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

Attributes
ACN	182492
Time
Date	199106
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : eau
State Reference	WI
Altitude	msl bound lower : 5000 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 10
ASRS Report	182492
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 24600 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Intra Facility Coordination Failure

Narrative:

Air carrier X at 6000 controller had control for lower reference mutual traffic small aircraft Y at 5000. Data block timed out on small aircraft Y and controller forgot about the aircraft. Descended air carrier X to 5000.

Original NASA ASRS Text

Title: ACR X HAD LTSS FROM SMA Y. SYS ERROR.

Narrative: ACR X AT 6000 CTLR HAD CTL FOR LOWER REFERENCE MUTUAL TFC SMA Y AT 5000. DATA BLOCK TIMED OUT ON SMA Y AND CTLR FORGOT ABOUT THE ACFT. DSNDED ACR X TO 5000.

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.