5G deployment near US airports slowed for now

5G deployments are proceeding around the country, albeit more slowly, after a partial agreement between the FCC and the FAA about the potential danger of 5G transmissions generated too strong and too close to airports on bandwidths adjacent to the spectrum used by airplane altimeters.

President Biden announced that Verizon and AT&T had agreed to slow deployments of 5G around major airports after consultation with the Department of Transportation, in order to assuage concerns over air travel safety.

At issue is potential interference between newly opened 5G spectrum in the 3.7GHz range and radioaltimeter equipment on older aircraft. While there’s some separation between the 3.7GHz 5G signals, which top out at 3.98GHz, and the bottom of the 4.2GHz range used by the avionics equipment, the FAA and the airline industry remain concerned over potential interference that, theoretically, could prevent affected aircraft from landing safely in low-visibility conditions.

Wireless network deployments in similar bands have proceeded without incident in other countries, most notably France, though carriers have also had to limit the power of their transmissions near airports.

The FAA announced on Jan. 20 that roughly 78% of the U.S. commercial fleet was cleared to perform low-visibility landings at airports near new 5G deployments, but work remains to be done on clearing the rest of America’s commercial aircraft.

“The FAA is working diligently to determine which altimeters are reliable and accurate where 5G is deployed in the United States,” the agency said in a statement. “We anticipate some altimeters will be too susceptible to 5G interference. To preserve safety, aircraft with those altimeters will be prohibited from performing low-visibility landings where 5G is deployed because the altimeter could provide inaccurate information.”

The FAA’s caution is understandable, according to Dr. M. Cenk Gursoy, a professor of electrical engineering and computer science at the University of Syracuse, but it’s unclear whether the troublesome interference would actually be an issue.

“Nothing should be beyond…3.98GHz,” said Gursoy. While there could be some spillover of 5G signals past the strict boundaries set by the FCC, Gursoy is doubtful that it could affect aircraft systems operating in spectrum that is more than 200MHz higher in frequency.

“From my point of view, there’s a substantial separation between the bands,” he said. “I don’t immediately feel the kind of world-is-falling-apart type of scenario.”

US wireless carriers have pledged to limit signal strength from 5G base stations near airports, but this has apparently failed to mollify some of the major players in the aviation industry, including the president of Emirates Airlines, who said in an interview with CNN that the situation is “one of the most delinquent, utterly irresponsible” he’s ever seen, and said that he’d suspend all service to the US until the perceived problems have been solved.