Narrative:

I was the ojti; conducting training on local control with a trainee controlling the traffic under my supervision/guidance. A PA32 was inbound to land; from the south approximately 10nm; VFR; conducting a practice approach to runway 1 circle to land runway 32. A C172 (skyhawk; single engine prop) was also inbound from the south; VFR; approximately 6 nm. The trainee issued instructions for C172 to be number 1; enter left base for runway 32. The trainee issued instructions to PA32 to be number 2 behind the skyhawk currently in the left base for runway 32 and to report traffic in sight. PA32 reported traffic in sight and was subsequently issued instructions to follow that traffic and report commencing circle to runway 32. PA32 reported commencing the circle. At this time; visual scan showed that spacing/sequence was going well and both aircraft were indicating 110 knots according to stars which also correlated with what we see visually. On final the number 1 aircraft reduced airspeed as expected; however visually there was still adequate spacing. On short final the trainee advised C172 'skyhawk; minimal time on the runway; please.' I agreed with my trainee's assessment that spacing would be close enough that it would be wise to encourage pilot cooperation to assist the number 2 aircraft with runway availability. The number 1 aircraft took longer than expected; touched down later than expected; passes intersection delta; then slowed to taxi speed still some distance from the next taxi way. As the ojti it was evident to me at this point that spacing was not going to work and upon visual scan; PA32 was now approaching 1/2 nm final. I allowed the trainee to make the next transmission and hoped that he/she would recognize that the spacing was not going to work. The trainees' next transmission was to issue instructions for C172 to exit at hotel. I verbally stated at this point that it wasn't going to work. Next; another pilot began transmitting on frequency requesting permission to enter class delta. At this point the PA32 was now on a short final (visually over highway 13 and the perimeter of the airfield.) as the ojti; I knew that time was short and it was at this point PA32 was over the airport perimeter in between transmissions I issued instructions to PA32 to 'go-around runway 32; traffic on the runway.' PA32 acknowledged my go-around; however his reply was garbled. Visually at the time of his reply; he still had not yet crossed threshold for runway 32; and through his garbled reply I could make out bits and pieces of his transmission and from what I understood he was telling me unable go around and that he was already committed to landing. No further transmission was made as PA32 crossed the threshold; touching down on the threshold and brought his plane to a taxi speed within the first 1;000 feet or less of runway space. Separation was clearly lost; however; as there was only approximately 1;500 feet of space between the 2 aircraft; both aircraft on the runway at the same time. After landing I discussed this issue a little further; traffic and time permitting we asked the pilot of PA32 to contact me on another frequency and we asked if he heard us issue the go-around. The pilot agreed that he did hear us issue the go-around; however he felt that it was too late for him to safely go around and he decided that it was safer for him to land his plane because he could see the aircraft in front of him and he stated that he knew he could 'stop on a dime.' recommendation; as the ojti; although I realize that we provided legal control instructions to go-around prior to PA32 reaching the threshold; I recognize that there are things that could have been done differently. For example as the ojti I could have chosen to issue the go-around further in advance. Also; with the PA32 radios being somewhat scratchy/garbled I could have addressed the poor radio communication upon initial contact with the pilot in order to raise the pilot's awarenessthat we may have difficulty communicating. Both pilot's had each other in sight and were sequenced well in advance; the number 2 pilot could have also initiated a go-around or took other actions to affect spacing. Also; as I talked to the pilot of PA32; he admitted that he understood we issued a go-around and that he heard me clearly; however he felt it 'wasn't fair' and 'wasn't good' and that it was 'safer to land.' I believe that the garbled radio was not an issue in this particular situation; however in future situations I would take extra measure to ensure that the pilot can hear my instructions and that I can clearly hear their reply; prior to the aircraft reaching short final.

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Original NASA ASRS Text

Title: Local Controller providing OJT described a loss of runway separation event when an aircraft on short final failed to comply with go around instructions.

