Long Island’s complicated development picture has many puzzling pieces, but few more vexing than Long Island MacArthur Airport.

Nearly everyone agrees it’s an asset to the region. It’s well-situated, in Ronkonkoma, off the Long Island Expressway. It could be a huge economic driver, a convenience to travelers and an essential part of the Island’s 21st-century transportation network.

And yet it’s been grounded for years. Flights, passengers and revenues peaked nearly a decade ago. A slide that long can harden skepticism about a revival.

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So count us a little startled but cautiously excited to say that a turnabout seems to be on the horizon. Important decisions still must be made. The dominoes of progress are fragile. But enough good things are happening that it’s not unreasonable to think that MacArthur finally is poised to fulfill its potential.

The primary piece of evidence is the U.S. Customs facility to be built at the airport, now that Gov. Andrew M. Cuomo has announced that the state will provide the final $6 million needed for the $11 million project. It’s a game-changer.

Such a facility will allow international flights at MacArthur. That will create a need for more connecting flights to other parts of the country. And that means more jobs, more visitors spending their money here, and more destinations and easier travel for many Long Islanders.

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Cuomo wants to get it done now. His office has summoned representatives from the airport and Islip Town, which owns and operates MacArthur, to Albany for a meeting this week.

The timing is propitious. Air travelers using MacArthur will enjoy faster trips intra-Island, and to and from New York City, when the second Long Island Rail Road track being built between Farmingdale and the Ronkonkoma Hub is finished. That would position MacArthur to help alleviate chronic congestion at LaGuardia Airport, and take advantage of its lengthy upcoming renovation.

MacArthur, too, needs an upgrade. One of its two runways is too short for international jets. Lengthening it would allow more efficient operations and provide redundancy and safety in bad weather. The longer runway is in the airport’s new master plan expected to receive Federal Aviation Administration approval this spring. Sen. Chuck Schumer and Rep. Lee Zeldin, both staunch champions of MacArthur, have vowed to get FAA money for the extension. Schumer has used FAA funding formulas for runway projects in other parts of the state.

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Islip Supervisor Angie Carpenter, who has made reviving the airport a priority since taking office last year, says her negotiations with several domestic and international carriers about servicing MacArthur might soon bear fruit.

She recently visited the Dallas headquarters of Southwest Airlines, the airport’s principal tenant, to begin to repair their rocky relationship and lay the groundwork for expansion. She and chief executive Gary Kelly exchanged gifts. Carpenter left with a Southwest lapel pin, and Kelly has one of Carpenter’s toy truck marketing prototypes, whose side panels tout easy access to Southwest’s flights from MacArthur.

And with airport commissioner Robert Schaefer retiring, she’ll be able to pick her own person, which should lead to better communication.

One issue to be worked out is how to hook up the airport to sewers. Besides helping tenants and jump-starting development, sewers also would make it cheaper to get rid of waste, significantly reducing operating costs for Southwest and any airline thinking of coming to MacArthur.

Photos of the baggage pickup area of Long Island MacArthur Airport in Islip on the afternoon of April 29, 2015. Newsday / Thomas A. Ferrara Photo Credit: Newsday / Thomas A. Ferrara

Right now, sewers from the massive Ronkonkoma Hub redevelopment are planned to go through the Village of Islandia, bypassing the airport. An alternative route also hooking up MacArthur and its surroundings would cost more and take longer to build. That would threaten the viability of the Hub project, which should break ground this year. Town and Suffolk County officials must keep the Hub on track while also getting the airport on sewers. Extra costs could be covered by one of the two pots of state transformation funding announced by Cuomo last year.

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In the meantime, change will come quickly to MacArthur. Islip expects to build a temporary customs facility to process passengers in six months, and a permanent one in two years. Suffolk Executive Steve Bellone included $500,000 in marketing money in the county budget to tell the world about it.

None of this means MacArthur suddenly will be flush with flights and fliers. It doesn’t guarantee an end to the death spiral of new airlines wanting to see more passengers, while passengers wait for more flights. Some companies will need to make a leap of faith.

But the state, town and airport are building a bridge. The leap won’t be blind. Airlines will have more reason to offer more routes. Customers, including Long Islanders, will need to follow.

In the end, it will be up to them whether MacArthur’s revival can take us where we want to go.