Buttigieg warns airlines to finish retrofitting planes to avoid interference from 5G signals

Transportation Secretary Pete Buttigieg warned the nation’s airlines Friday that flights could be disrupted starting next week because some planes lack updated equipment to prevent interference from transmissions by wireless companies.

Buttigieg said that only planes retrofitted with the right equipment will be allowed to land when visibility is poor, such as during bad weather.

The warning — in a letter from Buttigieg to trade group Airlines for America — comes just before AT&T, Verizon and other wireless carriers will be free to boost the power of their C-Band, 5G signals on July 1.

Airlines have told the government they are having trouble getting equipment to retrofit planes because of supply-chain problems. Still, the industry trade group said airlines are confident they will avoid disruptions.

Some aviation experts believe that C-Band signals are too close on the radio spectrum to the frequencies used by radio altimeters, which measure the height of a plane above the ground. Newer altimeters are protected from interference, but some airlines have complained that a shortage of the devices has prevented them from upgrading all their planes.

It’s unclear whether the spectrum conflict could cause major travel disruptions. When the issue first arose early last year, predictions of widespread problems turned out to be wrong, although a small number of flights were canceled or diverted.

The Federal Communications Commission, which granted the 5G licenses to the wireless companies, contends that there is no risk of interference, while the Federal Aviation Administration has taken the airlines’ side. Under pressure from the Biden administration, the wireless companies agreed to delay the full rollout of their new networks until July 1.

The Transportation Department, relying on information from airlines, says more than 80% of the U.S. fleet has been retrofitted.