Narrative:

Departed sql, handed off to sfo on 120.5, assigned squawk and proceeded northbound, west of highway 101 at 1500' as assigned by sfo tower. After passing sfo and approaching what is locally known as sign hill I lost radio communications with sfo due to loud squelch noise, interference, stuck microphone on frequency, etc, exact cause unknown. I continued northbound west of highway 101 until clear of the 8000' to ground segment of the TCA. Tried other radio frequency selections in area. They appeared normal, but unable to contact or hear sfo. At this time I was clear of sfo and continued on own navigation and switched code to 1200. Unknown to me as to what caused this problem and I encountered no other traffic. This concerned me since I was not able to contact tower, they were unable to contact me, and so I was not handed off, and as I was clear of the innermost circle of TCA early during this problem I was in a legal VFR area and not required to be in or under tower's control. Callback conversation with reporter revealed the following: reporter unable to explain what caused communication loss. He owns the aircraft involved and says the radio package works normally in all respects and did at the time with other frequencys but could not talk with sfo. Reporter is associated with sheriff patrol and flies surveillance missions in that area. Has experience communication problems there before but never as severe as this one. There has been no FAA follow-up on this incident. Reporter realized he had communication loss with sfo on both radios and both transmit and receive only a few moments before exiting sfo TCA and TA airspace and did not think of squawking 7600, but did change to 1200 a few moments later.

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Original NASA ASRS Text

Title: SMA, CLEARED INTO SFO TCA, EXPERIENCES LOSS OF COM FREQ.

Narrative: DEPARTED SQL, HANDED OFF TO SFO ON 120.5, ASSIGNED SQUAWK AND PROCEEDED NBND, W OF HWY 101 AT 1500' AS ASSIGNED BY SFO TWR. AFTER PASSING SFO AND APCHING WHAT IS LOCALLY KNOWN AS SIGN HILL I LOST RADIO COMS WITH SFO DUE TO LOUD SQUELCH NOISE, INTERFERENCE, STUCK MIC ON FREQ, ETC, EXACT CAUSE UNKNOWN. I CONTINUED NBOUND W OF HWY 101 UNTIL CLR OF THE 8000' TO GND SEGMENT OF THE TCA. TRIED OTHER RADIO FREQ SELECTIONS IN AREA. THEY APPEARED NORMAL, BUT UNABLE TO CONTACT OR HEAR SFO. AT THIS TIME I WAS CLR OF SFO AND CONTINUED ON OWN NAV AND SWITCHED CODE TO 1200. UNKNOWN TO ME AS TO WHAT CAUSED THIS PROB AND I ENCOUNTERED NO OTHER TFC. THIS CONCERNED ME SINCE I WAS NOT ABLE TO CONTACT TWR, THEY WERE UNABLE TO CONTACT ME, AND SO I WAS NOT HANDED OFF, AND AS I WAS CLR OF THE INNERMOST CIRCLE OF TCA EARLY DURING THIS PROB I WAS IN A LEGAL VFR AREA AND NOT REQUIRED TO BE IN OR UNDER TWR'S CTL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR UNABLE TO EXPLAIN WHAT CAUSED COM LOSS. HE OWNS THE ACFT INVOLVED AND SAYS THE RADIO PACKAGE WORKS NORMALLY IN ALL RESPECTS AND DID AT THE TIME WITH OTHER FREQS BUT COULD NOT TALK WITH SFO. RPTR IS ASSOCIATED WITH sheriff PATROL AND FLIES SURVEILLANCE MISSIONS IN THAT AREA. HAS EXPERIENCE COM PROBS THERE BEFORE BUT NEVER AS SEVERE AS THIS ONE. THERE HAS BEEN NO FAA FOLLOW-UP ON THIS INCIDENT. RPTR REALIZED HE HAD COM LOSS WITH SFO ON BOTH RADIOS AND BOTH XMIT AND RECEIVE ONLY A FEW MOMENTS BEFORE EXITING SFO TCA AND TA AIRSPACE AND DID NOT THINK OF SQUAWKING 7600, BUT DID CHANGE TO 1200 A FEW MOMENTS LATER.

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.