Sun Country Airlines on Tuesday announced routes to and from Nashville, including nonstop service to Minneapolis-St. Paul International Airport, as the carrier continues adding new markets.

The Eagan-based airline will operate winter seasonal service between Nashville and New Orleans, Miami, Tampa, Orlando and Fort Myers, Fla. Like most of its seasonal routes, Sun Country will fly each offering a couple of days each week. The MSP-to-Nashville International Airport flight will operate on Thursdays and Sundays.

"Nashville is a popular destination for travelers in the Twin Cities, and we are excited to offer them an affordable, nonstop option," Jude Bricker, chief executive of Sun Country, said in a statement.

Sun Country's business model is in the midst of a major shift toward low-cost, leisure travel. That is spurring changes that range from the design of aircraft interiors to the addition of new fees.

The transition is seen by some as critical to the airline's financial survival, but the process has created some customer frustration. Sun Country experienced a hiccup recently when a contractor it hired to handle some ground activities at MSP couldn't hire staff quickly. It withdrew the deal and again took control of that work, at least for awhile.

"The new service in Nashville is part of our continued effort to grow as a brand, which will allow us to invest in our employees and community here in Minnesota, " Bricker said.

Bricker, who was appointed the airline's CEO in July 2017, is moving Sun Country away from being an "in-betweener" airline, wedged between the traditional legacy carriers and the ultra-low-cost carrier (ULCC) options like Spirit Airlines. Sun Country is leaning toward the ULCC model by emphasizing airfare value in an attempt to appeal to families and budget travelers.

This tactic aligns with other ULCCs, a new air-traffic trend report from Boyd Group International, an aviation forecasting and consultancy firm, found.

Rather than meeting existing travel demand like the major airlines, such as Delta Air Lines or United Airlines, the ULCC model tries to create new demand by treating its service as a discretionary consumer expense, essentially creating a new pool of air travelers who otherwise wouldn't fly that route.

"There is no set of metrics to determine target airports that are viable for ULCC entry. These are entirely subjective corporate decisions," the Boyd report found.

A key strategy of Bricker's leadership team is expansion outside MSP, where most of its customers have historically originated. Sun Country recently added new seasonal routes in St. Louis, Madison, Wis., Dallas-Fort Worth and Portland, Ore.

Including the Nashville additions, Sun Country offers 70 nonstop routes.