The issue at hand is a planned rollout of new C-band spectrum that could bolster existing 5G coverage.

Recall that Pete Buttigieg, U.S. Transportation Secretary and Steve Dickson, the head of the Federal Aviation Administration (FAA) had asked AT&T and Verizon Communications to delay the planned introduction of new 5G wireless service over aviation safety concerns.

In a letter last Friday seen by Reuters, Buttigieg and FAA Administrator Dickson asked John Stankey, AT&T chief executive and Hans Vestberg, Verizon chief executive, for a delay of no more than two weeks as part of a “proposal as a near-term solution for advancing the co-existence of 5G deployment in the C-Band and safe flight operations.”

On Friday, the FAA announced that it had reached an agreement with the carriers. Although AT&T and Verizon pledged to create a “buffer zone” of two miles around some airport runways, the new announcement suggests that the two sides were working on a longer-term solution.

In a statement, the FAA said it “appreciates” the strong communication and collaboration from telecom companies. It added that it provided more precise data about the location of wireless transmitters, as well as deeper dives into how 5G signals can interact with sensitive aircraft components.

“The FAA used this data to determine that it is possible to safely and more precisely map the size and shape of the areas around airports where 5G signals are mitigated, shrinking the areas where wireless operators are deferring their antenna activations,” the FAA said. “This will enable the wireless providers to safely turn on more towers as they deploy new 5G service in major markets across the United States.”

In addition to the FAA, airlines have also expressed concerns about the 5G rollout. A joint letter signed by 13 major airline operators earlier in January warned of “catastrophic disruption” if the rollout continued as planned.

C-band spectrum is well-suited to aid in expanding 5G service in the U.S. The spectrum is currently used in countries like France with no reports of disruption to airline service.

In a letter last Friday seen by Reuters, Buttigieg and FAA Administrator Dickson asked John Stankey, AT&T chief executive and Hans Vestberg, Verizon chief executive, for a delay of no more than two weeks as part of a “proposal as a near-term solution for advancing the co-existence of 5G deployment in the C-Band and safe flight operations.”

The aviation industry and FAA have raised concerns about potential interference of 5G with sensitive aircraft electronics like radio altimeters that could disrupt flights.

“We ask that your companies continue to pause introducing commercial C-Band service for an additional short period of no more than two weeks beyond the currently scheduled deployment date of January 5,” the letter says.

Verizon and AT&T both said they received the letter and were reviewing it. Earlier Friday the two companies accused the aerospace industry of seeking to hold C-Band spectrum deployment “hostage until the wireless industry agrees to cover the costs of upgrading any obsolete altimeters.”

Buttigieg and Dickson said under the framework “commercial C-band service would begin as planned in January with certain exceptions around priority airports.”

The FAA and the aviation industry would identify priority airports “where a buffer zone would permit aviation operations to continue safely while the FAA completes its assessments of the interference potential.”

The government would work to identify “mitigations for all priority airports” to enable most “large commercial aircraft to operate safely in all conditions.” That would allow deployment around “priority airports on a rolling basis” — aiming to ensure activation by March 31 barring unforeseen issues.

The carriers, which won the spectrum in an $80 billion government auction, previously agreed to precautionary measures for six months to limit interference.

On Thursday, trade group Airlines for America asked the Federal Communications Commission (FCC) to halt deployment of new 5G wireless service around many airports, warning thousands of flights could be disrupted: “The potential damage to the airline industry alone is staggering.”

Sara Nelson, president of the Association of Flight Attendants-CWA, representing 50,000 flight attendants at 17 airlines, called the Transportation Department proposal “the right move to successfully implement 5G without using the traveling public (and the crews on their flights) as guinea pigs for two systems that need to coexist without questions for safety.”

Wireless industry group CTIA said 5G is safe and spectrum is being used in about 40 other countries.

House Transportation Committee chair Peter DeFazio Friday backed the airline group petition warning “we can’t afford to experiment with aviation safety.”