Narrative:

As pilot of a C340 xxxxx, I had received my clearance for an IFR part 135 flight from apa to saa and was taxiing to runway 17L for departure as ground had instructed me. While proceeding to the runway, I informed ground that I would have my run-up completed and would be ready for takeoff upon arriving at the runway hold line. Ground acknowledged my report with, 'roger XXX thank you.' upon reaching the hold line for runway 17L, I stopped short and, being #1 at the line, waited for instructions to monitor the tower frequency as is customary at apa. After approximately 20 seconds, ground asked me if I was ready for takeoff. I replied, 'affirmative, XXX ready for takeoff runway 17L.' I was then instructed to monitor tower frequency for my takeoff clearance. I replied 'XXX going to tower.' I switched to tower frequency and waited. Another 20-30 seconds had passed when I heard a transmission from the tower, 'twin cessna XXX, taxi into position and hold runway 17L.' there was significant radio interference during the transmission, possibly caused by another aircraft. This interference reduced the clarity of the transmission somewhat, however, I clearly heard the voice of a female controller with my call sign and the instruction to taxi onto the runway. I read back, 'twin cessna XXX position and hold runway 17L.' I received no further instructions, clarification or challenge from the tower as I taxied out to runway 17L. I had just begun to line up on the centerline of runway 17L when I heard the same controller who had just given me clearance instructions, 'twin cessna XXX, make an immediate 180 degree turn from runway 17L back to the hold line. You were not cleared onto the runway. Numerous aircraft inbound for landing. King air on 3 mi final.' I turned back toward the hold line and informed the controller that I had received clearance to taxi into position on runway 17L and had read that instruction back to the tower. The controller responded that I had been instructed to 'hold short of runway 17L,' that it was 'no problem' and that I needed to return to the runway hold line. I returned to the hold line for runway 17L and waited for takeoff clearance. Another 8-10 mins passed, during which time 3 aircraft landed on runway 17L, until I was instructed, 'twin cessna XXXX, taxi into position and hold runway 17L.' I acknowledged the clearance with, 'twin cessna XXX, position and hold runway 17L' and began to taxi out to runway 17L. While taxiing into position on runway 17L, I heard the same controller talking to several aircraft inbound including a traffic watch C172 that was on a 3 mi final and cleared to land on runway 17L. Once in position on runway 17L, I waited for takeoff clearance knowing that the traffic watch aircraft was bearing down on me as I sat on the runway. Finally I was instructed, 'twin cessna XXX, fly runway heading. Cleared for takeoff runway 17L.' I acknowledged, 'runway heading, cleared takeoff runway 17L, XXX' and began my takeoff roll. From that point the flight proceeded without further incident. Looking at this incident, I don't know what I would have done differently save asking for verification of the clearance onto runway 17L after that transmission from the tower was interfered with by an unknown source. At apa the tower will scold you if you report your position holding short of a particular runway. Presumably, the practice of not reporting position short of a runway is used to decrease frequency congestion in a very busy airspace, but I believe that it sometimes can cause confusion and error on the part of controller and pilot alike. After being asked if I was ready for takeoff and after waiting 20-30 seconds short of the hold line without moving does an instruction to 'hold short' make sense? I feel that the controller simply made a mistake. I also believe that controller's comment that it was 'no problem' that we had miscommunicated reinforces my position. Everyone makes mistakes occasionally, but in this instance the mistake could have definitely been a problem.

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Original NASA ASRS Text

Title: ATX C340 PLT TAXIED INTO POS AND HELD PER TWR CTLR INSTRUCTIONS. HOWEVER, CTLR SUBSEQUENTLY INSTRUCTED PLT TO DO A 180 DEG TURN AND GO BACK TO THE HOLD LINE.

