A corrupted upgrade to a large class of receivers was to blame for what was initially suspected to be a degradation of GPS service across much of the United States (see FAA graphic).

Work by the FAA and industry groups revealed that many Rockwell Collins receivers had received a bad update. See: AIN Online “Collins GPS Receivers Suffer Reception Outage.”

GPS signals can and have been degraded and blocked by a wide variety of causes including solar activity, government operations, criminal activity and accident. In a safety of life application such as aviation, it is understandable that authorities would want to get warnings out as quickly as possible, even while they were still diagnosing the problem.

Previous outages and widespread degradation of satellite navigation signals have included:

It is possible for degraded GPS signals to cause some equipment and applications to fail, while not impacting others at all. In January 2016, for example, many navigation receivers were unaffected. The greatest impacts felt by GPS timing users. The terrestrial ADS-B network was one of many systems degraded during that period because of timing.