How does satellite communication (SATCOM) work for aviation?

Aviation SATCOM provides communication beyond VHF range, especially over oceans. Systems include: Inmarsat - geostationary satellites covering most latitudes, Classic Aero (voice, low-rate data) and SwiftBroadband (IP data); Iridium - LEO constellation with global coverage including poles, voice and ACARS data; and Future LEO constellations for high-speed connectivity. SATCOM enables: ATC voice and data communication (CPDLC), Airline operational data (AOC), Passenger connectivity, and Real-time flight tracking. Datalink modes include ACARS, ATN, and IP. SATCOM antennas range from low-gain patches to high-gain steerable arrays. Cost per minute/kb drives operational usage decisions.