Radar tracking problem at ord causes targets to go into coast status on downwind.

Attributes
ACN	197037
Time
Date	199112
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : ord tower : sea
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Route In Use	approach : visual arrival other
Person 1
Affiliation	government : faa
Function	controller : approach
Experience	controller radar : 8
ASRS Report	197037
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other
Situations
ATC Facility	other physical facility

Narrative:

The beacon tracking system at O'hare has become unsatisfactory during certain times of the day. While running parallel visual approachs to 27L and 27R, 100 percent of the IFR targets went into coast status on downwind, base and intermittently on final. It was the worst I have seen in recent months. Without tracking data, the controller had no idea of aircraft altitude and airspeed. Having to ask pilots their altitude and speed 4 or 5 times while on the approach increased the controller's workload to a very unsafe level. Earlier during the shift, the tracking problem was not near as bad even though traffic was heavier. This problem has to be investigated more thoroughly and a solution needs to be found before there is a mid-air collision due to the fact that the O'hare radar cannot track aircraft during one of the most crucial segments of flight.

Original NASA ASRS Text

Title: RADAR TRACKING PROBLEM AT ORD CAUSES TARGETS TO GO INTO COAST STATUS ON DOWNWIND.

Narrative: THE BEACON TRACKING SYS AT O'HARE HAS BECOME UNSATISFACTORY DURING CERTAIN TIMES OF THE DAY. WHILE RUNNING PARALLEL VISUAL APCHS TO 27L AND 27R, 100 PERCENT OF THE IFR TARGETS WENT INTO COAST STATUS ON DOWNWIND, BASE AND INTERMITTENTLY ON FINAL. IT WAS THE WORST I HAVE SEEN IN RECENT MONTHS. WITHOUT TRACKING DATA, THE CTLR HAD NO IDEA OF ACFT ALT AND AIRSPD. HAVING TO ASK PLTS THEIR ALT AND SPD 4 OR 5 TIMES WHILE ON THE APCH INCREASED THE CTLR'S WORKLOAD TO A VERY UNSAFE LEVEL. EARLIER DURING THE SHIFT, THE TRACKING PROBLEM WAS NOT NEAR AS BAD EVEN THOUGH TFC WAS HEAVIER. THIS PROBLEM HAS TO BE INVESTIGATED MORE THOROUGHLY AND A SOLUTION NEEDS TO BE FOUND BEFORE THERE IS A MID-AIR COLLISION DUE TO THE FACT THAT THE O'HARE RADAR CANNOT TRACK ACFT DURING ONE OF THE MOST CRUCIAL SEGMENTS OF FLT.

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.