Narrative:

I was working the local control position when a cessna called for takeoff (alfa taxiway east side). I told the pilot to 'hold short of runway 01' and the pilot read back the hold short instructions. The pilot had previously requested VFR flight following from the ground controller; but switched over to the local control frequency prior to receiving his clearance. I read the pilot his clearance for the flight following and concluded with an instruction to 'continue to hold short runway 01'; after he had already once acknowledged the hold short instructions. The pilot was obviously worried about entering the bravo airspace after departure and questioned whether his altitude would keep him out of it. I acknowledged his question and told the pilot to 'read back hold short runway 01'. This was the third time I addressed the pilot to hold short. As the pilot was reading back the instructions; I was watching several other things on radar and had some tower feedback in my other ear. What I heard was 'hold (garbled) runway 01'. I recognized the unclear read back but did not see how this could be anything other than the standard hold short phraseology. I had already spent a lot of time with this pilot and felt I needed to move on to other things; but still being vigilant to his movement. Later; after reviewing the tapes the pilot had actually read back 'hold on runway 01'. I observed the cessna taxi onto the runway with a hawker on final. I cancelled the hawkers landing clearance and issued a go around. I asked the cessna why he was on the runway and observed him exit the runway. He thought he had clearance onto the runway. The hawker was on the go-around prior to reaching the runway; so there was no loss of separation. After the preliminary investigation it was determined that the actual call sign for the cessna aircraft was different although the pilot never used the correct call sign in any communications with the ground or local controller. Also; during the preliminary interview with the pilot he admitted that he recognized that 'hold on runway 01' was not the standard phraseology for position and hold but decided not to question it. Obviously; there was read back/hear back issues for both controller and pilot in this situation. Recommendation; don't assume too much! Even though the pilot was told three times to 'hold short'; it didn't happen. I recognized at the time that the read back was not clear; but I still should have gone back a 4th time and reiterated the hold short. Use headsets more frequently even though you may not feel it justified at the time. It's easy to get into the flow of working and planning traffic; but must not get caught in the trap of keep moving on to the next thing when something just doesn't fit right. Be more cognizant of read back and hear back from both pilot and controller perspectives. Better speakers and noise dampening ceilings in the operational areas.

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Original NASA ASRS Text

Title: MKC local controller described a very confused read back hear back event resulting in an aircraft taxiing onto the runway unexpectedly and a required go around instruction for landing traffic.

Narrative: I was working the Local Control position when a Cessna called for takeoff (Alfa Taxiway East side). I told the pilot to 'Hold Short of Runway 01' and the pilot read back the hold short instructions. The pilot had previously requested VFR flight following from the Ground Controller; but switched over to the Local Control frequency prior to receiving his clearance. I read the pilot his clearance for the flight following and concluded with an instruction to 'continue to Hold Short Runway 01'; after he had already once acknowledged the hold short instructions. The pilot was obviously worried about entering the Bravo Airspace after departure and questioned whether his altitude would keep him out of it. I acknowledged his question and told the pilot to 'Read Back Hold Short Runway 01'. This was the third time I addressed the pilot to Hold Short. As the pilot was reading back the instructions; I was watching several other things on RADAR and had some tower feedback in my other ear. What I heard was 'Hold (garbled) RUNWAY 01'. I recognized the unclear read back but did not see how this could be anything other than the standard Hold Short phraseology. I had already spent a lot of time with this pilot and felt I needed to move on to other things; but still being vigilant to his movement. Later; after reviewing the tapes the pilot had actually read back 'Hold on Runway 01'. I observed the Cessna taxi onto the runway with a Hawker on final. I cancelled the Hawkers landing clearance and issued a go around. I asked the Cessna why he was on the runway and observed him exit the runway. He thought he had clearance onto the runway. The Hawker was on the go-around prior to reaching the runway; so there was no loss of separation. After the preliminary investigation it was determined that the actual call sign for the Cessna aircraft was different although the pilot never used the correct call sign in any communications with the Ground or Local Controller. Also; during the preliminary interview with the pilot he admitted that he recognized that 'Hold on Runway 01' was not the standard phraseology for Position and Hold but decided not to question it. Obviously; there was read back/hear back issues for both controller and pilot in this situation. Recommendation; don't assume too much! Even though the pilot was told three times to 'Hold Short'; it didn't happen. I recognized at the time that the read back was not clear; but I still should have gone back a 4th time and reiterated the Hold Short. Use headsets more frequently even though you may not feel it justified at the time. It's easy to get into the flow of working and planning traffic; but must not get caught in the trap of keep moving on to the next thing when something just doesn't fit right. Be more cognizant of read back and hear back from both pilot and controller perspectives. Better speakers and noise dampening ceilings in the operational areas.

Data retrieved from NASA's ASRS site as of April 2012 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.