Narrative:

During the time of the event I was working ground control; there was training on local control; and a supervisor working the desk. Aircraft X requested push back and tow clearance to the guard ramp. I had no traffic on ground control so I approved the tow. A few minutes after I approved the tow a crash fire rescue equipment [call for release] strip printed from the fdio [flight data input/output] so I went to update the sia [system information area]. At this time aircraft X was established on taxiway sierra and approaching foxtrot from west to east. While I was updating the sia the local controller (local control) turned aircraft Y off runway 26L at foxtrot. There was no traffic following aircraft Y on final and there was only aircraft Z holding short of runway 26L for departure.there was no imminent reason why the local control couldn't have either turned aircraft Y of the runway at the end at taxiway sierra or took the aircraft to the north side of the airport. The local control also admitted he saw the aircraft under tow and still turned the aircraft off at taxiway foxtrot. The trainer had his back turned to the west and was facing east and didn't see the aircraft under tow. I believe because the majority of the time [we] turn aircraft of at taxiway foxtrot especially aircraft Y type; neither the trainer or the supervisor was on alert and both of them had there backs turned. During the time I was updating the board aircraft Y called for taxi to parking. When I looked up; aircraft Y was on taxiway foxtrot short of taxiway sierra facing south. I immediately reached out to aircraft X and instructed them to hold position. I informed both local control and the supervisor of the impeding situation. I looked at locals traffic to see if maybe we could turn aircraft Y back onto the runway to avoid aircraft X but local control had already cleared aircraft Z for takeoff. Concurrently; aircraft X read back 'roger; hold short of foxtrot.' I immediately responded negative; hold position. Aircraft X kept moving and pushed passed foxtrot and held short of foxtrot on the east side. When aircraft X passed foxtrot; aircraft X's wing passed above aircraft Y. Aircraft Y reported on frequency that the aircraft X's wing cleared her aircraft by only 3 feet. I informed the supervisor who was also monitoring ground and local frequencies; and I asked her to file an mor. The supervisor told me a mor did not need to be filed. I also asked the supervisor if I needed to file a report and she said no because this was not a reportable event. Two days later the supervisor informed me that she had to file an mor and that I should file a report. I informed her that at the time I didn't realize that there was a runway incursion because aircraft Z departed and aircraft Y was not pass the hold bars. She said there was no runway incursion because aircraft Y crossed the runway edge (white line) and the aircraft is small enough to fit between the runway edge and taxiway sierra. I would recommend that all parties involved would pay closer attention to the operation as a whole. I believe that the problem was created by local control. Had the trainer been paying attention; I believe he would have instructed the trainee to turn the aircraft off at the end reference aircraft X and there wouldn't have been an issue at all.

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Original NASA ASRS Text

Title: ONT Tower Controller describes a situation where an aircraft under tow was told to stop; but reads back different instructions. As a result; the aircraft ended up being towed over a smaller aircraft and missing it by three feet.

Narrative: During the time of the event I was working ground control; there was training on local control; and a supervisor working the desk. Aircraft X requested push back and tow clearance to the guard ramp. I had no traffic on ground control so I approved the tow. A few minutes after I approved the tow a CFR [Call For Release] strip printed from the FDIO [Flight Data Input/Output] so I went to update the SIA [System Information Area]. At this time Aircraft X was established on taxiway Sierra and approaching Foxtrot from west to east. While I was updating the SIA the Local Controller (LC) turned Aircraft Y off runway 26L at Foxtrot. There was no traffic following Aircraft Y on final and there was only Aircraft Z holding short of runway 26L for departure.There was no imminent reason why the LC couldn't have either turned Aircraft Y of the runway at the end at taxiway Sierra or took the aircraft to the north side of the airport. The LC also admitted he saw the aircraft under tow and still turned the aircraft off at taxiway foxtrot. The trainer had his back turned to the west and was facing east and didn't see the aircraft under tow. I believe because the majority of the time [we] turn aircraft of at taxiway Foxtrot especially Aircraft Y type; neither the trainer or the supervisor was on alert and both of them had there backs turned. During the time I was updating the board Aircraft Y called for taxi to parking. When I looked up; Aircraft Y was on taxiway foxtrot short of taxiway Sierra facing south. I immediately reached out to Aircraft X and instructed them to hold position. I informed both LC and the supervisor of the impeding situation. I looked at locals traffic to see if maybe we could turn Aircraft Y back onto the runway to avoid Aircraft X but LC had already cleared Aircraft Z for takeoff. Concurrently; Aircraft X read back 'Roger; hold short of foxtrot.' I immediately responded negative; hold position. Aircraft X kept moving and pushed passed foxtrot and held short of foxtrot on the east side. When Aircraft X passed foxtrot; Aircraft X's wing passed above Aircraft Y. Aircraft Y reported on frequency that the Aircraft X's wing cleared her aircraft by only 3 feet. I informed the supervisor who was also monitoring ground and local frequencies; and I asked her to file an MOR. The supervisor told me a MOR did not need to be filed. I also asked the supervisor if I needed to file a report and she said no because this was not a reportable event. Two days later the supervisor informed me that she had to file an MOR and that I should file a report. I informed her that at the time I didn't realize that there was a runway incursion because Aircraft Z departed and Aircraft Y was not pass the hold bars. She said there was no runway incursion because Aircraft Y crossed the runway edge (white line) and the aircraft is small enough to fit between the runway edge and taxiway Sierra. I would recommend that all parties involved would pay closer attention to the operation as a whole. I believe that the problem was created by LC. Had the trainer been paying attention; I believe he would have instructed the trainee to turn the aircraft off at the end reference Aircraft X and there wouldn't have been an issue at all.

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.