Narrative:

Immediately after takeoff from runway 33 at dca, I noticed a silence over the tower frequency on my #1 communication radio. The transmit indicator on the radio was on, indicating that I had a hot microphone. I noticed that movement of the control yoke left or right would make the transmit light go out, but only intermittently. I switched the radio transmit selector radio #2, which caused the transmit light on radio #2 to light up. Rekeying all push-to-talk switches did not solve the problem. I unplugged all headphone jacks and attempted using the hand held microphone and speaker west/O result. I figured the problem was in a push-to-talk wiring or switch malfunction, neither of which is accessible to disconnect in flight. I realized that as long as I had a hot microphone on the tower or departure frequencys, I was blocking other aircraft and ATC xmissions. Since I was unable to receive any communications, I turned off both communication radios. I followed the last clearance received which was obtained prior to taxi: depart northwest over the river for vectors out of the TCA, maintain 2000'. I leveled at 2000' MSL and continued up the river. Once outside the TCA latitude limits, I descended to 1400' MSL. At this altitude I was able to fly south to my destination west/O flying in the TCA. Additionally, this allowed me to remain east of the dulles arsa. I was not certain if dulles 'knew' my radar target and accordingly, remained clear of the arsa. Using visibility references, VFR charts and DME readings from dca and aml VORTAC's, I remained out of both the iad arsa and the dca TCA. I attempted to call the dca tower by telephone upon landing to explain this occurrence but no one answered.

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Original NASA ASRS Text

Title: IMMEDIATELY AFTER TKOF FLT EXPERIENCED AN UNKNOWN FAILURE IN THE RADIO MICROPHONE EQUIPMENT. REPORTER TURNED OFF BOTH COM RADIOS TO AVOID CAUSING FURTHER FREQ PROBLEMS FOR ATC AND FLEW HIS LAST ASSIGNED CLRNC.

Narrative: IMMEDIATELY AFTER TKOF FROM RWY 33 AT DCA, I NOTICED A SILENCE OVER THE TWR FREQ ON MY #1 COM RADIO. THE XMIT INDICATOR ON THE RADIO WAS ON, INDICATING THAT I HAD A HOT MIC. I NOTICED THAT MOVEMENT OF THE CONTROL YOKE LEFT OR RIGHT WOULD MAKE THE XMIT LIGHT GO OUT, BUT ONLY INTERMITTENTLY. I SWITCHED THE RADIO XMIT SELECTOR RADIO #2, WHICH CAUSED THE XMIT LIGHT ON RADIO #2 TO LIGHT UP. REKEYING ALL PUSH-TO-TALK SWITCHES DID NOT SOLVE THE PROB. I UNPLUGGED ALL HEADPHONE JACKS AND ATTEMPTED USING THE HAND HELD MIC AND SPEAKER W/O RESULT. I FIGURED THE PROB WAS IN A PUSH-TO-TALK WIRING OR SWITCH MALFUNCTION, NEITHER OF WHICH IS ACCESSIBLE TO DISCONNECT IN FLT. I REALIZED THAT AS LONG AS I HAD A HOT MIC ON THE TWR OR DEP FREQS, I WAS BLOCKING OTHER ACFT AND ATC XMISSIONS. SINCE I WAS UNABLE TO RECEIVE ANY COMS, I TURNED OFF BOTH COM RADIOS. I FOLLOWED THE LAST CLRNC RECEIVED WHICH WAS OBTAINED PRIOR TO TAXI: DEPART NW OVER THE RIVER FOR VECTORS OUT OF THE TCA, MAINTAIN 2000'. I LEVELED AT 2000' MSL AND CONTINUED UP THE RIVER. ONCE OUTSIDE THE TCA LAT LIMITS, I DSNDED TO 1400' MSL. AT THIS ALT I WAS ABLE TO FLY S TO MY DEST W/O FLYING IN THE TCA. ADDITIONALLY, THIS ALLOWED ME TO REMAIN E OF THE DULLES ARSA. I WAS NOT CERTAIN IF DULLES 'KNEW' MY RADAR TARGET AND ACCORDINGLY, REMAINED CLR OF THE ARSA. USING VIS REFERENCES, VFR CHARTS AND DME READINGS FROM DCA AND AML VORTAC'S, I REMAINED OUT OF BOTH THE IAD ARSA AND THE DCA TCA. I ATTEMPTED TO CALL THE DCA TWR BY TELEPHONE UPON LNDG TO EXPLAIN THIS OCCURRENCE BUT NO ONE ANSWERED.

Data retrieved from NASA's ASRS site as of August 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.