Narrative:

I was working ground control at baf tower. Small aircraft X landed on runway 20 and exited onto taxiway victor. I looked out at victor and noticed that small aircraft X had crossed the hold line for runway 20 correctly, but then crossed the hold short line for runway 15/33. I was unsure of the pilot's intentions (i.e., to hold short of 15/33 albeit over the hold line, or to cross runway 15/33). The pilot hadn't called me yet, but I immediately called the aircraft and instructed the pilot to hold his position. The pilot heard me and stopped. I then advised him he had crossed the line, and for future reference, he must remain behind the hold line for the runway he will be crossing. The pilot then made a 180 degree turn to reposition behind the hold line. Not wanting to complicate the situation, I advised the aircraft that repositioning wasn't necessary at that point and to just hold his position. Prior to this, I taxied an small aircraft Y to the ramp. I also noticed small aircraft west on final for runway 33 and that prompted my immediate action(south) with small aircraft X. The local controller had seen small aircraft X make its 180 degree on victor, while doing his runway scan prior to clearing an aircraft to land. He said he saw small aircraft X hold his position and he then went back to watching his other traffic. Shortly after the initial xmissions with small aircraft X (while he was on victor), an small aircraft Z exited at charlie taxiway, called me and asked for taxi instructions to transient parking. I was looking at small aircraft Z and I believe I instructed that pilot to taxi to the ramp. About that time, I was doing other tasks and had my attention diverted from small aircraft X on victor, who I last saw holding short of runway 15/33. Once I saw that the local controller had no aircraft landing on runway 33, I began to coordinate for crossing small aircraft X to cross runway 15/33 from victor taxiway to charlie taxiway. I looked up and saw small aircraft X was gone from victor. After looking all around the ramp, I saw small aircraft X parked below the tower at an FBO, and its occupants walking away from the aircraft. Believing a runway incursion had occurred, I called the FBO and had the pilot contact me in the tower to gather necessary information. When I explained what happened, the pilot claims he clearly heard taxi instructions for him. With a plane on short final he said he was surprised but figured we knew what we were doing. He said I instructed him to taxi 'anywhere he'd like.' I recall that exchange, but believed it was with small aircraft Z. The crossing occurred while the local controller and myself were scanning other areas, and we have no idea if runway separation was lost (hence a violation), or if the pilot misheard me, or if I did, in fact, give the wrong call sign, believing I was talking to small aircraft Z. The small aircraft west doing touch and go on runway 33 gave no indication of flying near another aircraft on the runway, nor did small aircraft X crossing the runway. Apparently, no emergency evasive action was taken by either pilot. I believe that the moderate traffic, combined with the fact that we were staffed by 2 controllers on that shift that allowed no breaks other than for swapping position may have contributed to the possible error. If I were at fault, I feel I may have been operating at less than peak ability. If the other pilot were at fault, I feel it was a result of not listening carefully enough to the call signs being used.

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Original NASA ASRS Text

Title: A TWR GND CTLR RPTS THAT HE MAY HAVE CROSSED AN SMA WITHOUT PROPER CLRNC, OR POSSIBLY THE SMA CROSSED THE RWY WITHOUT ANY CLRNC.

