In some areas, flying may be the only practical way to get around.
State-operated Garuda (http://www.garuda-indonesia.com) handles international flights (though you might also use them for transport within Indonesia), while Merpati is the domestic operator.
Provincial services are supplemented by numerous airlines, including Mandala, Lion Air, and Batavia Air, among others. It’s essential to reconfirm your seat, as waiting lists can be long and being bumped off is a regular occurrence; get a computer printout of the reconfirmation if possible. Arrive at the airport early, as seats on overbooked flights are allocated on a first-come, first-served basis.
At other times, “fully booked” planes can be almost empty, so if you really have to get somewhere it’s always worth going to the airport to check.
Fares depend on the airline, ticket type, and travel date, but are typically good value considering the mileage covered and time saved. A flight between Bali and Jakarta, for example, will cost around Rp500,000; between Bali and Flores will cost around Rp700,000.