Narrative:

Dec, 1989 while en route from lake havasu, az to the riverside municipal airport, I obtained verification that my transponder was functioning properly, and that my mode C altitude encoder was providing correct altitude information. This was the last time I operated the aircraft prior to the incident. Feb, 1990 I departed riverside municipal airport en route to montgomery field, san diego for my aircraft's annual inspection. Riverside ground control and control tower were inoperative due to a power failure, but I had excellent radio communication with other aircraft operating at the airport. I began trying to contact san diego approach on both 124.65 and 132.2. All attempts at contact were negative. Believing my transponder and mode C encoder to be operating properly, I departed julian on a heading of 200 degree magnetic, and held that radial for 18 NM. Then I turned directly for gillespie field. I briefly established contact with san diego center on 132.2, and dialed in the assigned transponder code. I then lost radio contact, and never regained it with center. Prior to arriving at the boundary of area a of the san diego TCA, I had leveled off at 3800' MSL. I established radio contact with montgomery tower. The tower advised me to squawk XXXX and identify, which I did. Tower advised me that they had skin paint but no transponder from my aircraft and that I was cleared for a straight-in approach to runway 28L. This was the first indication I had had that my transponder and mode C encoder were not functioning properly. As I was below the TCA, had already been cleared to land at montgomery, I elected to continue on and land. I realize that I violated the 30 NM mode C rule, but my transponder was blinking in response to radar interrogations, and my mode C had checked good prior to the flight. I was in excess of the 2 yr transponder/mode C certification period, but the WX was VFR and my systems appeared to be working. At no time did I enter any segment of the san diego TCA, communications were good with all stations on the route of flight except san diego approach control. I feel that a major factor in this incident was the communication problem that I experienced at the time when I needed my transponder the most. Although I was using a portable transceiver with a power amplified antenna due to difficulties experienced with the aircraft's internal radios, contact with ontario approach control had been established on previous flts well outside of 40 NM direct range. I also feel that with current technology a portable mode C test device could be developed which would give pilots in the cockpit an indication of altitude information that is being transmitted by their xponders.

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Original NASA ASRS Text

Title: GA SMA FLEW INTO THE 30 NM VEIL BUT UNDER THE SAN TCA WITH INOPERATIVE MODE C ENROUTE TO MYF.

Narrative: DEC, 1989 WHILE ENRTE FROM LAKE HAVASU, AZ TO THE RIVERSIDE MUNI ARPT, I OBTAINED VERIFICATION THAT MY XPONDER WAS FUNCTIONING PROPERLY, AND THAT MY MODE C ALT ENCODER WAS PROVIDING CORRECT ALT INFO. THIS WAS THE LAST TIME I OPERATED THE ACFT PRIOR TO THE INCIDENT. FEB, 1990 I DEPARTED RIVERSIDE MUNI ARPT ENRTE TO MONTGOMERY FIELD, SAN DIEGO FOR MY ACFT'S ANNUAL INSPECTION. RIVERSIDE GND CTL AND CTL TWR WERE INOPERATIVE DUE TO A POWER FAILURE, BUT I HAD EXCELLENT RADIO COM WITH OTHER ACFT OPERATING AT THE ARPT. I BEGAN TRYING TO CONTACT SAN DIEGO APCH ON BOTH 124.65 AND 132.2. ALL ATTEMPTS AT CONTACT WERE NEGATIVE. BELIEVING MY XPONDER AND MODE C ENCODER TO BE OPERATING PROPERLY, I DEPARTED JULIAN ON A HDG OF 200 DEG MAG, AND HELD THAT RADIAL FOR 18 NM. THEN I TURNED DIRECTLY FOR GILLESPIE FIELD. I BRIEFLY ESTABLISHED CONTACT WITH SAN DIEGO CENTER ON 132.2, AND DIALED IN THE ASSIGNED XPONDER CODE. I THEN LOST RADIO CONTACT, AND NEVER REGAINED IT WITH CENTER. PRIOR TO ARRIVING AT THE BOUNDARY OF AREA A OF THE SAN DIEGO TCA, I HAD LEVELED OFF AT 3800' MSL. I ESTABLISHED RADIO CONTACT WITH MONTGOMERY TWR. THE TWR ADVISED ME TO SQUAWK XXXX AND IDENT, WHICH I DID. TWR ADVISED ME THAT THEY HAD SKIN PAINT BUT NO XPONDER FROM MY ACFT AND THAT I WAS CLRED FOR A STRAIGHT-IN APCH TO RWY 28L. THIS WAS THE FIRST INDICATION I HAD HAD THAT MY XPONDER AND MODE C ENCODER WERE NOT FUNCTIONING PROPERLY. AS I WAS BELOW THE TCA, HAD ALREADY BEEN CLRED TO LAND AT MONTGOMERY, I ELECTED TO CONTINUE ON AND LAND. I REALIZE THAT I VIOLATED THE 30 NM MODE C RULE, BUT MY XPONDER WAS BLINKING IN RESPONSE TO RADAR INTERROGATIONS, AND MY MODE C HAD CHECKED GOOD PRIOR TO THE FLT. I WAS IN EXCESS OF THE 2 YR XPONDER/MODE C CERTIFICATION PERIOD, BUT THE WX WAS VFR AND MY SYSTEMS APPEARED TO BE WORKING. AT NO TIME DID I ENTER ANY SEGMENT OF THE SAN DIEGO TCA, COMS WERE GOOD WITH ALL STATIONS ON THE ROUTE OF FLT EXCEPT SAN DIEGO APCH CTL. I FEEL THAT A MAJOR FACTOR IN THIS INCIDENT WAS THE COM PROBLEM THAT I EXPERIENCED AT THE TIME WHEN I NEEDED MY XPONDER THE MOST. ALTHOUGH I WAS USING A PORTABLE TRANSCEIVER WITH A POWER AMPLIFIED ANTENNA DUE TO DIFFICULTIES EXPERIENCED WITH THE ACFT'S INTERNAL RADIOS, CONTACT WITH ONTARIO APCH CTL HAD BEEN ESTABLISHED ON PREVIOUS FLTS WELL OUTSIDE OF 40 NM DIRECT RANGE. I ALSO FEEL THAT WITH CURRENT TECHNOLOGY A PORTABLE MODE C TEST DEVICE COULD BE DEVELOPED WHICH WOULD GIVE PLTS IN THE COCKPIT AN INDICATION OF ALT INFO THAT IS BEING TRANSMITTED BY THEIR XPONDERS.

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.