Airlines Face $4 Billion Equipment Charge as Spectrum Sale Looms

US aviation authorities proposed rules that could require airlines to spend billions of dollars replacing or updating critical flight safety equipment to accommodate the sale of new wireless spectrum mandated in President Donald Trump’s signature tax and spending package.

The Federal Aviation Administration said the regulations, released on Monday, would require airlines to upgrade radio altimeters — instruments that measure a plane’s altitude — so that they are able to withstand interference from wireless signals across neighboring spectrum bands.

The FAA estimates “the total undiscounted cost” to retrofit planes with the new equipment will be $4.49 billion. The ...