Narrative: AS PLT OF A C340 XXXXX, I HAD RECEIVED MY CLRNC FOR AN IFR PART 135 FLT FROM APA TO SAA AND WAS TAXIING TO RWY 17L FOR DEP AS GND HAD INSTRUCTED ME. WHILE PROCEEDING TO THE RWY, I INFORMED GND THAT I WOULD HAVE MY RUN-UP COMPLETED AND WOULD BE READY FOR TKOF UPON ARRIVING AT THE RWY HOLD LINE. GND ACKNOWLEDGED MY RPT WITH, 'ROGER XXX THANK YOU.' UPON REACHING THE HOLD LINE FOR RWY 17L, I STOPPED SHORT AND, BEING #1 AT THE LINE, WAITED FOR INSTRUCTIONS TO MONITOR THE TWR FREQ AS IS CUSTOMARY AT APA. AFTER APPROX 20 SECONDS, GND ASKED ME IF I WAS READY FOR TKOF. I REPLIED, 'AFFIRMATIVE, XXX READY FOR TKOF RWY 17L.' I WAS THEN INSTRUCTED TO MONITOR TWR FREQ FOR MY TKOF CLRNC. I REPLIED 'XXX GOING TO TWR.' I SWITCHED TO TWR FREQ AND WAITED. ANOTHER 20-30 SECONDS HAD PASSED WHEN I HEARD A XMISSION FROM THE TWR, 'TWIN CESSNA XXX, TAXI INTO POS AND HOLD RWY 17L.' THERE WAS SIGNIFICANT RADIO INTERFERENCE DURING THE XMISSION, POSSIBLY CAUSED BY ANOTHER ACFT. THIS INTERFERENCE REDUCED THE CLARITY OF THE XMISSION SOMEWHAT, HOWEVER, I CLRLY HEARD THE VOICE OF A FEMALE CTLR WITH MY CALL SIGN AND THE INSTRUCTION TO TAXI ONTO THE RWY. I READ BACK, 'TWIN CESSNA XXX POS AND HOLD RWY 17L.' I RECEIVED NO FURTHER INSTRUCTIONS, CLARIFICATION OR CHALLENGE FROM THE TWR AS I TAXIED OUT TO RWY 17L. I HAD JUST BEGUN TO LINE UP ON THE CTRLINE OF RWY 17L WHEN I HEARD THE SAME CTLR WHO HAD JUST GIVEN ME CLRNC INSTRUCTIONS, 'TWIN CESSNA XXX, MAKE AN IMMEDIATE 180 DEG TURN FROM RWY 17L BACK TO THE HOLD LINE. YOU WERE NOT CLRED ONTO THE RWY. NUMEROUS ACFT INBOUND FOR LNDG. KING AIR ON 3 MI FINAL.' I TURNED BACK TOWARD THE HOLD LINE AND INFORMED THE CTLR THAT I HAD RECEIVED CLRNC TO TAXI INTO POS ON RWY 17L AND HAD READ THAT INSTRUCTION BACK TO THE TWR. THE CTLR RESPONDED THAT I HAD BEEN INSTRUCTED TO 'HOLD SHORT OF RWY 17L,' THAT IT WAS 'NO PROB' AND THAT I NEEDED TO RETURN TO THE RWY HOLD LINE. I RETURNED TO THE HOLD LINE FOR RWY 17L AND WAITED FOR TKOF CLRNC. ANOTHER 8-10 MINS PASSED, DURING WHICH TIME 3 ACFT LANDED ON RWY 17L, UNTIL I WAS INSTRUCTED, 'TWIN CESSNA XXXX, TAXI INTO POS AND HOLD RWY 17L.' I ACKNOWLEDGED THE CLRNC WITH, 'TWIN CESSNA XXX, POS AND HOLD RWY 17L' AND BEGAN TO TAXI OUT TO RWY 17L. WHILE TAXIING INTO POS ON RWY 17L, I HEARD THE SAME CTLR TALKING TO SEVERAL ACFT INBOUND INCLUDING A TFC WATCH C172 THAT WAS ON A 3 MI FINAL AND CLRED TO LAND ON RWY 17L. ONCE IN POS ON RWY 17L, I WAITED FOR TKOF CLRNC KNOWING THAT THE TFC WATCH ACFT WAS BEARING DOWN ON ME AS I SAT ON THE RWY. FINALLY I WAS INSTRUCTED, 'TWIN CESSNA XXX, FLY RWY HDG. CLRED FOR TKOF RWY 17L.' I ACKNOWLEDGED, 'RWY HDG, CLRED TKOF RWY 17L, XXX' AND BEGAN MY TKOF ROLL. FROM THAT POINT THE FLT PROCEEDED WITHOUT FURTHER INCIDENT. LOOKING AT THIS INCIDENT, I DON'T KNOW WHAT I WOULD HAVE DONE DIFFERENTLY SAVE ASKING FOR VERIFICATION OF THE CLRNC ONTO RWY 17L AFTER THAT XMISSION FROM THE TWR WAS INTERFERED WITH BY AN UNKNOWN SOURCE. AT APA THE TWR WILL SCOLD YOU IF YOU RPT YOUR POS HOLDING SHORT OF A PARTICULAR RWY. PRESUMABLY, THE PRACTICE OF NOT RPTING POS SHORT OF A RWY IS USED TO DECREASE FREQ CONGESTION IN A VERY BUSY AIRSPACE, BUT I BELIEVE THAT IT SOMETIMES CAN CAUSE CONFUSION AND ERROR ON THE PART OF CTLR AND PLT ALIKE. AFTER BEING ASKED IF I WAS READY FOR TKOF AND AFTER WAITING 20-30 SECONDS SHORT OF THE HOLD LINE WITHOUT MOVING DOES AN INSTRUCTION TO 'HOLD SHORT' MAKE SENSE? I FEEL THAT THE CTLR SIMPLY MADE A MISTAKE. I ALSO BELIEVE THAT CTLR'S COMMENT THAT IT WAS 'NO PROB' THAT WE HAD MISCOMMUNICATED REINFORCES MY POS. EVERYONE MAKES MISTAKES OCCASIONALLY, BUT IN THIS INSTANCE THE MISTAKE COULD HAVE DEFINITELY BEEN A PROB.

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.