Light Transport; High Wing; 2 Turboprop Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10
Situational Awareness
Conflict Ground Conflict; Less Severe; Ground Event / Encounter Other / Unknown
Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure
Aircraft X exited Runway 28L and taxied via TWY T to gate XY. At about the same time Aircraft Y started taxiing out of the alley to Runway 28L via B3. Aircraft X was well ahead of Aircraft Y and normally would not be a factor; so I turned my attention elsewhere. Problem is that Aircraft X was delayed on the taxiway waiting for a marshaller; and Aircraft Y passed by him near the area where taxiways B and T converge before Aircraft X moved clear of the taxiway. The Aircraft X pilot claimed that Aircraft Y's wing passed over his wing.I didn't notice it until they were almost next to each other. Traffic had just slowed down after being a little busy and I let my guard down. I need to keep up my scan when traffic slows. When I did notice it; I could have told Aircraft Y to stop; but it looked like they had enough room to pass. It didn't seem worth the risk to have him slam on his brakes and possibly injure a flight attendant. I issued a caution to Aircraft Y; wasn't much else I could do at that point.I was a little surprised Aircraft Y didn't stop on his own and wait until there was more room. However; a pilot behind him had an excellent view and later told Aircraft Y there was plenty of room. It wouldn't hurt if Aircraft X had given me a heads up when he realized he would be delayed on the taxiway waiting for a marshaller. I later spoke to the Aircraft X pilot on the phone. He was cool about it.
PDX Tower Controller reported a large aircraft's wing went over a smaller aircraft; claimed by the smaller aircraft. Smaller aircraft was delayed going into the alley way and larger aircraft continued taxiing. Another aircraft said there was plenty of room.