The truth about 5G rollout in the US
A lot of misinformation has crept into the public arena regarding the implementation of 5G in the United States.
For many, the perception is that aviation has, at the last minute, woken up to the fact that 5G might interfere with radio altimeters. In turn, this has caused a delay in 5G antennas near airports. Aviation is therefore to blame for mobile users being deprived of the superior connectivity inherent in 5G technology.
Two main points highlight the errors in this view. First, the problem is far from last minute. Aviation has been stressing a potential issue for years. Essentially, the spectrum used for 5G is uncomfortably close to that used for radio altimeters – which not only tell aircraft how close they are to the ground but also feed critical information into other safety systems. When combined with a high-power output, it means 5G may potentially interfere with aircraft systems.
Aviation knew about the problem and repeatedly tried to stop the US auction of the relevant spectrum – which, despite objections, was eventually sold in February 2021 for tens of billions of dollars with AT&T and Verizon the main buyers.
The Federal Aviation Administration (FAA) makes this point clearly with its timeline:
Since 2015, the FAA and the world aviation industry jointly raised concerns and had ongoing technical discussions. In the World Radio Conference proposal, the proposal only supported an international mobile telecommunications (IMT – i.e. 5G) allocation in the 3.4 to 3.7 GHz spectrum – not the 3.7 to 3.98 GHz spectrum, which was ultimately sold off.
- In 2018, Boeing raised concerns and proposed a solution. Additionally, ICAO, the aviation arm of the United Nations, identified that any use of the bands near 4.2 to 4.4 GHz should be contingent upon radio altimeter studies.
- In 2018, the Air Line Pilots Association raised concerns to the US Federal Communications Commission (FCC).
In 2020, ahead of the auction for 5G C-Band, the FAA again raised concerns and asked for a postponement to collaborate on a solution. The NTIA, the federal government coordinator on spectrum disputes, failed to put the 2020 letter into the FCC’s docket.
Throughout 2021, the aviation industry continued to ask for additional collaboration and time in anticipation of the complications. The industry also held several meetings throughout the year to find solutions, including in June and October.
FAA Administrator Stephen M. Dickson’s recent testimony to the House Transportation and Infrastructure Committee noted: ““We have the safest aviation system in the world, and we don’t take that for granted. We have achieved this because we take actions to mitigate known and potential risks to safety. It’s why the FAA has been involved in a sustained effort since well before the 2020 spectrum auction to highlight and now mitigate potential 5G interference with critical flight systems.”
Different versions of 5G
The second point to make is that referring to the uncomplicated implementation of 5G in other countries is of little relevance. There are differences in spectrum, power, and antennae locations.
In Europe, for example, the spectrum is in the 3.4GHz to 3.8GHz range and power levels are at least 23% less than those permitted in the United States. In Australia, the power levels are 76% lower, and the spectrum is even further away from that used by radio altimeters. Canada has exclusion zones around airports and, like many other countries, also forces antennas to be tilted down.
Administrator Dickson’s testimony pointed this out. “5G and aviation have safely coexisted in other countries because power levels have been reduced around airports and the industries have worked together prior to deployment,” he said. “For years, we have been working to find a solution in the United States.”
There is a temporary delay in 5G rollout near airports in the US as the involved parties try to work out a solution. The power has also been turned down.
In the meantime, Alternative Means of Compliance (AMOC) allow flights to continue near affected airports on a case-by-case basis. AMOCs are very specific and last no longer than three months so are not a long-term solution.
New altimeters are in the pipeline and expected by 2023. But a lot of work remains to be done, especially concerning the US power output.
“We know from long experience that early and open data exchange between everyone—stakeholders and regulators— has proven to be critical to identify and mitigate safety risks,” stated Administrator Dickson. “Aviation remains the safest form of transportation because of our commitment to a data-driven process, and we will lean on it as we set new standards for altimeter performance in the new environment created by the 5G C-band deployment.
“Spectrum is a limited resource, but the demand is infinite and will likely increase in coming years. The FAA’s primary concern is and will always be the safety of the aviation system. But we firmly believe that, by working together, 5G and aviation can—and will—safely coexist.”