Air carrier X had less than standard separation from aircraft Y. System error.

Attributes
ACN	154476
Time
Date	199008
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : scy
State Reference	TX
Altitude	msl bound lower : 11000 msl bound upper : 11600
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9500 flight time type : 900
ASRS Report	154477
Person 2
Function	flight crew : single pilot
Qualification	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 : 6000 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

Air carrier X was given a very late clearance to cross scy 296 degree right/18 DME at 11000'. When asked if we could do that we replied that we would do our best. When passing through approximately 13000' we were handed off to the next controller. At approximately 12000' in a high rate of descent the controller very urgently requested we level off at 1200'. Immediate action was taken to stop the descent and return to 12000'. We then saw aircraft Y that appeared to be at 11000' approximately 1 mi away. We were still 2 DME short of our assigned crossing restriction.

Original NASA ASRS Text

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

Narrative: ACR X WAS GIVEN A VERY LATE CLRNC TO CROSS SCY 296 DEG R/18 DME AT 11000'. WHEN ASKED IF WE COULD DO THAT WE REPLIED THAT WE WOULD DO OUR BEST. WHEN PASSING THROUGH APPROX 13000' WE WERE HANDED OFF TO THE NEXT CTLR. AT APPROX 12000' IN A HIGH RATE OF DSNT THE CTLR VERY URGENTLY REQUESTED WE LEVEL OFF AT 1200'. IMMEDIATE ACTION WAS TAKEN TO STOP THE DSNT AND RETURN TO 12000'. WE THEN SAW ACFT Y THAT APPEARED TO BE AT 11000' APPROX 1 MI AWAY. WE WERE STILL 2 DME SHORT OF OUR ASSIGNED XING RESTRICTION.

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.