Airline passengers walk inside the Tampa International Airport
Airline passengers walk inside the Tampa International Airport as airports around the country are awaiting for Verizon and AT&T to rollout their 5G technology, in Tampa, Florida, U.S., January 19, 2022. Reuters

The U.S. Federal Aviation Administration (FAA) said Monday it is proposing a requirement that passenger and cargo aircraft in the United States have 5G C-Band-tolerant radio altimeters or install approved filters by early 2024.

Concerns that 5G service could interfere with airplane altimeters, which give data on a plane's height above the ground and are crucial for bad-weather landing, led to disruptions at some U.S. airports earlier this year.

The proposed airworthiness directive, which would take effect in February 2024, is similar to one that took effect in December 2021, prohibiting passenger and cargo flight operations in the vicinity of 5G C-Band wireless transmitters unless the FAA specifically approved them.

The FAA is also proposing a requirement that airlines revise airplane flight manuals to prohibit low-visibility landings after June 30 unless retrofits have been completed on that airplane.

Verizon and AT&T in June voluntarily agreed to delay some C-Band 5G usage until July 2023 as air carriers work to retrofit airplanes to ensure that they will not face interference. The December 2021 FAA directive relied on the voluntary agreement.

Some international airlines have privately expressed reluctance to install filters absent a legal requirement from the FAA, officials told Reuters.

Airlines for America, a trade group representing American Airlines, Delta Air Lines, United Airlines and others, said "carriers are working diligently to ensure fleets are equipped with compliant radio altimeters, but global supply chains continue to lag behind current demand. Any government deadline must consider this reality."

Wireless group CTIA said "the FAA's schedule for altimeter updates is reasonable and practical. 5G in the C-band coexists safely with air traffic."

FAA acting Administrator Billy Nolen in October sought a delay in some 5G C-Band transmissions from smaller operators over aviation safety concerns.

Nolen said in an Oct. 21 letter the agency wanted the Federal Communications Commission (FCC) to mandate the voluntary mitigations AT&T and Verizon had agreed to earlier this year to 19 smaller telecoms and other spectrum holders.

Airline CEOs in January 2022 had warned of an impending "catastrophic" aviation crisis that could ground almost all traffic because of the 5G deployment.

A deal struck shortly before a 2022 deadline did not prevent dozens of foreign carriers from canceling international flights to the United States.

Emirates airlines cancels flights at Logan Airport in Boston
A Spirit airlines flight takes off from Logan Airport, amid concerns about 5G networks interfering with some airplane instruments, in Boston, Massachusetts, U.S., January 19, 2022. Reuters