Allegiant Air, Long Island MacArthur Airport's newest airline addition, which joined the financially strapped Ronkonkoma airport in December, has announced it will suspend service during the summer and fall months.

The Las Vegas-based low-cost airline will stop flying out of the airport on May 26 and anticipates returning in December, according to a company news release. Customers who purchased tickets for those months will be contacted by the company for a full refund, the release said.

MacArthur Airport, owned by Islip Town, has about 8,000 departing flights a year. It lost 46 percent of its daily flights between 2007 and 2012 and has suffered nearly $4.2 million in losses in the past three years. It was recently projected to be down another $1.4 million in 2013, threatening the financial health of the town, which has its own fiscal issues as it continues to battle a deficit of $11.3 million.

The town's liaison to the airport, Councilman John C. Cochrane Jr., said Allegiant was initially "putting their foot in there and seeing if they liked the service market" out of MacArthur.

"Because they limited us to Punta Gorda, they really limited us in terms of expansion," he said of the Florida airport destination.

The numbers of passengers using MacArthur have also fallen. In 2012, the airport saw just under 679,000 passengers, compared with 1.2 million boarding planes in 2007. Airport staff and overtime have been cut in recent years, among other cost-saving measures, and a general aviation landing fee was implemented, all to help keep the airport afloat.

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Eric Fletcher, Allegiant Travel Co.'s manager of airports, apologized "to any travelers who are inconvenienced by this decision."

"We are always disappointed to cancel flights. However, we pride ourselves on our flexibility and receptiveness to market demand, and during the busy summer travel season, we have a responsibility to use our resources where they are most beneficial to our overall success," Fletcher said in a statement.

The airline had been running two weekly direct flights to and from the Sunshine State, but with the weather here warming, Long Islanders no longer need to fly south for warm weather and beaches, Cochrane said. "If they come back in the fall, we'll welcome them back," he said.

There were no Allegiant customers at MacArthur Wednesday afternoon, as the airline only flies on Fridays and Mondays. But many were concerned about the airport's future.

"They have the space. It's a shame they can't get more airlines here," said Theresa Zummo, a Shirley resident who was returning from Orlando on a Southwest Airlines flight.

Two other airlines operate at the airport: PenAir and US Airways Express.

Islip is hopeful that American Airlines gets federal approval for two direct daily flights from MacArthur to Reagan National Airport in Washington, D.C.