A 5G deadline could ground some US flights starting July 1st

Planes without compatible altimeters won't be allowed to fly in low visibility.

Starting July 1st, any planes without retrofitted sensitive radar altimeters across the US can't land in low visibility, a stipulation that could cause delays for travelers, The Wall Street Journal reports. To be clear, this is not addressing an ongoing safety issue — the deadline aligns with US wireless companies increasing the power of their 5G networks, potentially creating greater interference for any aircraft without the necessary equipment.

The 5G boost comes after years of delays and debates between the Febderal Communications Commission (FCC) and the Federal Aviation Administration (FAA) due to concerns about the signals' impact on radio waves that judge how far a plane is from the ground. Carriers first planned to increase the power of their networks in January 2022, delayed it until July 2022 and finally found a compromise with the FAA to proceed on July 1st, 2023.

About 80 percent of domestic aircraft have undergone the upgrade, with some top carriers still needing to finish their fleet. Delta, for instance, will have 190 planes left to bring up to par, while JetBlue will have 17 — something the Airlines for America trade association blames on supply chain problems. United, Southwest and American Airlines have all reported they will have no outstanding planes by the deadline. Another 65 percent of aircraft flying from international destinations into the US have up-to-date altimeters, with airlines poised to use those options whenever possible.

"There's a real risk of delays or cancellations," Buttigieg said. "This represents one of the biggest—probably the biggest—foreseeable problem affecting performance this summer." The level of impact will depend mainly on the weather, but fortunately, there won't be snowstorms anytime soon. All planes in the US will need an updated altimeter by February 2024, regardless of visibility conditions.

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