Narrative:

Just prior to takeoff, at about X:30 am, riverside tower shut down due to electrical failure. Thus the airport became uncontrolled. I had recently purchased an intercom and was eager to try it out on this flight. My plane was an small aircraft equipped only with a hand-held microphone. There was no built-in push-to-talk button or intercom. So I hooked my new intercom's y-adapter plug into the microphone jack and plugged my portable push-to-talk switch into the 'pilot' side of the y-adapter. My passenger had no push-to-talk switch, we both wore headsets and could communicate easily over the intercom. Because the tower was closed and airport uncontrolled, I self-announced my departure position over the CTAF. I assumed my xmissions were heard by other traffic. But because two-way communication wasn't necessary, this was not confirmed. My entire flight avoided air traffic area's and arsa's and there were no lndgs until my return to riverside. Therefore I had no reason to believe I had no transmission capability. I grew a bit suspicious, however, when I called hemet unicom for advisories. When no one answered I figured I was either too far away or the station was closed. But I sensed something might be wrong with my radio so I returned to riverside. I monitored the CTAF (121) from about 15 mi out and entered the pattern on a left 45 degree approach level at pattern altitude (1000' AGL). I announced my position to traffic on each leg. On the downwind however, I suddenly found myself too close to several aircraft. One aircraft was inside my position about 100' away. I asked anyone in the pattern to give me a radio check and no one replied. At this point I realized no one could hear me. Tower ATC, which was monitoring the CTAF radioed for me to identify myself. And it seemed that planes were swarming all around my position. At this point to establish communications, I yanked out the intercom wiring and plugged in the hand-held microphone. That worked. Traffic began to hear me. By this time, though, I was on 1 mi final, with one plane about to takeoff and another ahead of me for landing. I did some south turns and a 360 degree turn for spacing. That still wasn't enough. So I decided to go around. My pattern and heading and radio work from this point on were normal. Afterward, my instrument and I checked over the intercom by calling ground control for a radio check. We discovered that the y-adapter is mislabeled on one side (the pilot and copilot labels are reversed). I had plugged my p-t-T cable into the copilot jack even though it was labeled 'pilot' on one side.

Related reports:

Google
 

Original NASA ASRS Text

Title: SMA PLT WITH NEW INTERCOM EQUIPMENT ENTERED ATA WITH NO CONTACT. FINALLY REALIZED PROBLEM AND REVERTED TO HAND HELD MIKE AFTER GO AROUND.

Narrative: JUST PRIOR TO TKOF, AT ABOUT X:30 AM, RIVERSIDE TWR SHUT DOWN DUE TO ELECTRICAL FAILURE. THUS THE ARPT BECAME UNCTLED. I HAD RECENTLY PURCHASED AN INTERCOM AND WAS EAGER TO TRY IT OUT ON THIS FLT. MY PLANE WAS AN SMA EQUIPPED ONLY WITH A HAND-HELD MIKE. THERE WAS NO BUILT-IN PUSH-TO-TALK BUTTON OR INTERCOM. SO I HOOKED MY NEW INTERCOM'S Y-ADAPTER PLUG INTO THE MICROPHONE JACK AND PLUGGED MY PORTABLE PUSH-TO-TALK SWITCH INTO THE 'PLT' SIDE OF THE Y-ADAPTER. MY PAX HAD NO PUSH-TO-TALK SWITCH, WE BOTH WORE HEADSETS AND COULD COMMUNICATE EASILY OVER THE INTERCOM. BECAUSE THE TWR WAS CLOSED AND ARPT UNCTLED, I SELF-ANNOUNCED MY DEP POS OVER THE CTAF. I ASSUMED MY XMISSIONS WERE HEARD BY OTHER TFC. BUT BECAUSE TWO-WAY COM WASN'T NECESSARY, THIS WAS NOT CONFIRMED. MY ENTIRE FLT AVOIDED ATA'S AND ARSA'S AND THERE WERE NO LNDGS UNTIL MY RETURN TO RIVERSIDE. THEREFORE I HAD NO REASON TO BELIEVE I HAD NO XMISSION CAPABILITY. I GREW A BIT SUSPICIOUS, HOWEVER, WHEN I CALLED HEMET UNICOM FOR ADVISORIES. WHEN NO ONE ANSWERED I FIGURED I WAS EITHER TOO FAR AWAY OR THE STATION WAS CLOSED. BUT I SENSED SOMETHING MIGHT BE WRONG WITH MY RADIO SO I RETURNED TO RIVERSIDE. I MONITORED THE CTAF (121) FROM ABOUT 15 MI OUT AND ENTERED THE PATTERN ON A LEFT 45 DEG APCH LEVEL AT PATTERN ALT (1000' AGL). I ANNOUNCED MY POSITION TO TFC ON EACH LEG. ON THE DOWNWIND HOWEVER, I SUDDENLY FOUND MYSELF TOO CLOSE TO SEVERAL ACFT. ONE ACFT WAS INSIDE MY POS ABOUT 100' AWAY. I ASKED ANYONE IN THE PATTERN TO GIVE ME A RADIO CHK AND NO ONE REPLIED. AT THIS POINT I REALIZED NO ONE COULD HEAR ME. TWR ATC, WHICH WAS MONITORING THE CTAF RADIOED FOR ME TO IDENTIFY MYSELF. AND IT SEEMED THAT PLANES WERE SWARMING ALL AROUND MY POS. AT THIS POINT TO ESTABLISH COMS, I YANKED OUT THE INTERCOM WIRING AND PLUGGED IN THE HAND-HELD MICROPHONE. THAT WORKED. TFC BEGAN TO HEAR ME. BY THIS TIME, THOUGH, I WAS ON 1 MI FINAL, WITH ONE PLANE ABOUT TO TKOF AND ANOTHER AHEAD OF ME FOR LNDG. I DID SOME S TURNS AND A 360 DEG TURN FOR SPACING. THAT STILL WASN'T ENOUGH. SO I DECIDED TO GO AROUND. MY PATTERN AND HDG AND RADIO WORK FROM THIS POINT ON WERE NORMAL. AFTERWARD, MY INSTR AND I CHKED OVER THE INTERCOM BY CALLING GND CTL FOR A RADIO CHK. WE DISCOVERED THAT THE Y-ADAPTER IS MISLABELED ON ONE SIDE (THE PLT AND COPLT LABELS ARE REVERSED). I HAD PLUGGED MY P-T-T CABLE INTO THE COPLT JACK EVEN THOUGH IT WAS LABELED 'PLT' ON ONE SIDE.

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.