Sfo tower controller reported a medium large transport aircraft had a taxiway incursion resulting in...

Narrative:

Aircraft X exited runway 28 left at tango and said forty for the gate. After clarifying forty minutes for the gate or forty past the hour; it was about twelve minutes to wait; I gave them taxi via B hold short of Q on their right hand side (runway exit). When I looked at aircraft Y rolling out on runway 28 left to exit Q; while giving a pushback clearance to another aircraft at gate xx; aircraft X was right in the middle of the intersection; and aircraft Y had to make an evasive maneuver to continue back on runway 28 left to the next exit. I told aircraft X they were supposed to hold short of Q. They were then given B to the ramp as I no longer had a way to hold them with a blocked by pushback aircraft and taxiing aircraft all off of their left. Pilot conformance with instructions would have helped both of us as I hate to send them all of the way back to the ramp if I can stage the aircraft for a pushback far enough to allow them in; which eventually occurred. It just took them deeper in towards the ramp and a turn around. If there seems to be a hint of unfamiliarity; I try to help the pilots out to make sure we are on the same page. I did not get that during this event.

Original NASA ASRS Text

Title: SFO Tower Controller reported a Medium Large Transport aircraft had a taxiway incursion resulting in a Large Transport aircraft taking evasive action.

Narrative: Aircraft X exited runway 28 Left at Tango and said forty for the gate. After clarifying forty minutes for the gate or forty past the hour; it was about twelve minutes to wait; I gave them taxi via B hold short of Q on their right hand side (runway exit). When I looked at Aircraft Y rolling out on Runway 28 Left to exit Q; while giving a pushback clearance to another aircraft at gate XX; Aircraft X was right in the middle of the intersection; and Aircraft Y had to make an evasive maneuver to continue back on Runway 28 L to the next exit. I told Aircraft X they were supposed to hold short of Q. They were then given B to the ramp as I no longer had a way to hold them with A blocked by pushback aircraft and taxiing aircraft all off of their left. Pilot conformance with instructions would have helped both of us as I hate to send them all of the way back to the ramp if I can stage the aircraft for a pushback far enough to allow them in; which eventually occurred. It just took them deeper in towards the ramp and a turn around. If there seems to be a hint of unfamiliarity; I try to help the pilots out to make sure we are on the same page. I did not get that during this event.

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.

Attributes
ACN	1674096
Time
Date	201908
Local Time Of Day	1201-1800
Place
Locale Reference	SFO.Tower
State Reference	CA
Aircraft 1
Make Model Name	Medium Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Route In Use	None
Flight Plan	IFR
Aircraft 2
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Ground
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 19.7
Events
Anomaly	Conflict Ground Conflict Critical Deviation - Procedural Clearance Ground Incursion Runway Ground Incursion Taxiway

Sfo tower controller reported a medium large transport aircraft had a taxiway incursion resulting in a large transport aircraft taking evasive action.