Mobile network to undergo GPS interference tests

Impact on GPS signals to be studied in Nevada

May 12, 2011

With tests starting soon to determine whether a mobile network's expanded use of bandwidth would pose a threat to GPS signals, AOPA is urging any pilots who experience problems with GPS reception near the test sites to notify the FAA and the association promptly of the impact on their flights.

The FAA has issued two flight advisories in connection with the testing of LightSquared's mobile broadband network near Las Vegas and Boulder City, Nev., May 16 through 27. The tests, ordered by the Federal Communications Commission as a condition of LightSquared's waiver to expand, could result in unreliable or unavailable GPS signals, the advisories said.

Results of the tests will be scrutinized carefully by a coalition of GPS users across many industries and their growing ranks of supporters in the federal government. The coalition members have expressed their concerns to the FCC about the possible threat to GPS, which is relied upon ever more for uses ranging from the Next Generation air transportation system to emergency rescue services. AOPA reported March 9 on the formation of the Coalition to Save Our GPS, which brought together GPS users across industries to assure that regulators protect signal quality from interference by other bandwidth users. The company's proposed expansion would include the installation of thousands of ground stations for its high-powered mobile network.

In a white paper, the coalition criticized the FCC's nonstandard approval decision in the case of LightSquared—pointing out that the usual FCC process is to “conduct extensive testing followed by approvals. For LightSquared, the process was approve first, then test.”

After AOPA and other organizations objected, the FCC imposed several other compliance conditions. The coalition also insisted on safeguards including that the FCC require that concerns be resolved to the satisfaction of existing GPS providers and users, and that GPS users not bear additional costs to prevent interference.

The importance of the tests to the outcome of the LightSquared regulatory review makes it critical that any signal degradation experienced by pilots be reported to the FAA through air traffic control or flight service. Pilots also should forward their findings to AOPA.

Notices to airmen will be published at least 24 hours in advance of any GPS tests. Pilots are advised to check notams frequently for possible changes prior to operations in the area.

Dan Namowitz

Dan Namowitz | Aviation Writer

Dan Namowitz is an aviation writer and flight instructor. He has been a pilot since 1985 and an instructor since 1990.