Air carrier X had less than standard separation with air carrier Y. System error.

Attributes
ACN	154758
Time
Date	199008
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cgt
State Reference	IL
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller non radar : 6 controller radar : 5
ASRS Report	154758
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 10800 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

I was the radar controller at the plant sector of ZAU. At that time I was working air carrier X wow inbound to ord. I turned him direct ord and descended him to 11000'. The pilot read back 10000' and came within 600' vertical and 18 mi horizontal. Callback conversation with reporter revealed the following: the reporter stated ca brought the conflict to his attention. He turned and climbed air carrier X but still had less than standard separation. Aircraft 2 was an air carrier medium large transport. Traffic was issued and air carrier X had air carrier Y in sight.

Original NASA ASRS Text

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

Narrative: I WAS THE RADAR CTLR AT THE PLANT SECTOR OF ZAU. AT THAT TIME I WAS WORKING ACR X WOW INBND TO ORD. I TURNED HIM DIRECT ORD AND DSNDED HIM TO 11000'. THE PLT READ BACK 10000' AND CAME WITHIN 600' VERT AND 18 MI HORIZ. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE RPTR STATED CA BROUGHT THE CONFLICT TO HIS ATTN. HE TURNED AND CLBED ACR X BUT STILL HAD LESS THAN STANDARD SEPARATION. ACFT 2 WAS AN ACR MLG. TFC WAS ISSUED AND ACR X HAD ACR Y IN SIGHT.

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.