The agency is still studying whether those wireless networks will interfere with altimeters, which measure an aircraft’s height above the ground. Data from altimeters is used to help pilots land when visibility is poor.
The devices operate on a portion of the radio spectrum that is close to the range used by the new 5G service, called C-Band.
This week's FAA actions are part of a larger fight between the aviation regulator and the telecom industry. The telecom companies and the Federal Communications Commission say 5G networks do not pose a threat to aviation. The FAA says more study is needed.
The FAA is conducting tests to learn how many commercial planes have altimeters that might be vulnerable to spectrum interference. The agency said this week it expects to estimate the percentage of those planes soon, but didn't put a date on it.
“Aircraft with untested altimeters or that need retrofitting or replacement will be unable to perform low-visibility landings where 5G is deployed,” the agency said in a statement.
The order regarding Boeing 787s covers 137 planes in the U.S. and 1,010 worldwide. The 787 is a two-aisle plane that is popular on longer routes, including many international flights.
The FAA said that based on information from Boeing, the 787s might not shift properly from flying to landing mode if there is interference, which could delay the activation of systems that help slow the plane.
AT&T and Verizon have twice agreed to postpone activating their new networks because of concerns raised by aviation groups and the FAA, most recently after the FAA and Transportation Secretary Pete Buttigieg weighed in on the aviation industry's side. Buttigieg and FAA Administrator Stephen Dickson warned that flights could be canceled or diverted to avoid potential safety risks.
Under an agreement with the telecom companies, the FAA designated 50 airports that will have buffer zones in which the companies will turn off 5G transmitters or make other changes to limit potential interference through early July.
The 50 include the three major airports in the New York City area — LaGuardia, JFK and Newark Liberty — O’Hare and Midway in Chicago, Dallas/Fort Worth International, Bush Intercontinental in Houston, Los Angeles International and San Francisco.
That concession by the telecoms was modeled after an approach used in France, although the FAA said last week that France requires more dramatic reductions in cell-tower reach around airports.
David Koenig can be reached at www.twitter.com/airlinewriter