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

Attributes
ACN	142532
Time
Date	199004
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 8300 flight time type : 2000
ASRS Report	142532
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12000 flight time type : 8000
ASRS Report	142195
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 1500 vertical : 200
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was being radar vectored by ord approach 119.0 on 180 degree heading, 4000' 170 KTS, as assigned when air carrier Y, medium large transport, passed from right to left in front of us. He was descending and at time of sighting, he was at our 1:30 position and about 200' above us. Advised ATC of this and he stated they should have passed behind us. No time to react as we were in and out of clouds. Supplemental information from acn 142195. I saw air carrier Y descend across our nose from right to left. His approximately heading was 090 degree.

Original NASA ASRS Text

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

Narrative: ACR X WAS BEING RADAR VECTORED BY ORD APCH 119.0 ON 180 DEG HDG, 4000' 170 KTS, AS ASSIGNED WHEN ACR Y, MLG, PASSED FROM R TO L IN FRONT OF US. HE WAS DSNDING AND AT TIME OF SIGHTING, HE WAS AT OUR 1:30 POS AND ABOUT 200' ABOVE US. ADVISED ATC OF THIS AND HE STATED THEY SHOULD HAVE PASSED BEHIND US. NO TIME TO REACT AS WE WERE IN AND OUT OF CLOUDS. SUPPLEMENTAL INFO FROM ACN 142195. I SAW ACR Y DSND ACROSS OUR NOSE FROM R TO L. HIS APPROX HDG WAS 090 DEG.

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.