<< >> NASA ASRS Report 313886, August 1995

ATC equipment problem center radar non display of targets. Small transport had conflict with cessna. See and avoid concept.

Attributes
ACN	313886
Time
Date	199508
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eph
State Reference	WA
Altitude	msl bound lower : 9500 msl bound upper : 9500
Environment
Flight Conditions	VMC
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zse
Operator	general aviation : corporate
Make Model Name	Super King Air 200/Huron
Operating Under FAR Part	other : unknown
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	VFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	313886
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 3000 vertical : 0
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

Small transport X asked me (the radar controller on sector 18) if I had any traffic on my radar for him. I displayed nothing in his vicinity. He stated that he descended through a cessna at 9500 ft. During the morning we had noticed that the radar was not displaying all targets -- both primary or transponder targets. Also some targets were tracked and displayed by the backup system (edarc) but not displayed at all by our primary system (NAS). This problem has been noted and reported for several days but has not been fixed. Callback conversation with reporter revealed the following information: reporter stated the BE20 missed the cessna by 1/2 mi as he descended through the cessna's altitude. Reporter stated the radar was taken OTS for 4 days and now displays targets normally.

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Original NASA ASRS Text

Title: ATC EQUIP PROB CTR RADAR NON DISPLAY OF TARGETS. SMT HAD CONFLICT WITH CESSNA. SEE AND AVOID CONCEPT.

Narrative: SMT X ASKED ME (THE RADAR CTLR ON SECTOR 18) IF I HAD ANY TFC ON MY RADAR FOR HIM. I DISPLAYED NOTHING IN HIS VICINITY. HE STATED THAT HE DSNDED THROUGH A CESSNA AT 9500 FT. DURING THE MORNING WE HAD NOTICED THAT THE RADAR WAS NOT DISPLAYING ALL TARGETS -- BOTH PRIMARY OR TRANSPONDER TARGETS. ALSO SOME TARGETS WERE TRACKED AND DISPLAYED BY THE BACKUP SYS (EDARC) BUT NOT DISPLAYED AT ALL BY OUR PRIMARY SYS (NAS). THIS PROB HAS BEEN NOTED AND RPTED FOR SEVERAL DAYS BUT HAS NOT BEEN FIXED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE BE20 MISSED THE CESSNA BY 1/2 MI AS HE DSNDED THROUGH THE CESSNA'S ALT. RPTR STATED THE RADAR WAS TAKEN OTS FOR 4 DAYS AND NOW DISPLAYS TARGETS NORMALLY.

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.