Aircraft being displayed on radar in wrong position.

Attributes
ACN	255862
Time
Date	199310
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : slc
State Reference	UT
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : slc tower : cvg
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : radar
ASRS Report	255862
Person 2
Affiliation	government : faa
Function	oversight : supervisor
Qualification	controller : radar
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other

Narrative:

I was working local control in slc tower. At the time of radar malfunction a heavy departure bank was in progress with heavy VFR arrs and departures. The ASR-9 radar began displaying aircraft in the wrong position. Aircraft that were 2 mi northeast of the airport were being displayed on the departure centerline, 2 mi from the end of the runway. Previously depicted aircraft dropped from the screen. Departure aircraft were not acquiring until they were 5 mi north. The radar was displaying cars, trucks, and trains. Severe ring around was experienced. Severe WX was displayed although visibility was cavu. This situation lasted approximately 15 mins. I considered the radar unusable although I was instructed by the supervisor on duty to continue using it. I invoked protection under article 65 of natca/FAA agreement. If this radar malfunction had occurred during IFR conditions, an incident could have very well taken place. I have no recommendations except fix the ASR-9. This is a common occurrence.

Original NASA ASRS Text

Title: ACFT BEING DISPLAYED ON RADAR IN WRONG POS.

Narrative: I WAS WORKING LCL CTL IN SLC TWR. AT THE TIME OF RADAR MALFUNCTION A HVY DEP BANK WAS IN PROGRESS WITH HVY VFR ARRS AND DEPS. THE ASR-9 RADAR BEGAN DISPLAYING ACFT IN THE WRONG POS. ACFT THAT WERE 2 MI NE OF THE ARPT WERE BEING DISPLAYED ON THE DEP CTRLINE, 2 MI FROM THE END OF THE RWY. PREVIOUSLY DEPICTED ACFT DROPPED FROM THE SCREEN. DEP ACFT WERE NOT ACQUIRING UNTIL THEY WERE 5 MI N. THE RADAR WAS DISPLAYING CARS, TRUCKS, AND TRAINS. SEVERE RING AROUND WAS EXPERIENCED. SEVERE WX WAS DISPLAYED ALTHOUGH VISIBILITY WAS CAVU. THIS SIT LASTED APPROX 15 MINS. I CONSIDERED THE RADAR UNUSABLE ALTHOUGH I WAS INSTRUCTED BY THE SUPVR ON DUTY TO CONTINUE USING IT. I INVOKED PROTECTION UNDER ARTICLE 65 OF NATCA/FAA AGREEMENT. IF THIS RADAR MALFUNCTION HAD OCCURRED DURING IFR CONDITIONS, AN INCIDENT COULD HAVE VERY WELL TAKEN PLACE. I HAVE NO RECOMMENDATIONS EXCEPT FIX THE ASR-9. THIS IS A COMMON OCCURRENCE.

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.