AOPA/NBAA: Address Military GPS Jamming

There’s no question the global positioning system, GPS, has revolutionized the way everyone on the planet navigates. In little more than 25 years, the technology has become ubiquitous in automobiles, cellular phones and cameras, to name only a few devices. Oh, and aircraft surveillance/navigation systems, too, which may be its most critical application. None of this would have happened if its reliability and accuracy weren’t so much better than the electronic navigation systems that came before.

Perhaps because of its reliability and accuracy, the U.S. military has for years conducted research into how GPS may be jammed and how jamming can be countered. That testing is conducted at various locations, including offshore, and presumably can affect GPS signal availability and quality throughout the U.S. Of course, any jamming of GPS for whatever purpose is designed to disrupt its availability to all users, including airborne aircraft. The military’s jamming research has and likely will continue to impact civilian users, including aircraft operators. That’s important because not only is GPS increasingly the sole aviation navigation system in many areas, it’s also a core technology of ADS-B, the FAA’s surveillance system.

We don’t know about you, but it seems every time we get a preflight briefing, there’s at least one Notam about GPS jamming. As the image below from a recent FAA FAASTeam notice depicts, U.S. military jamming tests can affect GPS’s availability over a widespread area, According to a February 2, 2021, article on Engineering.com, “There have been 90 reports of cases of GPS jamming filed on NASA’s Aviation Safety Reporting System (ASRS) over the past eight years—most occurring between 2019 and 2020—detailing abrupt signal disruptions….” According to Engineering.com, “Overall, approximately 173 incidents occurred over six months in 2017, with 60 more arising in early 2018…. The areas most affected by GPS interference are Southern California, southern Nevada, southwestern Utah, western Arizona, and parts of the Pacific Ocean.” The article notes this isn’t a new problem, since the military admitted at least as far back as 2013 that it was aware of the potential for GPS service interruptions.

Recognizing all this, the non-profit research organization Radio Technical Commission for Aeronautics (RTCA) recommended to the FAA in March 2018 some 25 steps the agency and the U.S. Department of Defense could take to minimize the impact of related testing on civil aviation. To date, however, little has come from those recommendations. And the Aircraft Owners and Pilots Association (AOPA) and the National Business Aviation Association (NBAA) want to know why there’s been no progress over the intervening three years. In February 2021, the two associations wrote the FAA and the Department of Defense to put some pressure on them to follow through on the recommendations and request a thorough briefing and update on their status.

“Despite reduced operations in the NAS over the past year, General Aviation continues to show increased activity and volume, exceeding commercial airline operations. In recent months, operators have continued to report operational impacts and reduced access to airspace and airports resulting from intentional GPS jamming events,” the letter noted. “While the RTCA report provided many suggested mitigations and recommendations about protocol to reduce the operational impact on civilian operations, the industry has yet to receive any feedback from the agencies on the disposition of those proposed mitigations. Therefore, NBAA and AOPA are seeking a detailed briefing and update on the status of that industry report, including the work done over the past several years to help provide operational relief,” the two groups wrote.

The National Airspace System “has become increasingly reliant on GPS as the primary source of navigation and aircraft system functionality while reducing the ground based navigational backup infrastructure,” AOPA/NBAA said.