Narrative:

Operating as a crew of 2 as a scheduled part 121 flight from mwa-ZZZ. Upon calling for taxi and requesting clearance; mwa ground control advised us to taxi to runway 2 via the appropriate txwys and clearance was on request. We remained on the ground frequency awaiting the IFR clearance. After an uneventful taxi to runway 2 we were holding short of the runway at the departure end when the clearance became available. ATC read us the clearance which was as filed and it was read back. After a review of the clearance; the before takeoff checklist was completed and we switched frequencys to the tower and advised ready for takeoff. Prior to this point; we were only monitoring the ground frequency and did not hear any tower xmissions. The tower cleared us for takeoff and 'cleared on course.' as is consistent with company procedures; the first officer visually cleared the right side of the aircraft and I visually cleared the left and this was acknowledged verbally. At this time (about 3-5 ft across the hold short line and prior to entering the runway itself) I denoted traffic on the TCAS display +400 ft on final for our runway. I immediately stopped the aircraft and simultaneously inquired with the tower as well as visually began scanning the final approach path again. I then saw a small single engine GA aircraft on final (later seen to be a bonanza) without a landing light making him a 'specification' when looking hard. The tower advised us to hold short of the runway and I replied that we were already across the hold short line. The bonanza was then heard on the tower advising he was initiating a go around. The tower never gave him a go around instruction. We were subsequently cleared for takeoff again and the tower stated 'sorry about that.' there was no further incident. In this occurrence the company procedures for maintaining vigilance entering a runway were effective in preventing more of a conflict than that which occurred. The bonanza pilot's self initiation of a go around was the right move; however; it would have been better had the other pilot been proactive in an inquiry of the tower after hearing us cleared for takeoff on his landing runway. The tower was in error by clearing us for takeoff.

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Original NASA ASRS Text

Title: ACR DEP FROM MWA WAS CLRED FOR TKOF; CROSSED HOLD LINE; ONLY TO SEE ACFT ON FINAL EXECUTING GAR; TWR ADMITTED ERROR; NO OPERROR RECORDED.

Narrative: OPERATING AS A CREW OF 2 AS A SCHEDULED PART 121 FLT FROM MWA-ZZZ. UPON CALLING FOR TAXI AND REQUESTING CLRNC; MWA GND CTL ADVISED US TO TAXI TO RWY 2 VIA THE APPROPRIATE TXWYS AND CLRNC WAS ON REQUEST. WE REMAINED ON THE GND FREQ AWAITING THE IFR CLRNC. AFTER AN UNEVENTFUL TAXI TO RWY 2 WE WERE HOLDING SHORT OF THE RWY AT THE DEP END WHEN THE CLRNC BECAME AVAILABLE. ATC READ US THE CLRNC WHICH WAS AS FILED AND IT WAS READ BACK. AFTER A REVIEW OF THE CLRNC; THE BEFORE TKOF CHKLIST WAS COMPLETED AND WE SWITCHED FREQS TO THE TWR AND ADVISED READY FOR TKOF. PRIOR TO THIS POINT; WE WERE ONLY MONITORING THE GND FREQ AND DID NOT HEAR ANY TWR XMISSIONS. THE TWR CLRED US FOR TKOF AND 'CLRED ON COURSE.' AS IS CONSISTENT WITH COMPANY PROCS; THE FO VISUALLY CLRED THE R SIDE OF THE ACFT AND I VISUALLY CLRED THE L AND THIS WAS ACKNOWLEDGED VERBALLY. AT THIS TIME (ABOUT 3-5 FT ACROSS THE HOLD SHORT LINE AND PRIOR TO ENTERING THE RWY ITSELF) I DENOTED TFC ON THE TCAS DISPLAY +400 FT ON FINAL FOR OUR RWY. I IMMEDIATELY STOPPED THE ACFT AND SIMULTANEOUSLY INQUIRED WITH THE TWR AS WELL AS VISUALLY BEGAN SCANNING THE FINAL APCH PATH AGAIN. I THEN SAW A SMALL SINGLE ENG GA ACFT ON FINAL (LATER SEEN TO BE A BONANZA) WITHOUT A LNDG LIGHT MAKING HIM A 'SPEC' WHEN LOOKING HARD. THE TWR ADVISED US TO HOLD SHORT OF THE RWY AND I REPLIED THAT WE WERE ALREADY ACROSS THE HOLD SHORT LINE. THE BONANZA WAS THEN HEARD ON THE TWR ADVISING HE WAS INITIATING A GAR. THE TWR NEVER GAVE HIM A GAR INSTRUCTION. WE WERE SUBSEQUENTLY CLRED FOR TKOF AGAIN AND THE TWR STATED 'SORRY ABOUT THAT.' THERE WAS NO FURTHER INCIDENT. IN THIS OCCURRENCE THE COMPANY PROCS FOR MAINTAINING VIGILANCE ENTERING A RWY WERE EFFECTIVE IN PREVENTING MORE OF A CONFLICT THAN THAT WHICH OCCURRED. THE BONANZA PLT'S SELF INITIATION OF A GAR WAS THE RIGHT MOVE; HOWEVER; IT WOULD HAVE BEEN BETTER HAD THE OTHER PLT BEEN PROACTIVE IN AN INQUIRY OF THE TWR AFTER HEARING US CLRED FOR TKOF ON HIS LNDG RWY. THE TWR WAS IN ERROR BY CLRING US FOR TKOF.

Data retrieved from NASA's ASRS site as of May 2009 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.