Narrative:

I was en route from nut tree airport to sjc, VFR clear, visibility unlimited. Approximately 15-17 NM from sjc, I contacted bay approach for permission to enter the sjc arsa at the 5 NM ring. At that point I was inside the 30 NM sfo encoder ring, and 4000' below the sfo TCA outer ring floor. Bay approach gave me a transponder code and asked for an identify. I complied. Several mins later bay approach advised not receiving transponder and to recycle and identify again. Also to stay clear of sfo TCA and sjc arsa. At that time I slowed the aircraft level at 2000' MSL, reset transponder and identify. The transponder interrogation light was blinking and on. Pushing identify went to a solid light for the required time interval, then returned to blinking--all indications of normal function. Bay approach advised still not receiving transponder and handed me over to sjc tower. They radar idented me by vectoring a 90 degree turn away from the arsa, then cleared me to enter arsa and report downwind. Upon landing I was asked to call the tower supervisor, which I did. I explained the situation that the transponder appeared to be working from all the normal indications, plus the test function. I tried to find someone who could test it for me on the ground in sjc, but it was sunday noon time and no one could be found. Approximately at pm:00 hours, I called the tower to get a waiver to leave the arsa, which was obtained. I called bay TRACON to get a waiver to pass out of the 30 NM encoder ring from sfo. This was also obtained. I took off from sjc and proceeded directly to nut tree airport (home base). Investigating the problem on monday, it was found the transponder had come slightly loose from tray and the antenna and power supply was intermittent. Transponder was tightened back into tray and function checked ok. Since I had been well clear of TCA (sfo) and sjc arsa, I had no reason to call bay approach until 10-15 NM out. It was at this time I first knew there was a problem with my transponder/encoder, but I was well within the 30 NM encoding ring. I feel there is no practical solution to this problem, since there is no required call to enter the 30 mi ring, nor should there be. I might add that at no time did I even come close to the sfo TCA or the sjc arsa.

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Original NASA ASRS Text

Title: SMA IN PROX OF ARSA AND WITHIN 30 MILE RING OF SFO TCA WITHOUT OPERATIVE TRANSPONDER.

Narrative: I WAS ENRTE FROM NUT TREE ARPT TO SJC, VFR CLR, VISIBILITY UNLIMITED. APPROX 15-17 NM FROM SJC, I CONTACTED BAY APCH FOR PERMISSION TO ENTER THE SJC ARSA AT THE 5 NM RING. AT THAT POINT I WAS INSIDE THE 30 NM SFO ENCODER RING, AND 4000' BELOW THE SFO TCA OUTER RING FLOOR. BAY APCH GAVE ME A XPONDER CODE AND ASKED FOR AN IDENT. I COMPLIED. SEVERAL MINS LATER BAY APCH ADVISED NOT RECEIVING XPONDER AND TO RECYCLE AND IDENT AGAIN. ALSO TO STAY CLR OF SFO TCA AND SJC ARSA. AT THAT TIME I SLOWED THE ACFT LEVEL AT 2000' MSL, RESET XPONDER AND IDENT. THE XPONDER INTERROGATION LIGHT WAS BLINKING AND ON. PUSHING IDENT WENT TO A SOLID LIGHT FOR THE REQUIRED TIME INTERVAL, THEN RETURNED TO BLINKING--ALL INDICATIONS OF NORMAL FUNCTION. BAY APCH ADVISED STILL NOT RECEIVING XPONDER AND HANDED ME OVER TO SJC TWR. THEY RADAR IDENTED ME BY VECTORING A 90 DEG TURN AWAY FROM THE ARSA, THEN CLRED ME TO ENTER ARSA AND RPT DOWNWIND. UPON LNDG I WAS ASKED TO CALL THE TWR SUPVR, WHICH I DID. I EXPLAINED THE SITUATION THAT THE XPONDER APPEARED TO BE WORKING FROM ALL THE NORMAL INDICATIONS, PLUS THE TEST FUNCTION. I TRIED TO FIND SOMEONE WHO COULD TEST IT FOR ME ON THE GND IN SJC, BUT IT WAS SUNDAY NOON TIME AND NO ONE COULD BE FOUND. APPROX AT PM:00 HRS, I CALLED THE TWR TO GET A WAIVER TO LEAVE THE ARSA, WHICH WAS OBTAINED. I CALLED BAY TRACON TO GET A WAIVER TO PASS OUT OF THE 30 NM ENCODER RING FROM SFO. THIS WAS ALSO OBTAINED. I TOOK OFF FROM SJC AND PROCEEDED DIRECTLY TO NUT TREE ARPT (HOME BASE). INVESTIGATING THE PROB ON MONDAY, IT WAS FOUND THE XPONDER HAD COME SLIGHTLY LOOSE FROM TRAY AND THE ANTENNA AND PWR SUPPLY WAS INTERMITTENT. XPONDER WAS TIGHTENED BACK INTO TRAY AND FUNCTION CHKED OK. SINCE I HAD BEEN WELL CLR OF TCA (SFO) AND SJC ARSA, I HAD NO REASON TO CALL BAY APCH UNTIL 10-15 NM OUT. IT WAS AT THIS TIME I FIRST KNEW THERE WAS A PROB WITH MY XPONDER/ENCODER, BUT I WAS WELL WITHIN THE 30 NM ENCODING RING. I FEEL THERE IS NO PRACTICAL SOLUTION TO THIS PROB, SINCE THERE IS NO REQUIRED CALL TO ENTER THE 30 MI RING, NOR SHOULD THERE BE. I MIGHT ADD THAT AT NO TIME DID I EVEN COME CLOSE TO THE SFO TCA OR THE SJC ARSA.

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.