Today, most of us would probably rate cellphones, ATMs and the Internet as the three most useful modern gadgets we use regularly. We likely wouldn’t rank GPS up there, and maybe not even in the top 10. Yet without GPS, those three wouldn’t work too well, if at all, and neither would a host of other things that we depend on (reliable electrical power; banking systems; national and worldwide telecommunications, including air traffic control; and car navigation, to name a few). And with NextGen slowly approaching, aviation’s dependence on GPS will grow exponentially.
But their dependability is not assured for the future. Considering their importance, the GPS satellite signals are improbably weak: someone compared them to detecting a Christmas tree light bulb in New York, when viewed from Los Angeles. The reason is that in the 1970s USAF developers had classified technology that could hide them from adversary detection deep in the atmospheric “noise.” But parallel civil technology eventually caught up and public GPS access was granted in 1983. On Sept. 10, 2001, the Department of Transportation warned that the weakness of the signals made them vulnerable to deliberate jamming. Events the very next day demonstrated the reality of ill intent.
