United Airlines plans to grow its hub at Denver International airport to 400 daily departures in 2019, potentially pushing it ahead of other hubs to become the second busiest in its system.

The “proposed” growth in departures comes on the continued strong performance of the Denver hub, says captain Rob Biddle, United’s chief pilot for Denver, in a letter to pilots on 10 November.

“At that level we will surpass both [Houston Intercontinental’s] and [Newark’s] current daily totals respectively,” he says.

United is scheduled to operate an average of 363 daily departures from Denver in December, FlightGlobal schedules show. By comparison, it operates 521 from Chicago O’Hare – its largest hub – 484 from Houston Intercontinental and 377 from Newark.

The Chicago-based carrier has grown in Denver since 2013. While its departures from the airport are down about 1% over the period, seat capacity is up more than 20%, schedules show.

“I have lots of plans putting even more airplanes through [Denver] in the future,” United president Scott Kirby told employees in January. These followed previous comments where he called Denver the airline’s “most profitable” hub.

United added new service to Columbia (Missouri), Pueblo and San Luis Obispo from Denver in 2017, schedules show. Seat capacity was up 5.3% year-over-year on less than 1% fewer departures.

In 2018, the Star Alliance carrier and its regional partners have already announced flights to eight new destinations from Denver, including London Heathrow, Moab (Utah) and Paine Field near Seattle.

Analysts expect United to grow capacity at an accelerated rate in 2018, with JP Morgan forecasting a roughly 4.3% systemwide increase. This will follow a roughly 3.5% increase this year.

The growth in Denver comes as the airport prepares to add 11 gates to concourse B for United. Six gates will be built on the western end and a new regional jet wing on the northeastern corner of the concourse, airport documents show.

The new gates, as well as new checked bag system, will open in 2020, says Biddle.

The additional facilities for United are part of a larger $ 1.5 billion expansion that will see Denver add 39 gates across the airport’s three concourses by 2023.

The mainline carrier is already the largest in Denver with a 42.2% share of passenger traffic year-to-date in August, airport data shows. Southwest Airlines is the second largest with a 29.4% share and Frontier Airlines third with an 11.7% share.

United was not immediately available for comment on the growth.

Updated with analyst capacity growth forecast