U.S. warns 5G wireless use could prompt flight diversions

By David Shepardson

WASHINGTON (Reuters) -The U.S. Federal Aviation Administration on Tuesday warned that interference from planned use of 5G wireless spectrum poses an air safety risk and could result in flight diversions.

The aviation industry and the FAA have raised concerns about potential interference of 5G with sensitive aircraft electronics like radio altimeters. AT&T and Verizon Communications in November agreed to delay the commercial launch of C-band wireless service until Jan. 5 after the FAA raised concerns.

The FAA issued a pair of airworthiness directives order the revision of airplane and helicopter flight manuals to prohibit some operations requiring radio altimeter data when in the presence of 5G C-Band wireless broadband signals.

One FAA directive on Tuesday said the "unsafe condition" posed by the planned use requires immediate action before the Jan. 5 deployment "because radio altimeter anomalies that are undetected by the aircraft automation or pilot, particularly close to the ground... could lead to loss of continued safe flight and landing."

The FAA reiterated in a statement on Tuesday that it believes the "expansion of 5G and aviation will safely co-exist." The agency added that the two directives "provide a framework... to gather more information to avoid potential effects on aviation safety equipment."

The FAA remains in discussions with the Federal Communications Commission, White House and industry officials about the precise contours of any limitations, which are expected to be outlined in the coming weeks in a series of notices.

It is not yet clear what airports or specific airplanes may be impacted. The FAA said notices will "be issued, as necessary, to state the specific areas where the data from a radio altimeter may be unreliable due to the presence of 5G C-Band wireless broadband signals."

AT&T and Verizon on Nov. 24 said they would adopt precautionary measures for at least six months to limit interference. But aviation industry groups said on Monday they were insufficient to address air safety concerns.

The wireless companies said they would take "additional steps to minimize energy coming from 5G base stations." The FAA said in its directives that "under the FCC rules adopted in 2020, base stations in rural areas of the United States are permitted to emit at higher levels in comparison to

other countries."

Wireless companies argue that there have been no C-Band aviation safety issues in other countries using the spectrum.

The FAA cited a 2020 report that concluded there is "a major risk that 5G telecommunications systems... will cause harmful

interference to radar altimeters on all types of civil aircraft — including commercial transport airplanes; business, regional, and general aviation airplanes; and both transport

and general aviation helicopters."

(Reporting by David Shepardson; Editing by Dan Grebler)