The Helicopter Association International (HAI) has released a document, Understanding GPS Interference Events, to explain the practice of purposefully jamming and/or testing of GPS signals, as well as where members can go to get information on Notams associated with the GPS interference exercises. The Department of Defense is required to conduct the exercises, HAI noted, adding that they involve intentionally degrading or outright denial of the GPS signal.
The National Telecommunications & Information Administration’s Office of Spectrum Management evaluates the event to determine the contours of where interference could be experienced, creating a “bug splat” plot to depict interference exposure levels for certified aviation GPS. The FAA uses those contours to graphically depict affected areas in Notams. A subset of these Notams are published on the FAA’s Safety Team (FAASTeam) website and emailed to subscribers of the Safety Program Airmen Notification System. Other information sources listed by HAI include the Wide Area Augmentation System (WAAS) Test Team website, the FAA WAAS website, and the Coast Guard Navigation Center website.
HAI discussed the interference practice and provided the resources as the FAA issued its latest flight advisory of GPS interference testing, which began yesterday and will continue through January 22 at the National Training Center near Barstow, California.