Reporter at anc TRACON alleges that airways facilities technician caused ASR-9 radar to fail while h...

Attributes
ACN	348769
Time
Date	199610
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : anc
State Reference	AK
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : anc
Operator	common carrier : air carrier
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	descent : approach landing other
Route In Use	approach : visual arrival other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	CV 580
Operating Under FAR Part	Part 121
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 5
ASRS Report	348769
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller non radar : 4 controller radar : 6 flight time total : 20
ASRS Report	348770
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Air Traffic Incident	other
Situations
ATC Facility	other physical facility procedure or policy : unspecified

Narrative:

Anc TRACON radar maintenance advised ATC they were going to perform a maintenance function on the radar. Soon thereafter, things went awry. Aircraft position was instantly off by 10 mi, heading off by 30 degrees. I asked IFR aircraft if he was in VFR conditions, terminated radar service, and advised pilot of radar failure. I instructed pilot to maintain VFR and gave position of known traffic, a potentially conflicting sbound CV58. Pilot advised he had field in sight and was cleared for visual approach. Shortly after, radar returned to normal. No conflict was evident, MD11 shipped to tower. This is the second such occurrence in less than 2 weeks. Supplemental information from acn 348770: radar maintenance advised that they were going to perform maintenance on the rcag. Suddenly all targets were off by several (10-15) mi. The MD80 was nearing terrain in the climb. I could no longer monitor his climb rate with respect to the terrain, and higher MVA he was nearing. Luckily, he was VMC and able to provide his own terrain separation. I had 2 other aircraft (the B737 and a CV58) in the airspace at the time. I felt reasonably certain that they were clear of traffic and terrain, so I took no immediate action. The radar subsequently changed azimuth by about 90 degrees! This same thing happened to me about 2 weeks ago, although this time the technician gave a 'heads up.' but, he said he was only going to work on the rcag, which should not have affected anything. This has got to stop before we kill someone.

Original NASA ASRS Text

Title: RPTR AT ANC TRACON ALLEGES THAT AIRWAYS FACILITIES TECHNICIAN CAUSED ASR-9 RADAR TO FAIL WHILE HE PERFORMED A MAINT FUNCTION. NO INCIDENTS OCCURRED DURING OUTAGE.

Narrative: ANC TRACON RADAR MAINT ADVISED ATC THEY WERE GOING TO PERFORM A MAINT FUNCTION ON THE RADAR. SOON THEREAFTER, THINGS WENT AWRY. ACFT POS WAS INSTANTLY OFF BY 10 MI, HDG OFF BY 30 DEGS. I ASKED IFR ACFT IF HE WAS IN VFR CONDITIONS, TERMINATED RADAR SVC, AND ADVISED PLT OF RADAR FAILURE. I INSTRUCTED PLT TO MAINTAIN VFR AND GAVE POS OF KNOWN TFC, A POTENTIALLY CONFLICTING SBOUND CV58. PLT ADVISED HE HAD FIELD IN SIGHT AND WAS CLRED FOR VISUAL APCH. SHORTLY AFTER, RADAR RETURNED TO NORMAL. NO CONFLICT WAS EVIDENT, MD11 SHIPPED TO TWR. THIS IS THE SECOND SUCH OCCURRENCE IN LESS THAN 2 WKS. SUPPLEMENTAL INFO FROM ACN 348770: RADAR MAINT ADVISED THAT THEY WERE GOING TO PERFORM MAINT ON THE RCAG. SUDDENLY ALL TARGETS WERE OFF BY SEVERAL (10-15) MI. THE MD80 WAS NEARING TERRAIN IN THE CLB. I COULD NO LONGER MONITOR HIS CLB RATE WITH RESPECT TO THE TERRAIN, AND HIGHER MVA HE WAS NEARING. LUCKILY, HE WAS VMC AND ABLE TO PROVIDE HIS OWN TERRAIN SEPARATION. I HAD 2 OTHER ACFT (THE B737 AND A CV58) IN THE AIRSPACE AT THE TIME. I FELT REASONABLY CERTAIN THAT THEY WERE CLR OF TFC AND TERRAIN, SO I TOOK NO IMMEDIATE ACTION. THE RADAR SUBSEQUENTLY CHANGED AZIMUTH BY ABOUT 90 DEGS! THIS SAME THING HAPPENED TO ME ABOUT 2 WKS AGO, ALTHOUGH THIS TIME THE TECHNICIAN GAVE A 'HEADS UP.' BUT, HE SAID HE WAS ONLY GOING TO WORK ON THE RCAG, WHICH SHOULD NOT HAVE AFFECTED ANYTHING. THIS HAS GOT TO STOP BEFORE WE KILL SOMEONE.

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.

Reporter at anc TRACON alleges that airways facilities technician caused ASR-9 radar to fail while he performed a maintenance function. No incidents occurred during outage.