Narrative: I was the OJTI; conducting training on Local Control with a trainee controlling the traffic under my supervision/guidance. A PA32 was inbound to land; from the South approximately 10nm; VFR; conducting a practice approach to Runway 1 circle to land Runway 32. A C172 (Skyhawk; single engine prop) was also inbound from the South; VFR; approximately 6 nm. The trainee issued instructions for C172 to be number 1; enter left base for Runway 32. The trainee issued instructions to PA32 to be number 2 behind the Skyhawk currently in the left base for Runway 32 and to report traffic in sight. PA32 reported traffic in sight and was subsequently issued instructions to follow that traffic and report commencing circle to Runway 32. PA32 reported commencing the circle. At this time; visual scan showed that spacing/sequence was going well and both aircraft were indicating 110 knots according to STARS which also correlated with what we see visually. On final the number 1 aircraft reduced airspeed as expected; however visually there was still adequate spacing. On short final the trainee advised C172 'Skyhawk; minimal time on the runway; please.' I agreed with my trainee's assessment that spacing would be close enough that it would be wise to encourage pilot cooperation to assist the number 2 aircraft with runway availability. The number 1 aircraft took longer than expected; touched down later than expected; passes intersection Delta; then slowed to taxi speed still some distance from the next taxi way. As the OJTI it was evident to me at this point that spacing was not going to work and upon visual scan; PA32 was now approaching 1/2 nm final. I allowed the trainee to make the next transmission and hoped that he/she would recognize that the spacing was not going to work. The trainees' next transmission was to issue instructions for C172 to exit at Hotel. I verbally stated at this point that it wasn't going to work. Next; another pilot began transmitting on frequency requesting permission to enter Class Delta. At this point the PA32 was now on a short final (visually over highway 13 and the perimeter of the airfield.) As the OJTI; I knew that time was short and it was at this point PA32 was over the airport perimeter in between transmissions I issued instructions to PA32 to 'Go-Around Runway 32; traffic on the runway.' PA32 acknowledged my go-around; however his reply was garbled. Visually at the time of his reply; he still had not yet crossed threshold for Runway 32; and through his garbled reply I could make out bits and pieces of his transmission and from what I understood he was telling me unable go around and that he was already committed to landing. No further transmission was made as PA32 crossed the threshold; touching down on the threshold and brought his plane to a taxi speed within the first 1;000 feet or less of runway space. Separation was clearly lost; however; as there was only approximately 1;500 feet of space between the 2 aircraft; both aircraft on the runway at the same time. After landing I discussed this issue a little further; traffic and time permitting we asked the pilot of PA32 to contact me on another frequency and we asked if he heard us issue the go-around. The pilot agreed that he did hear us issue the go-around; however he felt that it was too late for him to safely go around and he decided that it was safer for him to land his plane because he could see the aircraft in front of him and he stated that he knew he could 'stop on a dime.' Recommendation; as the OJTI; although I realize that we provided legal control instructions to Go-Around prior to PA32 reaching the threshold; I recognize that there are things that could have been done differently. For example as the OJTI I could have chosen to issue the Go-Around further in advance. Also; with the PA32 radios being somewhat scratchy/garbled I could have addressed the poor radio communication upon initial contact with the pilot in order to raise the pilot's awarenessthat we may have difficulty communicating. Both pilot's had each other in sight and were sequenced well in advance; the number 2 pilot could have also initiated a go-around or took other actions to affect spacing. Also; as I talked to the pilot of PA32; he admitted that he understood we issued a go-around and that he heard me clearly; however he felt it 'wasn't fair' and 'wasn't good' and that it was 'safer to land.' I believe that the garbled radio was not an issue in this particular situation; however in future situations I would take extra measure to ensure that the pilot can hear my instructions and that I can clearly hear their reply; prior to the aircraft reaching short final.

Data retrieved from NASA's ASRS site as of July 2013 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.