Pacific Southwest Airlines (PSA) was a low-cost US airline headquartered in San Diego, California, that operated from 1949 to 1988. 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."

California Central Airlines (CCA) was a post-war American scheduled price-focused intrastate airline based at Burbank, California, the most prominent airline associated with Charles C. Sherman. CCA slightly preceded, and during its existence was bigger than, its contemporary and competitor, Pacific Southwest Airlines (PSA). The core route of both airlines was from Los Angeles to the San Francisco Bay Area.