Narrative:

Aircraft X had been following aircraft Y in the traffic pattern. I cleared aircraft X number 2 to follow aircraft Y for the touch and go. Aircraft X reported an aircraft off their right and said they were initiating a go around. When I looked back to the final I saw one aircraft lower on final and aircraft X climbing out higher on the go around. Apparently aircraft X cut off aircraft Y which they had been following in the traffic pattern for some time. It did not appear to be any closer than the other 100 plus times [student] pilots had cut each other off in the pattern over the years. Usually I catch these events sooner. I must have been sorting out my upwind traffic. I try to as soon as possible get the departing pattern planes to find and follow the next plane ahead in the pattern so this doesn't happen. I have not had a chance to review the tapes as I was just called at home on my only day off and informed that some sort of near midair collision investigation had been started by the FBO which owns both planes involved.student pilots and instructors could do a better job of finding and following planes. Too many times student pilots are sent out [to] solo way before they are ready to be in a busy; complex traffic pattern. I think there was actually an instructor on aircraft X; but I am not sure. On the controller side; I would like to work fewer 6 day work weeks. [We are] short staffed and I have more mandatory 6 day weeks than not as of late; and there appears to be no end in sight. Sometimes it could occur and without tracking the planes visually out the window you would not see it coming as the stars fusion display is a terrible tool to have work busy VFR traffic at an airport with parallels separated by less than 1;000 feet. The old d-brite radar display was a far superior tool for the traffic we work. The d-brite would actually show two targets if two planes departed simultaneously stars will not. The algorithm that drives the fusion display is not compatible with our traffic and runway configuration.

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Original NASA ASRS Text

Title: FFZ Tower Controller observed an aircraft turn in front of another aircraft which it was supposed to follow.

Narrative: Aircraft X had been following Aircraft Y in the traffic pattern. I cleared Aircraft X number 2 to follow Aircraft Y for the touch and go. Aircraft X reported an aircraft off their right and said they were initiating a go around. When I looked back to the final I saw one aircraft lower on final and Aircraft X climbing out higher on the go around. Apparently Aircraft X cut off Aircraft Y which they had been following in the traffic pattern for some time. It did not appear to be any closer than the other 100 plus times [student] pilots had cut each other off in the pattern over the years. Usually I catch these events sooner. I must have been sorting out my upwind traffic. I try to as soon as possible get the departing pattern planes to find and follow the next plane ahead in the pattern so this doesn't happen. I have not had a chance to review the tapes as I was just called at home on my only day off and informed that some sort of NMAC investigation had been started by the FBO which owns both planes involved.Student pilots and instructors could do a better job of finding and following planes. Too many times student pilots are sent out [to] solo way before they are ready to be in a busy; complex traffic pattern. I think there was actually an instructor on Aircraft X; but I am not sure. On the controller side; I would like to work fewer 6 day work weeks. [We are] short staffed and I have more mandatory 6 day weeks than not as of late; and there appears to be no end in sight. Sometimes it could occur and without tracking the planes visually out the window you would not see it coming as the STARS FUSION display is a terrible tool to have work busy VFR traffic at an airport with parallels separated by less than 1;000 feet. The old D-Brite radar display was a far superior tool for the traffic we work. The D-Brite would actually show two targets if two planes departed simultaneously STARS will not. The algorithm that drives the FUSION display is not compatible with our traffic and runway configuration.

Data retrieved from NASA's ASRS site 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.