A few years back the government took it upon themselves to build a very nice airport on the island, La Paloma Airport. There is only one airline La Costeña Airlines, along with some private aircraft, which fly to Ometepe Island. Flights are limited to Sunday and Thursday's right now and you can expect to pay US$57.50/per person for a one way ticket. Here is a schedule of the available flights to the island:
NOTE: It is actually one small 12-seater plane that begins and ends in Managua yet hops through three other locations and back, on its twice-a-week journey. The times listed below are the current departure times from each location. And it is the same schedule, and flight numbers, on every Sunday and Thursday.