5G network deployment in the U.S. spawns a cluster of disruption

Something is going on with Runway 10L at Palm Beach International Airport in Florida. Last week, a Bombardier-built CRJ200 regional jet on final approach had the strangest thing happen.

The aircraft’s radar altitude abruptly ran down to zero, causing repeated loud aural warnings: PULL UP WHOOP WHOOP DON’T SINK TOO LOW GEAR. The flight landed without incident in good weather, but it wasn’t the first time. “Exact same location multiple times the past two weeks,” the pilot, who was on the flight deck for both anomalies, told The Air Current.

The incidents were reported to the Federal Aviation Administration. It’s not known definitively if the radar altimeter behavior was related to pre-deployment testing of 5G telecommunication technologies, but the unexplained incident underscored the fears of aviators, as well as the confusion and increasing disruption that is now befalling U.S. commercial aviation.

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International airlines like Emirates, Air India, Japan Airlines and All Nippon Airways have cancelled flights to select cities, citing the 5G C Band interference risk to their aircraft. Boeing on Monday night sent a so-called multi-operator message to carriers flying 777 and 747-8s and “recommends operators do not operate 777 airplanes on approach and landing to U.S. runways” with 5G C Band notices starting on January 19 unless there is an alternative means of compliance with FAA directives, according to guidance reviewed by The Air Current.

“The above recommendation has been determined through the Boeing Safety Review Board and engineering pilot evaluation based on the uncertainty of the 5G operating environment,” the company wrote. The review board meeting was held on January 15. “Boeing recommends that operators develop contingency plans for their operations.”

Boeing referred comment to the FAA after saying, like Airbus, it was working with an industry coalition to address the 5G deployment issue with U.S. regulators. The FAA did not respond to questions about the reported incident in Palm Beach.

Scaling back activation

The U.S. 5G network will be formally activated by Verizon and AT&T on January 19 in 32 states, but both companies plan to limit the deployment around major U.S. airports. “We have voluntarily decided to limit our 5G network around airports,” Verizon said in a statement Tuesday. AT&T said the same. “At our sole discretion we have voluntarily agreed to temporarily defer turning on a limited number of towers around certain airport runways as we continue to work with the aviation industry about our 5G deployment.”

President Joe Biden in a statement thanked both companies for delaying their implementation at a “limited set of locations” to avoid any disruption around “key airports”, but that localized stand down came after Boeing’s Monday-evening recommendation causing international carriers to cancel flights to certain U.S. destinations.

“We recognize the economic importance of expanding 5G, and we appreciate the wireless companies working with us to protect the flying public and the country’s supply chain. The complex U.S. airspace leads the world in safety because of our high standards for aviation, and we will maintain this commitment as wireless companies deploy 5G,” said U.S. Transportation Secretary Pete Buttigieg in a statement.

Yet, the disruption is expected to continue even with the Verizon and AT&T move, according to industry officials. The airworthiness directive issued by the FAA on December 7 warning of disruption from 5G signals to radio altimeters is the guidance operators fly with, not a voluntary shift by telecom companies. “FAA limits define what can or cannot be done,” said one industry official.

Now, the FAA is scrambling to add precision to its blanket directive from December, clearing each aircraft, its specific make and model of radio altimeter, and each airport and its surrounding 5G networks for safe operation.

The FAA on Monday said it had cleared operations with two radio altimeter models found on Boeing 737, 747, 757, 767, MD-10/-11 and Airbus A310, A319, A320, A321, A330 and A350 models. Those cleared aircraft account for about 45% of the U.S. airline fleet.

Notably missing from the FAA’s list are the 777 and 787, the backbone of the international fleet. The CEOs of the country’s largest airlines through Airlines4America, its chief lobbying group, wrote to the White House, FAA, DOT and Federal Communications Commission that “airplane manufacturers have informed us that there are huge swaths of the operating fleet that may need to be indefinitely grounded. In addition to the chaos caused domestically, this lack of usable wide body aircraft could potentially strand tens of thousands of Americans overseas.”

Last month, both Boeing and Airbus urged telecom networks to delay the 5G implementation, while they evaluate any potential impact on radio altimeters that are integral to not only establishing a reliable height off the ground, but are part of the flight control and propulsion logic on aircraft like the 787 that are needed on every flight, regardless of weather conditions and visibility.

The chaotic deployment is a black eye for the U.S. aviation regulator at a time when its focus since 2019 has been on the grounding of Boeing’s 737 Max and coordinating the jet’s return to service.

This didn’t creep up on the aerospace industry nor Congress, whose documented concerns to the FCC about interference date back to 2018 and repeated published warnings. The Radio Technical Commission for Aeronautics (RTCA) issued an October 2020 report saying that the 5G frequencies operating “in the [2,700 to 3,900 Mhz] band will cause harmful interference to radar altimeters on all types of civil aircraft” and revealed a “major risk” to safe aviation operations.

Radio altimeters on aircraft operate in the nearby 4,200- to 4,400-MHz frequency band, but regulators around the world have recommended a “guard band” around aviation operations to prevent any interference.

The telecom companies, which purchased the rights to the spectrum for $81 billion without restrictions in February 2021, were sharply critical of the U.S. aviation regulator and industry. “They have not utilized the last two years they’ve had to responsibly plan for this deployment,” said AT&T in its Tuesday statement. 

Both companies have pointed to the successful deployment of 5G networks in 40 countries, however, they have not been enacted without restrictions around airports. In October, Canada’s government told its telecom companies to offer a 550 to 700 MHz buffer for deployment of 5G networks around its largest airports, surprising the providers who spent $9 billion in July procuring the spectrum band for the next generation network, according to an October report in the Toronto Star.

The FAA noted on its 5G guide that other countries, such as France, have implemented larger airport buffer zones and antennas are deliberately tilted downward to limit harmful interference with aircraft, in addition to lower 5G power levels.

Elan Head and Howard Slutsken also contributed to this report.

Write to Jon Ostrower at jon@theaircurrent.com