FCC Actions Compromise the GPS Spectrum and Safety Systems

By Christopher Freeze, Senior Aviation Technical Writer

In late April, the Federal Communications Commission (FCC) granted a license to build a ground-based 5G data network utilizing the radio spectrum adjacent to safety-critical global positioning system (GPS) and satellite communications used daily by ALPA members. The FCC granted this license to transmit to Ligado Networks (formerly LightSquared) over the objections of nearly every other U.S. government agency and more than 68 private organizations representing the interests of aviation, the military, first responders, trucking, maritime, meteorology, agriculture, and construction. 

ALPA’s Government Affairs Department immediately made stakeholders on Capitol Hill aware of ALPA’s concerns.

“GPS signals tend to be quiet and low-energy—like rustling leaves,” remarked Dr. Michael Griffin, under secretary of the Department of Defense for research and engineering, during a Senate Armed Services Committee (SASC) hearing on May 6 regarding the license. “By comparison, the noise produced by Ligado’s signal would be trying to hear those leaves through the noise of a hundred jets taking off.”

In a letter submitted to the SASC prior to the hearing, Capt. Joe DePete, ALPA’s president, pointedly stated, “Throughout its report and order, the FCC uses words like ‘possible’ and ‘feasible’ when talking about whether Ligado can operate. These aren’t the words you would want to hear your captain use when talking about successfully completing your flight the next time you’re sitting in the cabin. Aviation requires certainty and guaranteed performance from its systems.”

In mid-May, ALPA went further and filed a petition for reconsideration with the FCC. In the petition, Capt. Bob Fox, ALPA’s first vice president and national safety coordinator, characterized the FCC’s decision as “degrading the safety of airline operations and putting passengers, crews, and the safety of persons and property on the ground at additional risk in a way that the commission didn’t even try to measure or quantify.”

In addition to potential interference with GPS on aircraft ranging from unmanned aircraft systems to airliners, Ligado handsets also have the potential to interfere with controller-pilot datalink communications and automatic dependent surveillance-contract when operating in oceanic and remote areas.

Fox concluded by stating that while the development of 5G is an important investment in U.S. infrastructure, “the vulnerabilities to our aviation safety and security aren’t worth the risk, particularly for a band of spectrum that isn’t necessary to secure a robust 5G network.”

On May 22, several federal agencies formally asked the FCC to reconsider the license, citing GPS interference concerns.

In a related matter, on May 27 ALPA joined a coalition of private-sector aviation and aerospace organizations asking the FCC to reconsider parts of its C-Band order to protect aviation safety and revisit how it applies protections to adjacent band radio altimeter operations that are essential to safe air travel.

“The planned implementation of a 5G mobile wireless system in this frequency band doesn’t take into consideration existing users on nearby frequencies, including aviation,” said DePete in a statement supporting the petition for reconsideration. “Deploying 5G near the radio altimeter frequency—used on commercial aircraft—without adequate testing and validation that the protections are adequate could pose a serious threat to safe flight during critical operations such as landing during bad weather and fog.

“Additionally, the interference could render useless important safety equipment onboard aircraft such as the terrain awareness and warning system, which is required on all U.S. commercial aircraft and has led to zero passenger fatalities due to controlled flight into terrain for the past 15 years,” DePete observed. “ALPA urges the FCC to take an active role in ensuring a safe 5G deployment in this band.”

As Air Line Pilot went to press, the Ligado licensing issue and radio altimeter protection measures remain unresolved. However, ALPA and Congress aren’t relenting. Absent the FCC acquiescing to the formal requests by ALPA, federal agencies, and other coalition partners, the Association has urged its allies on Capitol Hill to include language regarding the Ligado license in the annual National Defense Authorization Act.

This article was originally published in the June 2020 issue of Air Line Pilot.

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