American airlines collectively block airports from opening C-band 5G. What are they afraid of?-EEWORLD

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According to CNN recently, several international airlines said they will cancel flights to the United States starting Wednesday due to uncertainty about whether there will be interference between the new 5G mobile phone services in the United States and important aircraft technology.

According to reports, Emirates, Air India, All Nippon Airways and Japan Airlines have all announced cuts to flights to the United States, citing this issue. The Federal Aviation Administration of the United States has previously warned that 5G signals could interfere with the radio altimeter in aircraft, causing a catastrophic crisis.

Domestic airlines in the United States took action earlier. On January 17, the CEOs of 10 large passenger and cargo airlines in the United States, including American Airlines, Delta Airlines, Southwest Airlines, and United Airlines, wrote a joint letter to the White House, requesting a postponement of the deployment of new 5G networks at airports.

Why does 5G service, which is widely used in some airports in Europe and Asia, cause such controversy in the United States?　

The Associated Press and Reuters quoted analysis from international aviation industry insiders in their reports that C-band 5G network services have been widely launched at airports in dozens of countries in Europe and Asia, and no security issues have been found. The U.S. aviation industry is so entangled because the technical standards set by the United States are "unique."

The operating frequency band of the radio altimeter on the aircraft is 4.2 to 4.4 GHz, while the C-band 5G resources auctioned by the US government are in the 3.7 to 3.98 GHz band, which is relatively close. In Europe, the European Union set the 5G mid-band at 3.4 to 3.8 GHz in 2019, and this band has been auctioned and applied in many European countries.

Technically, 4.2GHz is the lowest end of radio altimeter frequencies, still more than 200MHz away from the highest C-band spectrum frequencies (up to 3.98GHz), and is perfectly safe. But some experts disagree, citing a phenomenon called bandwidth pollution. As Interesting Engineering explains, highly concentrated signals in a given frequency range can "bleed through" into higher frequencies, causing at least some interference. This is similar to the light pollution problem, where it's hard to see the stars at night when you're close to a city. For example, you might be 20 miles outside a large city, but because of the millions of lights in the city, it's hard to see the stars in the night sky. While the FCC says it has studied the issue and isn't sure it will happen, a 2020 study published by the Radio Technical Committee for Aeronautics (RTCA), an independent technical standards organization representing the air transportation industry, suggests that 5G in the C-band spectrum does have the potential to cause "harmful interference" to radio altimeters.

From a political perspective, the current and previous administrations in particular have put pressure on the FCC to quickly expand 5G technology in the U.S. However, most U.S. carriers’ 5G deployments have been a mess from the start, and the FCC certainly doesn’t want to take full responsibility for it.

When U.S. carriers began rolling out 5G a few years ago, they took a very different approach.

Verizon pursues coverage speeds, deploying millimeter wave transceivers in major urban centers across the country. This allows them to have speeds in the 500Mbps to 2Gbps range, but the problem is that 99% of Verizon customers are not getting 5G at all.

T-Mobile took the opposite approach, aiming to expand coverage so that its customers get a "5G" indicator on their devices, even if the speed boost is negligible. T-Mobile primarily uses 600MHz spectrum to achieve this, so it can quickly expand 5G coverage without having to build too many cell towers. The result is that T-Mobile became the first US carrier to have 5G coverage in all 50 states.

AT&T has taken a middle ground, choosing not to take either approach. Perhaps having learned from the failure of 5G Evolution, it has decided to remain silent on 5G rollout, taking a slow and steady approach to nationwide rollout using a mix of mmWave and sub-6GHz technologies.

The European Aviation Safety Agency, whose jurisdiction includes 31 European economies, issued a statement on December 17 last year saying that the dispute over the so-called "5G frequency band interference" is limited to the US aviation industry, and "at this stage, Europe has not found any unsafe interference risks."

In Asia, South Korea's 5G mobile communications use a frequency band of 3.42 to 3.7 GHz, and has never reported any "radio wave interference" issues since it was put into commercial use in April 2019.

According to materials filed by the Cellular Telecommunications Industry Association with the Federal Communications Commission, "mobile operators in nearly 40 countries in Europe and Asia are using C-band 5G networks and have never reported that radio altimeters operating in the internationally used 4.2 to 4.4 GHz frequency band are affected."

What is the crux of the US “5G storm”?

Regarding this controversy, Bloomberg News in the United States pointed out that the continuous delays in 5G deployment reflect the damage caused by regulatory uncertainty and the failure of management by the Biden administration.

Since 5G officially started commercial use in 2019, all countries have accelerated the deployment of 5G networks. As a major communications country, the United States has taken the lead in the 4G era, but its 5G deployment is quite slow.

Wang Yanan, editor-in-chief of Aviation Knowledge magazine: Fundamentally speaking, this is a failure of coordination among various government departments in the process of promoting 5G in the United States. In the process of promoting 5G, there must be safety considerations. At least the Federal Aviation Administration and the United States Communications Regulatory Commission should consult with each other and complete the testing work, upgrades and some adjustments to civil aviation safety regulations in advance before promoting 5G. But in fact, it is obvious that these works are done in a rather chaotic manner.

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