Buttigieg warns airlines to complete retrofitting planes to avoid 5G signal interference

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

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

The warning — in a letter by Buttigieg to the trade group Airlines for America — comes just before the AT&T, Verizon and other wireless carriers will be free to increase their C-band, 5G signal strength on July 1.

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

Some aviation experts believe that C-band signals are too close to the frequencies on the radio spectrum used by radio altimeters, which measure the height of an aircraft above the ground. The new altimeters are interference-safe, but some airlines have complained that a lack of equipment has prevented them from upgrading all of their aircraft.

It is not clear whether there could be major travel disruptions due to the spectrum dispute. When the issue first arose early last year, predictions of widespread problems proved wrong, although a small number of flights were canceled or diverted.

The Federal Communications Commission, which hands out 5G licenses to wireless companies, argues there is no risk of interference, while the Federal Aviation Administration has sided with the airlines. Under pressure from the Biden administration, the wireless companies agreed to delay the full rollout of their new networks until July 1.

The Department of Transportation, relying on information from airlines, says that more than 80% of the US fleet has been redeployed.