Narrative:

I was working a busy and complex session on local south. There were numerous itinerant arrivals as well as multiple pattern players that were either landing and ending their pattern work or departing the area. There was also a few aircraft waiting to depart. A PC12 called inbound from the west of chino. I knew he parked on the north side of the airport but I had multiple aircraft tagged up coming to runway 26R; the north runway; from the north and east. I cleared him to land runway 26L and he did with out incident. When he exited the runway; he turned north; between the parallel runways. I instructed him to hold short of runway 26R and remain on my frequency; which is standard procedure at chino. He read back 'hold short runway 26R; PC12' I believe that is an improper read back as it only had the final two digits of his call sign instead of three. I only realized it was a bad read back because I had to pull the voice recorded data for the events that followed. The PC12 did as he was instructed and held short of runway 26R without incident; but I failed to get a proper read back from him. As this was happening I had multiple other aircraft demanding my attention. One of these was the C400; inbound from the south. I knew the C400 parked on the north side of the airport but due to the traffic already sequenced to runway 26R I issued him a left base entry for runway 26L. He read this back properly with the runway identifier. A minute or so later after dealing with other aircraft I sequenced the C400 to follow an aircraft in left closed traffic and cleared him to land. He read this back correctly with runway identifier. By this point two aircraft were waiting to depart runway 26R; the second of which was the C172. There were also three aircraft landing runway 26R. I then issued the C400 an updated position of the aircraft he was to follow. I did not include anything about the runway in this transmission; and the C400 responded that he did not have the aircraft in sight. There was sufficient spacing between the second arrival and the third to clear the two aircraft waiting to depart for take off with reduced same runway separation. Had everything gone as planned the C400 would have landed on runway 26L and would have taxied behind the PC12. They would have been able to cross runway 26R after the third arrival. Things did not go as planned as the C400 turned final to land on runway 26R; and I did not see he had done so. As I scanned short final and the runway before clearing the C172 for take off; I saw the C400 but I did not realize his mistake. I cleared the C172 for take off as I double checked my same runway separation with the first departure and once again scanned short final. The C172 read back his clearance; and as he had been waiting to leave for about 3 minutes; started moving immediately. The C172 crossed the hold bar of runway 26R as I realized the C400 was less then a quarter mile on final; lined up for the wrong runway on his final descent to the runway. I immediately issued go around instructions for the C400 twice. I also told the C172 to stop. I used improper phraseology here regarding the C172 I believe my actual words were 'C400; go around. C400; go around C172 stop!; C400; go around!' the C172 heard the urgency in my words and stopped before crossing the white runway edge lines but was in the safety area. I never properly cancelled his take off clearance or told him to hold short. The C400 started his go around climb prior to the threshold but did not verbally acknowledge the go around until he was passed the threshold and about 200 ft up in his climb. I was tying up the frequency shouting for him to go around so I think that was the earliest the C400 could respond and verbally acknowledge my instructions. I am fairly certain had I not noticed and taken corrected action the C400 would have landed on top of the C172 as the C172 lined up for his takeoff roll. I then resolved the remaining situation re-sequenced andcleared the C400 to land after the third arrival; who was still on downwind. I re-issued a takeoff clearance for the C172; once the C400 was no longer a factor. I gave the position to another controller using proper procedure and checked the tapes of the incident. The C400 read back all of my instructions but failed to follow them; as I have related. Regarding the PC12; I just need to work harder on analyzing read backs. I also think more pilot literature; i.e. Safety bulletins; stressing the importance of a read back with three digits of the call sign would be helpful. I believe the pilot of the PC12 believed he gave a good read back. He also did do as instructed to obviously he understood my instructions. As for the C400 I am not sure what can be done. This was an honest mistake. He wanted to land runway 26R. He was used to landing that runway most often. He was instructed to land the parallel runway due to traffic and read it back. Yet he did what he wanted to do rather then what he was instructed to do and lined up for the wrong runway. I wish I had noticed the problem sooner and either had him land before clearing the C172 to depart or issue him a go around/corrective instruction at an earlier point. However our radar does not have that level of clarity and the visual difference out the window of a small aircraft landing runway 26R and one landing runway 26L is pretty small until they get within half a mile of the runway. I will be much more careful for that in the future; but there was nothing in my mind to indicate a problem. So when I saw the C400 on final for the first time out the window I thought he was doing as instructed and it was only on my second evaluation that I realized there was a problem. I will try to do better in the future; but I believe reevaluating and spotting these situations is what I am there for. And I am glad I did because I do think it could have resulted in a collision had I not sent the C400 around. Regarding the improper phraseology I used to stop the C172; I let my emotions over a very scary situation override my training. I knew the proper phraseology and have used it before; but I did not use it. Instead I used the clearer and direct 'stop!' the C172 got the message and stopped. Again I am not sure what I could do better other then being more experience with dealing with dangerous situations. The more of them I see; the better I get at overriding my emotions and following procedure; however I would much rather not experience dangerous situations in the first place.

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Original NASA ASRS Text

Title: CNO Controller described a wrong parallel runway landing attempt requiring a last minute go around instruction; the reporter providing a number of improvements expected as more experience is gained.

