Light transport X had less than standard separation from aircraft Y. System error.

Attributes
ACN	166029
Time
Date	199012
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pwl
State Reference	NY
Altitude	msl bound lower : 6000 msl bound upper : 6000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90 tower : psc
Operator	other
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 6000 flight time type : 1100
ASRS Report	166029
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

While in IMC conditions on V44 over pawling new york at 12000' MSL light transport X was told to descend to 7000' and to expedite the descent. At about 9000' we were told to descend to 6000' and to turn right to a heading of 245 degree (or maybe it was 275 degree I don't recall now). My copilot read back the descent to 6000' and asked for clarification of the heading. The controller acknowledged our readback and repeated the heading. Anyway, we were level, on the assigned heading for a couple of mins when the controller asked that we confirm our altitude. We replied 6000'. The controller then said we had been cleared to 7000' and gave us an immediate left turn to 090 degree heading and a climb to 7000'. The controller said aircraft X was at the same altitude within 2 mi. We never saw the other aircraft because we were IMC. The cause of this incident was the controllers confusion between us and an aircraft with a similar call sign. Apparently the descent to 6000' was meant for the other aircraft, but he used our call sign, acknowledged our readback, and even clarified the instructions when we requested it.

Original NASA ASRS Text

Title: LTT X HAD LESS THAN STANDARD SEPARATION FROM ACFT Y. SYSTEM ERROR.

Narrative: WHILE IN IMC CONDITIONS ON V44 OVER PAWLING NEW YORK AT 12000' MSL LTT X WAS TOLD TO DSND TO 7000' AND TO EXPEDITE THE DSNT. AT ABOUT 9000' WE WERE TOLD TO DSND TO 6000' AND TO TURN R TO A HDG OF 245 DEG (OR MAYBE IT WAS 275 DEG I DON'T RECALL NOW). MY COPLT READ BACK THE DSNT TO 6000' AND ASKED FOR CLARIFICATION OF THE HDG. THE CTLR ACKNOWLEDGED OUR READBACK AND REPEATED THE HDG. ANYWAY, WE WERE LEVEL, ON THE ASSIGNED HDG FOR A COUPLE OF MINS WHEN THE CTLR ASKED THAT WE CONFIRM OUR ALT. WE REPLIED 6000'. THE CTLR THEN SAID WE HAD BEEN CLRED TO 7000' AND GAVE US AN IMMEDIATE L TURN TO 090 DEG HDG AND A CLB TO 7000'. THE CTLR SAID ACFT X WAS AT THE SAME ALT WITHIN 2 MI. WE NEVER SAW THE OTHER ACFT BECAUSE WE WERE IMC. THE CAUSE OF THIS INCIDENT WAS THE CTLRS CONFUSION BTWN US AND AN ACFT WITH A SIMILAR CALL SIGN. APPARENTLY THE DSNT TO 6000' WAS MEANT FOR THE OTHER ACFT, BUT HE USED OUR CALL SIGN, ACKNOWLEDGED OUR READBACK, AND EVEN CLARIFIED THE INSTRUCTIONS WHEN WE REQUESTED IT.

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.