San Diego International Airport

San Diego International Airport is the busiest single-runway commercial airport in the United States and one of the busiest single-runway airports in the world, serving 39 airlines on 234 routes to 113 nonstop destinations from one 9,401 ft (2,865 m) east-west strip. Also known by the historic name Lindbergh Field — in honor of Charles Lindbergh, whose Spirit of St. Louis was built in San Diego and first flown from the site in 1927 — SAN sits 5 km (3 mi) northwest of downtown San Diego at just 17 ft (5 m) of elevation on the eastern shore of San Diego Bay. The airport's defining operational challenge is the Parkway Approach: pilots landing on Runway 27 must clear the Centre City Tower, the Banker's Hill neighborhood, and Balboa Park before executing a steep 3.5-degree descent — nearly 20 percent steeper than the ICAO-standard 3.0-degree glideslope — with the threshold positioned less than 3 km (1.9 mi) from the skyscrapers of downtown. The approach is one of the most visually dramatic at any major US airport and one of only a handful of Category B airports (requiring special pilot training) in the country. Runway capacity is the airport's fundamental ceiling: despite handling over 24 million passengers per year, SAN cannot add a parallel runway due to the constrained peninsula geography between the bay, Interstate 5, and the city. SAN operates as a focus city for Southwest Airlines — the largest carrier at the airport — alongside a strong presence from Alaska Airlines (successor to the Virgin America operation), American, Delta, and United. International service is modest in airline count but geographically distinctive, reaching London, Frankfurt, Tokyo, Vancouver, and several Mexican destinations. A new Terminal 1 replacement, opened in phases from 2023, introduced 19 new gates and a consolidated rental car and ground-transport complex.