Narrative: I was working a busy and complex session on Local South. There were numerous itinerant arrivals as well as multiple pattern players that were either landing and ending their pattern work or departing the area. There was also a few aircraft waiting to depart. A PC12 called inbound from the west of Chino. I knew he parked on the north side of the airport but I had multiple aircraft tagged up coming to Runway 26R; the north runway; from the north and east. I cleared him to land Runway 26L and he did with out incident. When he exited the runway; he turned north; between the parallel runways. I instructed him to hold short of Runway 26R and remain on my frequency; which is standard procedure at Chino. He read back 'Hold short Runway 26R; PC12' I believe that is an improper read back as it only had the final two digits of his call sign instead of three. I only realized it was a bad read back because I had to pull the voice recorded data for the events that followed. The PC12 did as he was instructed and held short of Runway 26R without incident; but I failed to get a proper read back from him. As this was happening I had multiple other aircraft demanding my attention. One of these was the C400; inbound from the south. I knew the C400 parked on the north side of the airport but due to the traffic already sequenced to Runway 26R I issued him a left base entry for Runway 26L. He read this back properly with the runway identifier. A minute or so later after dealing with other aircraft I sequenced the C400 to follow an aircraft in left closed traffic and cleared him to land. He read this back correctly with runway identifier. By this point two aircraft were waiting to depart Runway 26R; the second of which was the C172. There were also three aircraft landing Runway 26R. I then issued the C400 an updated position of the aircraft he was to follow. I did not include anything about the runway in this transmission; and the C400 responded that he did not have the aircraft in sight. There was sufficient spacing between the second arrival and the third to clear the two aircraft waiting to depart for take off with reduced same runway separation. Had everything gone as planned the C400 would have landed on Runway 26L and would have taxied behind the PC12. They would have been able to cross Runway 26R after the third arrival. Things did not go as planned as the C400 turned final to land on Runway 26R; and I did not see he had done so. As I scanned short final and the runway before clearing the C172 for take off; I saw the C400 but I did not realize his mistake. I cleared the C172 for take off as I double checked my same runway separation with the first departure and once again scanned short final. The C172 read back his clearance; and as he had been waiting to leave for about 3 minutes; started moving immediately. The C172 crossed the hold bar of Runway 26R as I realized the C400 was less then a quarter mile on final; lined up for the wrong runway on his final descent to the runway. I immediately issued go around instructions for the C400 twice. I also told the C172 to stop. I used improper phraseology here regarding the C172 I believe my actual words were 'C400; Go around. C400; Go around C172 STOP!; C400; Go around!' The C172 heard the urgency in my words and stopped before crossing the white runway edge lines but was in the safety area. I never properly cancelled his take off clearance or told him to hold short. The C400 started his go around climb prior to the threshold but did not verbally acknowledge the go around until he was passed the threshold and about 200 FT up in his climb. I was tying up the frequency shouting for him to go around so I think that was the earliest the C400 could respond and verbally acknowledge my instructions. I am fairly certain had I not noticed and taken corrected action the C400 would have landed on top of the C172 as the C172 lined up for his takeoff roll. I then resolved the remaining situation re-sequenced andcleared the C400 to land after the third arrival; who was still on downwind. I re-issued a takeoff clearance for the C172; once the C400 was no longer a factor. I gave the position to another Controller using proper procedure and checked the tapes of the incident. The C400 read back all of my instructions but failed to follow them; as I have related. Regarding the PC12; I just need to work harder on analyzing read backs. I also think more pilot literature; I.E. safety bulletins; stressing the importance of a read back with three digits of the call sign would be helpful. I believe the pilot of the PC12 believed he gave a good read back. He also did do as instructed to obviously he understood my instructions. As for the C400 I am not sure what can be done. This was an honest mistake. He wanted to land Runway 26R. He was used to landing that runway most often. He was instructed to land the parallel runway due to traffic and read it back. Yet he did what he wanted to do rather then what he was instructed to do and lined up for the wrong runway. I wish I had noticed the problem sooner and either had him land before clearing the C172 to depart or issue him a go around/corrective instruction at an earlier point. However our RADAR does not have that level of clarity and the visual difference out the window of a small aircraft landing Runway 26R and one landing Runway 26L is pretty small until they get within half a mile of the runway. I will be much more careful for that in the future; but there was nothing in my mind to indicate a problem. So when I saw the C400 on final for the first time out the window I thought he was doing as instructed and it was only on my second evaluation that I realized there was a problem. I will try to do better in the future; but I believe reevaluating and spotting these situations is what I am there for. And I am glad I did because I do think it could have resulted in a collision had I not sent the C400 around. Regarding the improper phraseology I used to stop the C172; I let my emotions over a very scary situation override my training. I knew the proper phraseology and have used it before; but I did not use it. Instead I used the clearer and direct 'STOP!' The C172 got the message and stopped. Again I am not sure what I could do better other then being more experience with dealing with dangerous situations. The more of them I see; the better I get at overriding my emotions and following procedure; however I would much rather not experience dangerous situations in the first place.

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.