Pacific Southwest Airlines (PSA) was a low-cost airline in the United States headquartered in San Diego, California, that operated from 1949 to 1988. Founded by Kenny Friedkin and J. Floyd Andrews, it was the first substantial scheduled discount airline. PSA called itself "The World's Friendliest Airline" and painted a smile on the nose of its airplanes, the PSA Grinningbirds. The Los Angeles Times called PSA "practically the unofficial flag carrier airline of California for almost forty years."
For three quarters of its existence, PSA operated as a California intrastate airline. PSA's early success as an intrastate airline served as a model for Southwest Airlines, which did in Texas what PSA had done in California.