WASHINGTON ― A bipartisan group of 32 senators sent the Federal Communications Commission a letter urging it to reverse course on its decision to allow Ligado to deploy a nationwide mobile broadband network, saying it may disrupt GPS signals.

Though the letter is led by Senate Armed Services Chairman Jim Inhofe, R-Okla., and ranking member Sen. Jack Reed, D-R.I., who have repeatedly criticized the decision for endangering the military’s ability to navigate, the new letter emphasized the potential impact on an array of commercial activities and showed an expanse of support on Capitol Hill. Defense News obtained a draft of the letter, which the FCC was sent on May 15.

Ligado has argued its use of the electromagnetic spectrum’s L-Band will further fifth-generation wireless networking and that it would take steps to reduce potential interference with GPS. But the letter demonstrates the opposition beyond the military’s traditional allies, just as Inhofe is weighing congressional action against the decision.

Because the FCC falls under the Commerce, Science and Transportation Committee, it’s notable that six senators on both Commerce and SASC―Sens. Deb Fischer, R-Neb.; Dan Sullivan; R-Alaska, and Rick Scott, R-Fla.; Gary Peters, D-Mich.; Tammy Duckworth, D-Ill., and Krysten Sinema, D-Ariz.―joined the letter.

Its co-signers include Senate leaders like Commerce’s top Democrat, Sen. Maria Cantwell, D-Wash.; Agriculture, Nutrition, and Forestry Chairman Pat Roberts, R-Kan.; Finance Chairman Chuck Grassley, R-Iowa; Energy and Natural Resources Chairman Lisa Murkowski, R-Alaska.; Budget Committee Chairman Mike Enzi, R-Wyo., as well as Republican Conference Chairman John Barrasso, R-Wyo., and Vice Chair Joni Ernst, R-Iowa.

The letter echoes a familiar argument among opponents, that the FCC’s April 20 order to permit Ligado’s application to deploy a terrestrial nationwide network to provide 5G services may not protect adjacent-band operations related to GPS and satellite communications from harmful interference. The letter emphasizes that this would “impact countless commercial and military activities.”

“American families rely on its free precise timing and navigation for thousands of functions every day, including banking, logistics, agriculture, weather, and travel. The aviation community uses GPS and satellite communications for navigation, terrain and obstacle avoidance, and aircraft tracking necessary to safely operate commercial, business, military, and emergency response aviation activities, including medevac and aerial firefighting,” the letter reads.

“The agriculture industry uses GPS to facilitate precision-based practices that have facilitated dramatic improvements in productivity. The trucking and logistics industries rely on GPS for route planning and tracking of shipments and equipment to safely and efficiently move freight throughout the country. FCC’s actions also threaten weather satellites, crucial to saving lives and property when tornadoes, hurricanes and floods strike. GPS also forms the backbone of countless military operations and applications.”

While DoD and its allies have argued that Ligado’s plan for the L-Band would create interference with GPS capabilities, Ligado’s side argues DoD’s testing does not accurately capture the mitigation plan the company has developed over the years and that there is no true proof that interference will be an issue. Trade groups last week called for the National Academy of Sciences to step in as a neutral arbiter and perform new tests.

The Senate letter called the FCC’s decision, “hurried,” and said the FCC had created “an unclear and ill-defined standard based on a limited set of tests”―and that it would do better to craft a comprehensive “data driven performance based standard for what constitutes harmful interference.” The FCC, it said, “did not provide a technical forum to resolve the significant disconnects [associated with] Ligado’s privately funded testing.”

The Senate letter comes after a bipartisan group of 22 House Armed Services Committee members sent their own letter last week urging the FCC to reverse itself. The Senate Armed Services Committee held a hearing May 6 on the topic where current and former military officials presented a range of arguments.

In a floor speech May 12, Inhofe blasted the FCC decision and cast the issue as a battle between “airlines, pilots, farmers, truckers, marine manufacturers, conservationists, equipment manufacturers and distributors, road builders, weather forecasters, and GPS device makers” who opposed to the decision―against Ligado’s lobbyists and hedge fund investors.

“Reliable GPS and satellite communications is important to everyone in America and drives much of our nation’s economy,” he said. “We should not sacrifice GPS reliability for the sake of lobbyists and hedge fund investors on Wall Street.”

Other members to sign the letter included Michael Bennet, D-Colo.; John Boozman, R-Ark.; Bill Cassidy, R-La.; Susan Collins, R-Maine; Kevin Cramer, R-N.D.; Mazie Hirono, D-Hawaii; John Hoeven, N.D.; Cindy Hyde-Smith, R-Miss.; Doug Jones, D-Ala.; Angus King, I-Maine; Joe Manchin, D-W.Va.; Martha McSally, R-Ariz.; David Perdue, R-Ga.; Rob Portman, R-Ohio; Mike Rounds, R-S.D.; Jeanne Shaheen, D-N.H., and Sheldon Whitehouse, D-R.I.

Update: This report was updated after the letter was sent and to include the signatures of Sens. Maria Cantwell and Bill Cassidy.

Aaron Mehta contributed to this report.

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

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