Air carrier Y issued visual approach clearance before sighting air carrier X. Less than standard sep...

Attributes
ACN	199180
Time
Date	199201
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	approach : straight in
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
ASRS Report	199180
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error
Situations
Navigational Aid	Unspecified

Narrative:

Air carrier X was turned onto final approach course runway 27R and cleared for visual approach, about 8-10 mi from runway. Air carrier Y was on right downwind runway 27R. Air carrier X radar track disappeared from radar scope and primary track became displaced south of runway 27R localizer. After completing xmissions to 3 or 4 other uninvolved aircraft (about 1 min), I turned air carrier Y to base, having lost track of and position on air carrier X. Air carrier Y reported airport in sight and was cleared for visual approach. Immediately thereafter I realized that something was amiss. I observed a very faint primary target just south of localizer, 12 O'clock and 2 mi from air carrier Y at this point air carrier Y asked if he was to follow 12 O'clock traffic to which I replied in the affirmative having realized that I had indeed lost track on air carrier X. Air carrier Y turned final to follow air carrier X and continued uneventfully to landing. I believe my vigilance was disrupted due to complete loss of radar tracking on an aircraft under my control. This problem has been a continuous one, reported daily by controllers at O'hare. It occurs in several quadrants on the radar display a varying altitudes. Our considerable workload is greatly increased due to effort required to provide extra vigilance for fear of 'losing' an aircraft during sequencing for approach. Working with this flawed system causes great anxiety and frustration. I believe such a problem requires immediate and extensive attention.

Original NASA ASRS Text

Title: ACR Y ISSUED VISUAL APCH CLRNC BEFORE SIGHTING ACR X. LTSS. SYS ERROR. SITUATION: ATC EQUIP PROBLEM RADAR NON DETECTION OF ACFT BY TRACON RADAR RADAR TRACKING.

Narrative: ACR X WAS TURNED ONTO FINAL APCH COURSE RWY 27R AND CLRED FOR VISUAL APCH, ABOUT 8-10 MI FROM RWY. ACR Y WAS ON R DOWNWIND RWY 27R. ACR X RADAR TRACK DISAPPEARED FROM RADAR SCOPE AND PRIMARY TRACK BECAME DISPLACED S OF RWY 27R LOC. AFTER COMPLETING XMISSIONS TO 3 OR 4 OTHER UNINVOLVED ACFT (ABOUT 1 MIN), I TURNED ACR Y TO BASE, HAVING LOST TRACK OF AND POS ON ACR X. ACR Y RPTED ARPT IN SIGHT AND WAS CLRED FOR VISUAL APCH. IMMEDIATELY THEREAFTER I REALIZED THAT SOMETHING WAS AMISS. I OBSERVED A VERY FAINT PRIMARY TARGET JUST S OF LOC, 12 O'CLOCK AND 2 MI FROM ACR Y AT THIS POINT ACR Y ASKED IF HE WAS TO FOLLOW 12 O'CLOCK TFC TO WHICH I REPLIED IN THE AFFIRMATIVE HAVING REALIZED THAT I HAD INDEED LOST TRACK ON ACR X. ACR Y TURNED FINAL TO FOLLOW ACR X AND CONTINUED UNEVENTFULLY TO LNDG. I BELIEVE MY VIGILANCE WAS DISRUPTED DUE TO COMPLETE LOSS OF RADAR TRACKING ON AN ACFT UNDER MY CTL. THIS PROBLEM HAS BEEN A CONTINUOUS ONE, RPTED DAILY BY CTLRS AT O'HARE. IT OCCURS IN SEVERAL QUADRANTS ON THE RADAR DISPLAY A VARYING ALTS. OUR CONSIDERABLE WORKLOAD IS GREATLY INCREASED DUE TO EFFORT REQUIRED TO PROVIDE EXTRA VIGILANCE FOR FEAR OF 'LOSING' AN ACFT DURING SEQUENCING FOR APCH. WORKING WITH THIS FLAWED SYS CAUSES GREAT ANXIETY AND FRUSTRATION. I BELIEVE SUCH A PROBLEM REQUIRES IMMEDIATE AND EXTENSIVE ATTN.

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.

Air carrier Y issued visual approach clearance before sighting air carrier X. Less than standard separation. System error. Situation: ATC equipment problem radar non detection of aircraft by TRACON radar radar tracking.