Pacific Southwest Airlines

Pacific Southwest Airlines (PSA) is a major U.S. airline headquartered in San Diego, California. It is the largest California-based airline in the United States. PSA calls itself "The World's Friendliest Airline" and paints a smile on the nose of its airplanes, the PSA Grinningbirds. Opinion L.A. of the Los Angeles Times called PSA "practically the unofficial flag carrier airline of California".

The airline initially operated as an intrastate airline wholly within the state of California before expanding to other destinations in other western states in the U.S. following the Airline Deregulation Act of 1978 and also eventually started operating international service to several destinations in Mexico.