Narrative:

Typically, I set tower/approach airborne frequencys on the #1 communication and ground/clearance delivery frequencys on the #2. At the time, I was taxiing out to depart runway 26. There was an ultra-light aircraft that was departing runway 21 and staying in the pattern. With this in mind, I had received IFR and taxi clearance on the ground control frequency set on the #2 communication radio. During readback over the #2 communication radio there was a loud (feedback?) squeal so I pushed 'off' the #1 communication receive button which eliminated the squeal. Tower then gave me takeoff clearance over the ground frequency as I approached the runway. I considered the ultra-light aircraft for runway 21 but thought he was on downwind. Since I was taxiing south for runway 26 departure I was unable to visually confirm his position. During the takeoff I noticed the ultra-light on go around from the converging runway and wondered why tower gave me clearance to take off. I then noticed the audio selector was still set to the #2 (ground) and the audio button for #1 was out. Quickly switching, I informed the tower over the proper tower frequency. Tower said they had tried to contact me to cancel my takeoff clearance and had to give the other airplane a go around. Thanks to the tower, there was adequate aircraft separation. A primary factor is my effort to hurry my departure and failure to reset/rechk the audio panel. Although accommodating, ATC probably should not have issued me takeoff clearance, considering the other aircraft in the pattern, but since I was in a hurry I was all too happy to accept. Also, the tower probably should have issued the amended hold short instructions over both frequencys. The audio panel is now part of my personal 'last chance' takeoff checklist.

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Original NASA ASRS Text

Title: C208 TAKES OFF AFTER MISSING THE TWR'S AMENDED HOLD SHORT CLRNC DUE TO IMPROPER AUDIO PANEL SETUP. CONFLICTING TFC IS GIVEN A GAR BY TWR.

Narrative: TYPICALLY, I SET TWR/APCH AIRBORNE FREQS ON THE #1 COM AND GND/CLRNC DELIVERY FREQS ON THE #2. AT THE TIME, I WAS TAXIING OUT TO DEPART RWY 26. THERE WAS AN ULTRA-LIGHT ACFT THAT WAS DEPARTING RWY 21 AND STAYING IN THE PATTERN. WITH THIS IN MIND, I HAD RECEIVED IFR AND TAXI CLRNC ON THE GND CTL FREQ SET ON THE #2 COM RADIO. DURING READBACK OVER THE #2 COM RADIO THERE WAS A LOUD (FEEDBACK?) SQUEAL SO I PUSHED 'OFF' THE #1 COM RECEIVE BUTTON WHICH ELIMINATED THE SQUEAL. TWR THEN GAVE ME TKOF CLRNC OVER THE GND FREQ AS I APCHED THE RWY. I CONSIDERED THE ULTRA-LIGHT ACFT FOR RWY 21 BUT THOUGHT HE WAS ON DOWNWIND. SINCE I WAS TAXIING S FOR RWY 26 DEP I WAS UNABLE TO VISUALLY CONFIRM HIS POS. DURING THE TKOF I NOTICED THE ULTRA-LIGHT ON GAR FROM THE CONVERGING RWY AND WONDERED WHY TWR GAVE ME CLRNC TO TAKE OFF. I THEN NOTICED THE AUDIO SELECTOR WAS STILL SET TO THE #2 (GND) AND THE AUDIO BUTTON FOR #1 WAS OUT. QUICKLY SWITCHING, I INFORMED THE TWR OVER THE PROPER TWR FREQ. TWR SAID THEY HAD TRIED TO CONTACT ME TO CANCEL MY TKOF CLRNC AND HAD TO GIVE THE OTHER AIRPLANE A GAR. THANKS TO THE TWR, THERE WAS ADEQUATE ACFT SEPARATION. A PRIMARY FACTOR IS MY EFFORT TO HURRY MY DEP AND FAILURE TO RESET/RECHK THE AUDIO PANEL. ALTHOUGH ACCOMMODATING, ATC PROBABLY SHOULD NOT HAVE ISSUED ME TKOF CLRNC, CONSIDERING THE OTHER ACFT IN THE PATTERN, BUT SINCE I WAS IN A HURRY I WAS ALL TOO HAPPY TO ACCEPT. ALSO, THE TWR PROBABLY SHOULD HAVE ISSUED THE AMENDED HOLD SHORT INSTRUCTIONS OVER BOTH FREQS. THE AUDIO PANEL IS NOW PART OF MY PERSONAL 'LAST CHANCE' TKOF CHKLIST.

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.