Southwest Airlines, the largest carrier at Long Island MacArthur Airport, said Tuesday that beginning in January it plans to cut 190 daily flights, including one of six daily trips between the Ronkonkoma airport and Orlando, Fla.

The Dallas-based airline, one of the most successful discount carriers in the country, has so far resisted cuts resulting from higher fuel costs that other airlines have had to make in the past year or so.

Whitney Eichinger, a Southwest spokeswoman, said that all of the flight reductions will begin Jan. 11 throughout the airline’s route system. The 190 flights represent nearly 6 percent of Southwest’s daily schedule of about 3,400 flights.

Eichinger said that the flight reductions are the result of an overall decline in air travel between January and early March. She said some of the flights could be restored in the spring.

“We’re just looking to trim those flights that don’t have heavy demand even in busy times,” Eichinger said.

Southwest has six daily nonstop flights between Long Island MacArthur and Orlando. It will be down to five after Jan. 11.

Previously, Southwest said it might not add any new flights in 2009. The airline has slowed its growth this year because of soaring fuel prices and the slowing economy, which has cut into leisure travel.

Southwest is the only major airline to have posted a profit in the first half of this year. The airline has been able to avoid the problems experienced by most others because of a fuel purchase program that has allowed it to lock in lower prices.

Southwest is one of a number of carriers that will be cutting flights this year. American Airlines, the nation’s largest, is reducing about 8 percent of its flights after Labor Day. United Airlines anticipates cuts of about 16 percent.

Ray Neidl, who follows the airline industry for Calyon Securities, an investment banking firm, said in a report that major carriers could lose $6.5 billion this year. Neidl said fuel costs have risen faster than expected.