A new Federal Aviation Administration regulation prohibiting Boeing 747-8 freighters and all 777 widebody aircraft from landing at airports where 5G towers might interfere with onboard safety equipment could have a disproportionate impact on major cargo airlines like UPS, FedEx and Atlas Air.
The airworthiness directive issued Tuesday said the FAA has identified an additional hazard from interference with radio altimeters beyond creating a landing danger in low-visibility conditions. Specifically, the signal interference could result in altimeters delivering faulty data to flight computers that control the aircraft’s pitch and put it in an inappropriate “up-down” position regardless of weather conditions, which is “especially hazardous” at low altitude.
Other systems could also be compromised, which combined with the uncommanded, inappropriate pitch inputs, “could affect the flightcrew’s ability to accomplish continued safe flight and landing,” the directive said.
The document also covers 747-8 passenger variants. Boeing 747-400s and classic models are not covered.
Altogether there are about 336 aircraft under U.S. registry and 1,714 worldwide that are impacted by the rule, according to the FAA.
UPS Airlines (NYSE: UPS) operates 22 747-8 freighters, according to a fact sheet on its website. Atlas Air (NASDAQ: AAWW), the largest 747 operator in the world, has 10 747-8 cargo jets in its fleet, along with 14 777s. FedEx (NYSE: FDX) has 51 777 freighters, its latest quarterly report shows. Privately held Kalitta Air operates four 777s. DHL Express has 19 777s in its fleet, according to Planespotters.
United Airlines (NASDAQ: UAL) also has a large 777 fleet that has helped the carrier produce record cargo revenue during the pandemic as it works to restore full passenger service.
It’s not immediately clear whether the carriers will face any tangible operational problems. Spokespeople at Atlas, FedEx and UPS directed all 5G inquiries to Airlines for America, an industry lobbying group that declined to comment on the new airworthiness directive.
The three carriers could collectively experience up to 10,800 flight delays, diversions or cancellations per year at a cost of $800 million if 5G is rolled out without mitigating steps, the association said several weeks ago.
Radio altimeters are instruments that send out signals to precisely measure the distance to the ground or water and relay the information to multiple onboard systems. Overlapping signals can degrade its function, aviation experts say.
AT&T and Verizon launched fifth-generation (5G) wireless broadband service in 46 markets on Jan. 19 using frequencies in the C-band radio spectrum, but delayed turning on base stations near airports after the airline industry warned the White House of potential flight delays and cancellations to maintain safety.
T-Mobile’s nationwide 5G network does not use the C-band spectrum the FAA is concerned about.
Since the agreement, the FAA cleared more than three-quarters of the U.S. commercial fleet to perform low-visibility landings at airports where wireless companies deployed 5G towers, saying they were not vulnerable to interference. A new 2-mile safety buffer around airports in 5G markets further expanded the number of airports available to planes with previously cleared altimeters.
The FAA issued the new airworthiness directive after an evaluation by Boeing that many systems on the 747-8s and 777s, including the autothrottle, ground proximity warning and thrust reversers, rely on the altimeter. The evaluation followed an FAA directive in December calling for precautions in low-visibility conditions.
The directive doesn’t apply to landings at airports where the FAA has determined it is safe to land with approved altimeters in the 5G C-band environment. It also doesn’t apply to airports where 5G isn’t deployed.
Boeing 747-8 and 777 operators can request permission for alternative methods of compliance, such as having approved altimeter models. Newer altimeters have a tighter reception cone so their signals are not as prone to getting deflected by other frequencies, aerospace engineers say.
Aircraft equipped with altimeters from Thales have more limitations and face greater operational challenges, said an industry source who is not authorized to speak to the press.
The FAA said Jan. 20 it “is working diligently to determine which altimeters are reliable and accurate where 5G is deployed in the United States. We anticipate some altimeters will be too susceptible to 5G interference.”
The 5G airworthiness directive for the 747s and 777s will officially be published in the Federal Register on Thursday.