Ligado 5G Approval and GPS Interference: What Boaters Should Know

In late June, BoatU.S. issued an alert advising boaters who rely on GPS to prepare for possible signal disruption and, potentially, the need to replace GPS-based equipment. The warning followed a controversial Federal Communications Commission (FCC) decision made in April that cleared the mobile satellite services operator Ligado Networks to deploy a 5G network on frequencies that critics warn could interfere with GPS reception.

The dispute over Ligado’s plan goes back more than a decade, to the LightSquared era. In 2011 the FCC granted LightSquared a conditional waiver to deploy a terrestrial network using spectrum adjacent to GPS frequencies. Strong opposition from the GPS industry and the U.S. Air Force followed, arguing the plan could overwhelm the weak satellite signals that GPS receivers depend on. The FCC later suspended that waiver in 2012, and the company entered bankruptcy. It reemerged as Ligado in 2016 with a revised plan, and the FCC’s recent approval allows the company to transmit in portions of the L-band spectrum.

BoatU.S. and other critics maintain the updated plan still risks harmful GPS interference. David Kennedy, BoatU.S. manager of government affairs, told Soundings that the FCC’s approval was a mistake that should be reversed. “The GPS signal exists within a quiet neighborhood on the spectrum,” Kennedy said, noting that satellites are far away and their signals are relatively weak, so regulators have traditionally kept that spectrum clear to preserve reliable positioning and timing services.

The L-band covers roughly 1.0 GHz to 2.0 GHz. Ligado plans to operate in frequencies near 1.5 GHz and 1.6 GHz, close to bands reserved for GPS. Proponents of the move, including senior government officials who argue that additional spectrum is essential for U.S. leadership in 5G, say the company’s modifications address earlier concerns and that only a limited subset of devices would be affected. Opponents counter that other countries are deploying 5G without encroaching on GPS allocations, and that Ligado’s transmissions could still result in widespread GPS outages.

Congressional pushback was swift and bipartisan. Lawmakers, including leaders from the House and Senate Armed Services committees, warned they would intervene to block or limit the decision. The Keep GPS Working Coalition, launched on June 23 with BoatU.S. as a founding member, represents a wide coalition of industries that rely on GPS—from aviation and agriculture to construction and transportation—and argues the FCC failed to fully weigh the risk to national security and critical infrastructure.

“In issuing the Ligado order, the FCC threw millions of Americans who depend on GPS in their everyday lives under the bus with undue haste and inadequate consideration,” said coalition spokesman Dale Leibach. The group notes that numerous federal agencies and departments—defense, transportation, commerce, interior, justice, homeland security, NASA, the National Science Foundation, the Coast Guard and the FAA—raised concerns about potential impacts on navigation, timing, and mission-critical systems. The Department of Defense has told Congress it believes interference could jeopardize operations and personnel.

If interference occurs as critics fear, GPS users—including recreational and commercial mariners—could experience complete signal loss rather than degraded position reports. It remains unclear which types or models of receivers would be most vulnerable, and whether newer devices might be less susceptible. Kennedy emphasized that testing has been limited and that it’s not known whether marine GPS units were adequately evaluated before the FCC’s approval. Boat owners could find themselves facing unexpected equipment failures without a clear path for recourse.

Legislative proposals are expected that would require Ligado to provide compensation to consumers and industries harmed by interference. Even if such remedies are enacted, Kennedy warned that practical recovery for individual boaters may be difficult. “We’re talking about a single private company with an interest in keeping their network on, and then there’s me, the boater,” he said. “All I know is that my device all of the sudden becomes unreliable. I don’t know how to go and get them to fix it.”

For now, Ligado has not activated the network at scale, and GPS continues to function as it has historically. Still, BoatU.S. recommends that mariners plan for a navigation environment in which GPS may not be the sole dependable source of position information. Using multiple navigation methods—such as radar, chartplotters with alternative inputs, paper charts, compass, and visual navigation techniques—will reduce risk until the full impact of any new transmissions is clear.

BoatU.S. plans to continue advocating for robust, reliable navigation and to press for federal oversight to protect public safety and economic security. “This is one of the oldest functions of the federal government,” Kennedy said, comparing modern navigation protection to historic investments in lighthouses. “This is something that we need the federal government for. This is a primary role that they need to do.”

This article originally appeared in the September 2020 issue.