United Airlines will begin flying a Boeing 757-300 to Ronald Reagan Washington National airport in March, adding capacity at the slot-restricted airport.

The Chicago-based Star Alliance carrier will operate the 213-seat aircraft daily from Washington National to its Denver hub on 3 March and to its San Francisco hub on 23 March, a spokesman confirms.

United replaces an Airbus A320 with 150 seats and a Boeing 737-800 with 166 seats on the Denver route and a 737-800 on the San Francisco route, Innovata schedules show. This represents an at least 28.3% increase in seats per flight on both routes.

The airline only has one exemption to Washington National’s 2,012km perimeter for Denver and one for San Francisco, barring it from adding frequency on either route and likely driving the decision to operate larger aircraft.

“We are shifting capacity away from Houston and into other growing markets, like Denver and San Francisco,” said Jim Compton, chief revenue officer of United, on its 2016 capacity plans in January. This growth would likely include new routes and capacity to the US east coast, he added.

Flying the 757-300 to Washington National will give United the title of operating the largest regularly scheduled aircraft at the airport.

While National can handle larger aircraft, for example Boeing flew a 787-9 to the airport for a Vietnam Airlines delivery in July 2015, airlines do not operate widebody aircraft there on a regularly scheduled basis.

The 757-200 is the largest aircraft operating regularly scheduled flights to National currently, Innovata data shows. American Airlines operates the type to Phoenix and Delta Air Lines to Atlanta and Salt Lake City.

"We’ll work with United to support its operations, as we do with all airlines that serve the airport," says a spokeswoman for Washington National operator the Metropolitan Washington Airports Authority (MWAA). "Upgauging isn't new at Reagan National, we’ve seen a number of airlines do it in recent years, contributing to record passenger numbers, a strain on airport facilities and added congestion for passengers."

Passenger traffic at Washington National increased 11.4% to 21.2 million, surpassing its larger sibling Washington Dulles International airport, through November 2015, airport data shows.

MWAA plans more than $1 billion in capital improvements to the airport, including connecting three of National's four concourses behind security and building a new 14-gate regional concourse, by 2020.

Source: Cirium Dashboard