Narrative: I WAS WORKING GND CTL AT BAF TWR. SMA X LANDED ON RWY 20 AND EXITED ONTO TXWY VICTOR. I LOOKED OUT AT VICTOR AND NOTICED THAT SMA X HAD CROSSED THE HOLD LINE FOR RWY 20 CORRECTLY, BUT THEN CROSSED THE HOLD SHORT LINE FOR RWY 15/33. I WAS UNSURE OF THE PLT'S INTENTIONS (I.E., TO HOLD SHORT OF 15/33 ALBEIT OVER THE HOLD LINE, OR TO CROSS RWY 15/33). THE PLT HADN'T CALLED ME YET, BUT I IMMEDIATELY CALLED THE ACFT AND INSTRUCTED THE PLT TO HOLD HIS POS. THE PLT HEARD ME AND STOPPED. I THEN ADVISED HIM HE HAD CROSSED THE LINE, AND FOR FUTURE REF, HE MUST REMAIN BEHIND THE HOLD LINE FOR THE RWY HE WILL BE XING. THE PLT THEN MADE A 180 DEG TURN TO REPOSITION BEHIND THE HOLD LINE. NOT WANTING TO COMPLICATE THE SIT, I ADVISED THE ACFT THAT REPOSITIONING WASN'T NECESSARY AT THAT POINT AND TO JUST HOLD HIS POS. PRIOR TO THIS, I TAXIED AN SMA Y TO THE RAMP. I ALSO NOTICED SMA W ON FINAL FOR RWY 33 AND THAT PROMPTED MY IMMEDIATE ACTION(S) WITH SMA X. THE LCL CTLR HAD SEEN SMA X MAKE ITS 180 DEG ON VICTOR, WHILE DOING HIS RWY SCAN PRIOR TO CLRING AN ACFT TO LAND. HE SAID HE SAW SMA X HOLD HIS POS AND HE THEN WENT BACK TO WATCHING HIS OTHER TFC. SHORTLY AFTER THE INITIAL XMISSIONS WITH SMA X (WHILE HE WAS ON VICTOR), AN SMA Z EXITED AT CHARLIE TXWY, CALLED ME AND ASKED FOR TAXI INSTRUCTIONS TO TRANSIENT PARKING. I WAS LOOKING AT SMA Z AND I BELIEVE I INSTRUCTED THAT PLT TO TAXI TO THE RAMP. ABOUT THAT TIME, I WAS DOING OTHER TASKS AND HAD MY ATTN DIVERTED FROM SMA X ON VICTOR, WHO I LAST SAW HOLDING SHORT OF RWY 15/33. ONCE I SAW THAT THE LCL CTLR HAD NO ACFT LNDG ON RWY 33, I BEGAN TO COORDINATE FOR XING SMA X TO CROSS RWY 15/33 FROM VICTOR TXWY TO CHARLIE TXWY. I LOOKED UP AND SAW SMA X WAS GONE FROM VICTOR. AFTER LOOKING ALL AROUND THE RAMP, I SAW SMA X PARKED BELOW THE TWR AT AN FBO, AND ITS OCCUPANTS WALKING AWAY FROM THE ACFT. BELIEVING A RWY INCURSION HAD OCCURRED, I CALLED THE FBO AND HAD THE PLT CONTACT ME IN THE TWR TO GATHER NECESSARY INFO. WHEN I EXPLAINED WHAT HAPPENED, THE PLT CLAIMS HE CLRLY HEARD TAXI INSTRUCTIONS FOR HIM. WITH A PLANE ON SHORT FINAL HE SAID HE WAS SURPRISED BUT FIGURED WE KNEW WHAT WE WERE DOING. HE SAID I INSTRUCTED HIM TO TAXI 'ANYWHERE HE'D LIKE.' I RECALL THAT EXCHANGE, BUT BELIEVED IT WAS WITH SMA Z. THE XING OCCURRED WHILE THE LCL CTLR AND MYSELF WERE SCANNING OTHER AREAS, AND WE HAVE NO IDEA IF RWY SEPARATION WAS LOST (HENCE A VIOLATION), OR IF THE PLT MISHEARD ME, OR IF I DID, IN FACT, GIVE THE WRONG CALL SIGN, BELIEVING I WAS TALKING TO SMA Z. THE SMA W DOING TOUCH AND GO ON RWY 33 GAVE NO INDICATION OF FLYING NEAR ANOTHER ACFT ON THE RWY, NOR DID SMA X XING THE RWY. APPARENTLY, NO EMER EVASIVE ACTION WAS TAKEN BY EITHER PLT. I BELIEVE THAT THE MODERATE TFC, COMBINED WITH THE FACT THAT WE WERE STAFFED BY 2 CTLRS ON THAT SHIFT THAT ALLOWED NO BREAKS OTHER THAN FOR SWAPPING POS MAY HAVE CONTRIBUTED TO THE POSSIBLE ERROR. IF I WERE AT FAULT, I FEEL I MAY HAVE BEEN OPERATING AT LESS THAN PEAK ABILITY. IF THE OTHER PLT WERE AT FAULT, I FEEL IT WAS A RESULT OF NOT LISTENING CAREFULLY ENOUGH TO THE CALL SIGNS BEING USED.

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.