(Bloomberg) -- AT&T Inc. and Verizon Communications Inc. said they will roll out their new 5G service at temporarily reduced power in coming months to alleviate fears the signals may interfere with the electronics of jetliners and other aircraft.

The measures, offered Wednesday in a letter to the U.S. Federal Communications Commission, follow a warning to pilots from aviation regulators regarding the new service, and negotiations that involved federal agencies and the White House.

“We have voluntarily agreed to certain precautionary protection measures,” AT&T said in a statement. “Though there is no credible evidence that a legitimate interference problem exists, we agreed to take these additional steps to alleviate any safety concerns.”

It is one of the first signs of possible compromise after months of growing tension between the two sides. The parameters outlined by AT&T and Verizon may allow for more precise analysis of what risk the signals could pose. The mobile providers hadn’t directly shared their proposal with the Federal Aviation Administration or the aviation industry before filing it with the FCC.

The aviation and mobile industries have been at loggerheads in the unusually public dispute over the use of frequencies, which are increasingly in demand from new wireless technology. In this case, the 5G service would operate on a set of airwaves known as the C-Band that are to carry lucrative new services.

Aviation officials have said the new 5G signals could disturb safety equipment on aircraft, while the FCC and the mobile industry have said there is no evidence of a problem. Mobile providers previously said they’ll delay using the airwaves for a month, until early January.

AT&T and Verizon in their letter pledged to operate the new 5G service at reduced power everywhere for six months, with even lower power levels and limited antenna height near airports and along landing paths. Transmissions would also be limited for antennas pointed skyward and at locations near “public helipads,” the companies said.

The two companies outlined multiple precise limits to the power and direction of the frequencies they will use over the next six months, information the aviation industry has repeatedly requested.

The companies also opened the door to extending the restrictions beyond six months if “credible evidence emerges that real-world interference would occur if the measures were relaxed,” they said in the letter.

At the same time, the companies took pains to defend their initial plans, saying there was no evidence they posed a safety risk.

RTCA Inc., a Washington-based nonprofit that studies technical aviation issues, in a report last year concluded that the potential for interference created a safety hazard. But without detailed information on power levels and how cell tower antennas would be positioned, industry analyses had been forced to make worst-case assumptions, said four people familiar with discussions on the issue. They asked not to be identified because of the sensitive nature of the talks.

Certification requirements for radar altimeters, which bounce radio beams off the ground to determine an aircraft’s height, never anticipated risks of interference from nearby frequencies, so some models may not be protected from nearby C-Band waves. 

However, manufacturers of the devices have in recent years added more protections and studied the risks, so they should be able to determine whether the devices are susceptible to interference if more precise information on signal strength was provided, said one of the people familiar with discussions. 

Radar altimeters are critical for jetliners making landings in low visibility, and provide data to assist pilots during touchdown in clear weather as well. They also feed systems that warn pilots as they approach mountains shrouded in darkness or clouds and other technology that warns of potential midair collisions. Some aircraft, such as the Boeing Co. 737, use them to automatically set jet-engine power levels. 

The issue of interference may be even more thorny for helicopters, which operate at low altitudes near cell towers the majority of the time. The FAA mandates the use of radar altimeters on commercial helicopters and those carrying patients on emergency medical flights. Copter pilots using night-vision goggles must also have a working radar altimeter. 

The dispute represents a hitch in mobile providers’ pursuit of 5G airwaves to serve billions of connected homes, factories and gadgets with the latest generation of technology. AT&T and Verizon are in a race to catch up to T-Mobile US Inc., which is about a year ahead on 5G network deployment using other airwaves not suspected of causing interference.

Mobile carriers have permission to use the C-Band beginning Dec. 5. The FCC awarded wireless network providers access to the radio bands in a February auction. Verizon spent $45 billion on the airwaves in question, and AT&T devoted $23 billion in an FCC auction.

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