The FAA’s Alaska Region this year will assess the suitability of a communications satellite system with an unusual history to supplement its Capstone automatic dependent surveillance-broadcast (ADS-B) project. Called Iridium, and employing 66 satellites orbiting the earth, the system’s operating company in 2000 faced bankruptcy, and only an 11th-hour intervention and buyout prevented all 66 space vehicles being deliberately destroyed by fiery reentries into the earth’s atmosphere so as to not worsen the company’s operating losses. Following acquisition of the system, Iridium’s new owners obtained significant contracts with the Department of Defense and other customers, and its future now seems secure.
But why does Capstone even need a supplementary satellite system? In ADS-B, widely dispersed ground-based transceiver (GBT) stations are key elements, receiving transmissions from equipped aircraft and retransmitting them to distant ARTCCs, and also receiving information from the ARTCCs and then rebroadcasting it to aircraft in their local areas. But flying down a valley in Alaska, or being behind an intervening mountain range, can block ADS-B’s UHF transmissions to and from the GBTs, effectively negating the system’s safety benefits.
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