ATC radar equipment problem. Aircraft equipment problem transponder antenna location.

Attributes
ACN	207048
Time
Date	199204
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : oak
State Reference	CA
Altitude	msl bound lower : 7500 msl bound upper : 7500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Experience	controller military : 4 controller radar : 3
ASRS Report	207048
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Small aircraft X was climbing from 4500 ft to 7500 ft through the TCA. We (bay TRACON) were not receiving the aircraft's mode C, this was the only aircraft whose mode C was not being processed by the ARTS at the time, but several times during the day different aircraft's mode C's will disappear. ZOA sectors 40, 41 and 24 were receiving a valid mode C without interruptions as well as sck tracy sector. We are having several problems with our ARTS from airspds being incorrect on final for runway 27 at oak to losing an entire quadrant of transponder information for up to 4 seconds (sometimes more). I feel that this is an unsafe system for the amount of traffic in the bay area, the supervisors can't seem to do anything about it. This will probably contribute to less than standard separation in the near future and should be investigated as soon as possible.

Original NASA ASRS Text

Title: ATC RADAR EQUIP PROBLEM. ACFT EQUIP PROBLEM TRANSPONDER ANTENNA LOCATION.

Narrative: SMA X WAS CLBING FROM 4500 FT TO 7500 FT THROUGH THE TCA. WE (BAY TRACON) WERE NOT RECEIVING THE ACFT'S MODE C, THIS WAS THE ONLY ACFT WHOSE MODE C WAS NOT BEING PROCESSED BY THE ARTS AT THE TIME, BUT SEVERAL TIMES DURING THE DAY DIFFERENT ACFT'S MODE C'S WILL DISAPPEAR. ZOA SECTORS 40, 41 AND 24 WERE RECEIVING A VALID MODE C WITHOUT INTERRUPTIONS AS WELL AS SCK TRACY SECTOR. WE ARE HAVING SEVERAL PROBLEMS WITH OUR ARTS FROM AIRSPDS BEING INCORRECT ON FINAL FOR RWY 27 AT OAK TO LOSING AN ENTIRE QUADRANT OF TRANSPONDER INFO FOR UP TO 4 SECONDS (SOMETIMES MORE). I FEEL THAT THIS IS AN UNSAFE SYS FOR THE AMOUNT OF TFC IN THE BAY AREA, THE SUPERVISORS CAN'T SEEM TO DO ANYTHING ABOUT IT. THIS WILL PROBABLY CONTRIBUTE TO LTSS IN THE NEAR FUTURE AND SHOULD BE INVESTIGATED AS SOON AS POSSIBLE.

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.