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Explained: Why airlines in the US fear 5G rollout near airports

Airlines fear that 5G signals could interfere with devices used during landing


Telecom majors AT&T and Verizon have decided to delay rollout of new 5G service near key airports after the largest airlines in the US raised concerns that the service would interfere with aircraft technology and cause widespread flight disruptions.

As per a deal, mediated by the Federal Administration, the telecoms agreed to reduce the power of their networks near 50 airports for six months, similar to wireless restrictions in France. In exchange, the FAA and the Transportation Department promised not to further oppose the rollout of 5G C-Band.

Why are Airlines concerned?

The Federal Aviation Administration (FAA) expressed fears that the 5G signals could possibly interfere with the radio altimeters used in automated aircraft landings. 

FAA Administrator Stephen Dickson asked the telecom companies for delay, warning of “unacceptable disruption” to air service.

AT&T CEO John Stankey and Verizon CEO Hans Vestberg rejected the request in a letter that had a scolding, even mocking tone. But they had second thoughts after intervention that reached the White House. The CEOs agreed to the second, shorter delay but implied that there would be no more compromises.

AT&T and Verizon say their equipment will not interfere with aircraft electronics, and that the technology is being safely used in 40 other countries. However, Airlinea are worried that there could be some cancellations and delays because of limitations of equipment on certain planes. 

Delta Air Lines said there could be issues with flights operating in bad weather because of airport restrictions that regulators issued last week, when the 5G rollout appeared to be on schedule. 

The CEOs of 10 passenger and cargo airlines including American, Delta, United and Southwest say that 5G will be more disruptive than earlier thought. That is because dozens of large airports were subject to flight restrictions announced last week by the Federal Aviation Administration if 5G service was deployed nearby. The CEOs added that those restrictions wouldn’t be limited to times when visibility is poor.

“Unless our major hubs are cleared to fly, the vast majority of the traveling and shipping public will essentially be grounded. This means that on a day like yesterday, more than 1,100 flights and 100,000 passengers would be subjected to cancellations, diversions or delays,” the CEOs said in a letter Monday to federal officials. “To be blunt, the nation’s commerce will grind to a halt.”

C-Band: Avionics and 5G

The new 5G wireless service uses a segment of the radio spectrum that is close to that used by altimeters, which are devices that measure the height of aircraft above the ground. Altimeters are used to help pilots land when visibility is poor, and they link to other systems on planes.

The C-band is a radio frequency band from 4 to 8 GHz.

The spectrum used by aeronautical navigation systems runs between 4.2 and 4.4 GHz. This spectrum allocation facilitates transmission of information to and from aircraft altimeters, especially when they operate below 2500 feet. 

The spectrum for 5G in the US is between 3.7 and 3.98 GHz, which is close to the spectrum used by aeronautical navigation systems. The airlines fear that 5G networks operating in the C-band may cause harmful interference to radio altimeters.

The telecoms, the Federal Communications Commission’s (FCC) and their supporters argue that C-Band and aircraft altimeters operate far enough apart on the radio spectrum to avoid interference. They also say that the aviation industry has known about C-Band technology for several years but did nothing to prepare—airlines chose not to upgrade altimeters that might be subject to interference, and the FAA failed to begin surveying equipment on planes until the last few weeks.

What's the solution

The telecommunications companies said they would delay turning on 5G cell towers within a 2-mile radius of runways designated by federal officials till the White House finds a permanent solution.

Randall Berry, a professor of electrical and computer engineering at Northwestern University, likened the interference issue to two stations that overlap on the radio dial. The FCC-determined separation “may be be enough for some (altimeters) but not for others,” he told the Associated Press. One solution could be outfitting all altimeters with good filters against interference, Berry said, although there could be a fight over who pays for that work—airlines or telecom companies.

(With inputs from AP via PTI)