Narrative:

After landing at mdw and deplaning my son at the FBO, I prepared to return home (although there had been some interference via headphones on approach, it had not seemed to prohibit communication). Upon checking ATIS before startup at mdw, communication (information x-ray) was clearly received. After startup, communication attempts with ground received considerable interference as I was instructed to taxi to 31C. When I requested clearance to cross runways 4R/22L, I was told by ground that I had already been given that instruction, and I proceeded to the 31C runup area. The radio had intermittently less interference with manipulations. After the pre-takeoff runup, I called the tower informing them that I was ready for departure. I was informed, however, that I was still on ground frequency, and I changed to tower frequency, informing tower, after several attempts, that I was ready for departure, and, although experiencing interference, understood I was cleared for takeoff on 31C and replied to tower that I was cleared for takeoff on 31C -- roger. I then entered 31C on a takeoff roll seeing no other traffic. Shortly after rotation, I heard the tower ask if I had heard them tell me to hold short. I replied that I had not heard that. I was asked my departure heading and I replied 240-245 degrees. Tower then instructed me to continue VFR and later released me from radar service and to squawk 1200. Upon returning to my home base, I asked for unicom advisory but received no answer and did give pattern position and intent. After landing, I was told that, although I was recognized, my transmission was garbled and an advisory had been given to me. It was suggested I attempt to transmit after shutdown. This procedure revealed that we were able to communicate with little static. It also revealed that the volume knob was so loose that only a couple of millimeters would shut off the volume. The engine had been running rough on the trip, (magnetos, carburetor ht, and fuel contamination had all checked properly). The FBO recommended checking the spark plugs and leads. Spark plugs have been purchased for installation and leads will be checked as will the repair of the volume knob. Better radio maintenance should have prevented radio problems. More rest and less anxiety could have alerted the pilot to problems earlier.

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Original NASA ASRS Text

Title: UNAUTH RWY ENTRY OP TKOF.

Narrative: AFTER LNDG AT MDW AND DEPLANING MY SON AT THE FBO, I PREPARED TO RETURN HOME (ALTHOUGH THERE HAD BEEN SOME INTERFERENCE VIA HEADPHONES ON APCH, IT HAD NOT SEEMED TO PROHIBIT COM). UPON CHKING ATIS BEFORE STARTUP AT MDW, COM (INFO X-RAY) WAS CLRLY RECEIVED. AFTER STARTUP, COM ATTEMPTS WITH GND RECEIVED CONSIDERABLE INTERFERENCE AS I WAS INSTRUCTED TO TAXI TO 31C. WHEN I REQUESTED CLRNC TO CROSS RWYS 4R/22L, I WAS TOLD BY GND THAT I HAD ALREADY BEEN GIVEN THAT INSTRUCTION, AND I PROCEEDED TO THE 31C RUNUP AREA. THE RADIO HAD INTERMITTENTLY LESS INTERFERENCE WITH MANIPULATIONS. AFTER THE PRE-TKOF RUNUP, I CALLED THE TWR INFORMING THEM THAT I WAS READY FOR DEP. I WAS INFORMED, HOWEVER, THAT I WAS STILL ON GND FREQ, AND I CHANGED TO TWR FREQ, INFORMING TWR, AFTER SEVERAL ATTEMPTS, THAT I WAS READY FOR DEP, AND, ALTHOUGH EXPERIENCING INTERFERENCE, UNDERSTOOD I WAS CLRED FOR TKOF ON 31C AND REPLIED TO TWR THAT I WAS CLRED FOR TKOF ON 31C -- ROGER. I THEN ENTERED 31C ON A TKOF ROLL SEEING NO OTHER TFC. SHORTLY AFTER ROTATION, I HEARD THE TWR ASK IF I HAD HEARD THEM TELL ME TO HOLD SHORT. I REPLIED THAT I HAD NOT HEARD THAT. I WAS ASKED MY DEP HDG AND I REPLIED 240-245 DEGS. TWR THEN INSTRUCTED ME TO CONTINUE VFR AND LATER RELEASED ME FROM RADAR SVC AND TO SQUAWK 1200. UPON RETURNING TO MY HOME BASE, I ASKED FOR UNICOM ADVISORY BUT RECEIVED NO ANSWER AND DID GIVE PATTERN POS AND INTENT. AFTER LNDG, I WAS TOLD THAT, ALTHOUGH I WAS RECOGNIZED, MY XMISSION WAS GARBLED AND AN ADVISORY HAD BEEN GIVEN TO ME. IT WAS SUGGESTED I ATTEMPT TO XMIT AFTER SHUTDOWN. THIS PROC REVEALED THAT WE WERE ABLE TO COMMUNICATE WITH LITTLE STATIC. IT ALSO REVEALED THAT THE VOLUME KNOB WAS SO LOOSE THAT ONLY A COUPLE OF MILLIMETERS WOULD SHUT OFF THE VOLUME. THE ENG HAD BEEN RUNNING ROUGH ON THE TRIP, (MAGNETOS, CARB HT, AND FUEL CONTAMINATION HAD ALL CHKED PROPERLY). THE FBO RECOMMENDED CHKING THE SPARK PLUGS AND LEADS. SPARK PLUGS HAVE BEEN PURCHASED FOR INSTALLATION AND LEADS WILL BE CHKED AS WILL THE REPAIR OF THE VOLUME KNOB. BETTER RADIO MAINT SHOULD HAVE PREVENTED RADIO PROBS. MORE REST AND LESS ANXIETY COULD HAVE ALERTED THE PLT TO PROBS EARLIER.

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.