATER, I CLBED ACFT B TO 7000 FT. ACFT A WAS ISSUED A R 070 DEG VECTOR ON COURSE. MY PLAN WAS TO TURN THIS ACFT A BEHIND ACFT B. ACFT A'S TURN WAS FASTER THAN I EXPECTED. AT APPROX 6 NM FROM ACFT B, I ISSUED TFC (1 O'CLOCK POS) AND TURN L 360 DEGS. ACFT A DID NOT SEE ACFT B. I THEN ISSUED TFC TO ACFT B (LEVEL AT 7000 FT). ACFT B HAD ACFT A IN SIGHT, 12 O'CLOCK POS, 3 MI. HOWEVER, IFR SEPARATION WAS LOST. ACFT A WAS SLOW TO TURN. I ALSO MAY HAVE MISJUDGED ACFT A'S POS WITH REGARDS TO ACFT B. I HAD TIME TO STOP CLB OF ACFT A. I DID NOT. I COULD HAVE CLBED ACFT B, I DID NOT.

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.