Narrative:

This problem arises almost daily at this facility. The problem arises from the fact that most of the operating hours at this facility, the local control and ground control, are handled by 1 controller, simultaneously broadcasting on both frequencys. This makes the cockpit environment confusing at times because of the quantity of activity (vehicular traffic across the airport is unusually heavy) and the fact the clrncs and instructions can occur intended for 1 aircraft and received as for another. I believe such was the case today. We called the tower at the hold short line, 'ready for takeoff.' 'taxi into position and hold,' with a TA of a landing aircraft was received. My student acknowledged only with 'roger,' and began to taxi onto the runway. I was about to acknowledge the hold short instruction, but at that time received what I perceived as a takeoff clearance. I acknowledged and we continued the taxi into the takeoff. We never stopped on the runway. The aircraft that landed before had cleared the runway and there was no traffic on the runway. At an altitude of 300 ft, I observed a yellow home built airplane crossing the runway some 3400 ft from the departure end. At 500 ft the tower controller informed me he had not given me takeoff clearance, and that I caused a conflict with the taxiing aircraft. The problem may have been compounded by 2 other factors: 1) the controller has a great deal of trouble articulating and often runs his words together. I may have responded to an instruction given to the aircraft on the ground. 2) I found that we had an intermittent microphone switch and my transmission may not have been received by the controller. If this facility does not have sufficient traffic for a tower now, and cannot get enough help to staff adequately, closing the facility might be a solution.

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Original NASA ASRS Text

Title: UNAUTH TKOF IN A BE77 CREATES A POTENTIAL CONFLICT WITH SMA TFC TAXIING ACROSS THE ACTIVE RWY.

Narrative: THIS PROB ARISES ALMOST DAILY AT THIS FACILITY. THE PROB ARISES FROM THE FACT THAT MOST OF THE OPERATING HRS AT THIS FACILITY, THE LCL CTL AND GND CTL, ARE HANDLED BY 1 CTLR, SIMULTANEOUSLY BROADCASTING ON BOTH FREQS. THIS MAKES THE COCKPIT ENVIRONMENT CONFUSING AT TIMES BECAUSE OF THE QUANTITY OF ACTIVITY (VEHICULAR TFC ACROSS THE ARPT IS UNUSUALLY HVY) AND THE FACT THE CLRNCS AND INSTRUCTIONS CAN OCCUR INTENDED FOR 1 ACFT AND RECEIVED AS FOR ANOTHER. I BELIEVE SUCH WAS THE CASE TODAY. WE CALLED THE TWR AT THE HOLD SHORT LINE, 'READY FOR TKOF.' 'TAXI INTO POS AND HOLD,' WITH A TA OF A LNDG ACFT WAS RECEIVED. MY STUDENT ACKNOWLEDGED ONLY WITH 'ROGER,' AND BEGAN TO TAXI ONTO THE RWY. I WAS ABOUT TO ACKNOWLEDGE THE HOLD SHORT INSTRUCTION, BUT AT THAT TIME RECEIVED WHAT I PERCEIVED AS A TKOF CLRNC. I ACKNOWLEDGED AND WE CONTINUED THE TAXI INTO THE TKOF. WE NEVER STOPPED ON THE RWY. THE ACFT THAT LANDED BEFORE HAD CLRED THE RWY AND THERE WAS NO TFC ON THE RWY. AT AN ALT OF 300 FT, I OBSERVED A YELLOW HOME BUILT AIRPLANE XING THE RWY SOME 3400 FT FROM THE DEP END. AT 500 FT THE TWR CTLR INFORMED ME HE HAD NOT GIVEN ME TKOF CLRNC, AND THAT I CAUSED A CONFLICT WITH THE TAXIING ACFT. THE PROB MAY HAVE BEEN COMPOUNDED BY 2 OTHER FACTORS: 1) THE CTLR HAS A GREAT DEAL OF TROUBLE ARTICULATING AND OFTEN RUNS HIS WORDS TOGETHER. I MAY HAVE RESPONDED TO AN INSTRUCTION GIVEN TO THE ACFT ON THE GND. 2) I FOUND THAT WE HAD AN INTERMITTENT MIKE SWITCH AND MY XMISSION MAY NOT HAVE BEEN RECEIVED BY THE CTLR. IF THIS FACILITY DOES NOT HAVE SUFFICIENT TFC FOR A TWR NOW, AND CANNOT GET ENOUGH HELP TO STAFF ADEQUATELY, CLOSING THE FACILITY MIGHT BE A SOLUTION.

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.