Five Major Airports Operate on One Runway

Five major airports worldwide handle tens of millions of passengers each year using only one active runway. Any closure of that runway for maintenance, weather, or an incident halts all operations at these critical hubs. The airports include the busiest single-runway facilities in the United States, China, mainland Europe, and the United Kingdom. The five airports on this list handle between 25 million and 45 million passengers annually on a single active runway. They include the busiest single-runway airports in the United States, Europe, and the world. Some have second runways under construction or approved. Others have replacement airports planned for the next decade.

San Diego International Airport (SAN)

25.2 million passengers per year

San Diego International Airport (SAN) is the busiest single-runway commercial airport in the United States. It served a record 25.24 million passengers in 2024 using its single 9,401-foot runway. The airport is located just three miles northwest of downtown San Diego, hemmed in by San Diego Bay, a Marine Corps base, a major interstate, and residential neighborhoods. There is no physical space to add a second runway, a constraint that has blocked proposals since the 1960s.

Southwest Airlines holds the largest market share at SAN, carrying nearly a third of all passengers. Alaska Airlines operates a hub there. The new Terminal 1 opened its first phase in late 2025, adding 19 gates. A second phase will add 11 more gates by 2028. This terminal investment addresses passenger capacity but does not change the fundamental runway limitation. A closure would shut down commercial aviation for the entire San Diego metropolitan area, home to 3.3 million people. The nearest alternatives, Tijuana's airport and John Wayne Airport in Orange County, cannot absorb San Diego's traffic volume.

Xiamen Gaoqi International Airport (XMN)

29.2 million passengers per year

Xiamen Gaoqi International Airport (XMN) is the busiest single-runway airport in China. It handled 29.19 million passengers in 2025 on a single 11,155-foot runway. The airport is located on the northeastern tip of Xiamen Island, making expansion impossible due to water and urban development. It serves as the main hub for XiamenAir and a focus city for several other Chinese carriers.

Unlike other airports on the list, Xiamen Gaoqi has a definitive end date. The airport will close entirely in late 2026 when the new Xiamen Xiang'an International Airport opens on Dadeng Island. The replacement airport will have two parallel runways in its first phase, with capacity for 45 million passengers annually.

Lisbon Humberto Delgado Airport (LIS)

Lisbon Humberto Delgado Airport (LIS) is Portugal's primary international gateway and the busiest single-runway airport in mainland Europe. It handled 35.1 million passengers in 2024 on a single 12,484-foot runway, exceeding its designed capacity. The airport is a major hub for TAP Air Portugal and a base for Ryanair and easyJet.

There is no second airport serving the Lisbon metropolitan area. A runway closure would halt all operations at the facility handling the majority of Portugal's international air traffic. Portugal has been planning a replacement airport for decades. The current proposal, named Luís de Camões Airport, is targeted to open between 2035 and 2037. Until then, the airport operator is investing approximately €400 million in interim upgrades to increase throughput.

London Stansted Airport (STN)

London Stansted Airport (STN) handled a record 30 million passengers in 2025 on its single 10,000-foot runway. It is Ryanair's largest base in the world, connecting over 150 destinations. The airport is located 42 miles northeast of central London.

In December 2025, local authorities approved raising Stansted's annual passenger cap from 43 million to 51 million over the next 20 years. The airport's owner stated this increase would be achieved using larger aircraft, not by building a second runway. A proposal for a second runway was withdrawn in 2010 and no plans exist today. A closure would uniquely disrupt Ryanair's network, as many of its Stansted routes have no alternative London departure point with the same carrier.

London Gatwick Airport (LGW)

London Gatwick Airport (LGW) is the busiest single-runway airport in Europe. It handles over 45 million passengers per year on its main runway, which measures 10,879 feet. The airport also has a standby runway, but it is too close to the main runway to be used independently for simultaneous operations.

Gatwick's standby runway can only be used when the main runway is closed, providing no redundancy for simultaneous operations. The report notes that any closure of the main runway at these five airports brings an entire region's air traffic to a standstill with no operational fallback.