SAN Tower Controller reported an aircraft had turned into a non-movement area and needed assistance to get out; which caused a blockage on the taxiway and led to congestion related to the rerouting. The reporter noted that poor weather; insufficient markings; and lack of barricades contributed to the event.

Narrative

Aircraft X landed on Runway 9 and exited runway Taxiway D and switched to GC during poor weather conditions. Aircraft instructed to taxi to the Ramp via B; A2; A; B. Aircraft turned onto A1 a non-movement area. Aircraft stopped in Ramp area at A1 and called saying they made a wrong turn. This caused a blockage of the taxiway and required pushback onto the taxiway by a tug significantly increasing the workload as while this aircraft was stuck it required all Runway 9 arrivals to exit to the north requiring a runway crossing and then subsequently when switching back to Runway 27 the departures to cross to the north. It has been brought up many times to both Management and the Airport Authority that this is a multiple time occurrence due to the lack of barriers and/or proper markings. Recommendation: Either barricades need to be put up; markings need to be better or something needs to be done. The status quo of multiple aircraft ending up on a Ramp area without a Plan B besides blocking the one and only taxiway is unacceptable.