United Airlines says it will return to Africa this winter, when it will become the only airline to fly non-stop between the United States and Cape Town, South Africa.

Starting Dec. 15, United will fly a Boeing 787-9 between its Newark hub and Cape Town, the second largest city in South Africa with a metropolitan area population of nearly 4 million and a location on the southern tip of the African continent.

The route serves “a huge business market in South Africa and a high premium leisure market,” said Patrick Quayle, United vice president of international network.

United had thought it would become the first airline ever to fly non-stop between Cape Town and the United States. However, South African Airways flew Cape Town-Miami as recently as 1999

Cape Town is the largest city in Africa that lacks non-stop service from North America, Quayle said. Each day, about 350 people fly each way between the two destinations, utilizing routes with one or more stops.

The next two cities on the list are Entebbe, Uganda, with 140 daily passengers each way and Abuja, Nigeria, with 130 daily passengers each way.

Currently, all service from the United States to South Africa has Johannesburg as the destination, with flights from New York Kennedy and Washington Dulles (direct, one-stop) on South African Airways and daily service from Atlanta on Delta. South African is United’s partner in the Star Alliance.

Johannesburg, a difficult market for airlines to serve because of its high altitude (5,751 feet) and warm climate, makes nonstop trans-Atlantic flights difficult for the 787. Other carriers use a 777LR or four-engine aircraft for higher thrust on takeoff.

United’s Boeing 787-900 seats 252 passengers in three classes including premium economy. The eastbound flight takes 14 ½ hours while eastbound takes 15 hours and 50 minutes. The flight cover 7,817 miles.

The service will initially be seasonal. However, the airline is open to extending the schedule if the demand builds. The carrier started San Francisco-Tahiti as a thrice-weekly, winter flight and now flies the route year-round.

In its previous effort to serve Africa, United flew Houston to Lagos, Nigeria. The flight operated between 2011 and June 2016.

In May 2016, United said it would end the service the following month. “The IAH-LOS route has been underperforming financially for several years,” United said in a memo to employees. “Because of its importance to key Houston-based customers, we continued to invest in it; however, the recent downturn in the energy sector has caused these customers to spend less on travel.”

In the past two years, United has started 22 international destinations including Newark to Naples and Porto; Washington Dulles to Tel Aviv starting May 22, and San Francisco- Tahiti. “We are constantly look for ways to grow and add unique content,” Quayle said.