What You Need to Know About the 5G Risk to Aircraft

Flights have been cancelled and airlines warn of chaos in US airspace as 5G rolls out. Could this have been avoided?

Episode Summary:

5G is the much-anticipated high-frequency wireless technology that delivers high-bandwidth data with very little latency. It’s a popular technology that delivers high value services such as video streaming directly to handheld devices but operates on frequencies that are very close to those used by critical aircraft systems, notably radar altimeters. Radar altimeters measure the height of aircraft above ground level, and they’re a fundamental instrument for both autopilot operation and piloted flying of airplanes to safe landings. Today’s commercial airplanes can land in reduced or even no visibility thanks to high levels of automation. Interference from 5G signals has caused significant flight disruptions in US airspace, despite the years of lead time before the actual rollout of 5G services. Why? Jim Anderton comments. 

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Transcript of this week’s show:

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We all know that information is power. Data is everything that, and everything from our smart phones to quantum computers handle more of it, faster than the science-fiction of 30 years ago could even imagine. But processing data is always dependent on moving data, and in today’s wireless world, the need for speed has spawned 5G technology. 

Put simply, 5G is a radio frequency technology that uses short wavelength radiation to encode more information per unit time then was possible with older, lower frequency radio. Higher frequency is desirable, for many applications and to prevent crosstalk chaos, the FCC in the US allocates bandwidth with an auction process. 5G operates in a range of frequencies called C-band, which in the US is a range of radio frequencies between 3.7 and 4.2 GHz. This is high-frequency stuff, and many competing interests operate devices that use those frequencies, including everything from induction heating and nuclear fusion research to baby monitors and, unfortunately, radar altimeters. 

What’s a radar altimeter? Is the primary instrument used by commercial aircraft to determine how high an airplane is above the ground. It’s a fundamental instrument in aviation, and it’s vital in this day of blind landing capability and scheduled airliner operations in conditions of low visibility. As the name implies, radar altimeters work like a radar set except pointed downward. High-frequency radiation is transmitted down from the airplane, is reflected by the ground and received back at the airplane. The instrument then uses time-of-flight and frequency shift to infer altitude with precision and accuracy that can even allow completely blind landings in commercial service. It goes without saying that other transmissions on nearby frequencies have the potential to jam the signals, with potentially disastrous effects for aircraft approaching a runway. 

Not all aircraft have radar altimeters that are susceptible to 5G interference, and the FAA has already approved most Airbus aircraft and almost all current Boeing airplanes as safe in 5G regions. The effect on regional airliners is still under review by the FAA, and regional jets not only feed the major hubs in the US, but they form an increasing part of point-to-point scheduled service as well. What happens if flights are restricted to good weather only because a 5G? Well, chaos. The strange thing is that in Japan and Europe, 5G has already rolled out without issues for aviation.  

In France for example, 5G signal strength is 2.5 times lower than in the US, and 5G safety buffer zones around airports are restricted to interference over the last 96 seconds of final approach, compared to 20 seconds in the US.  France requires that 5G antennas angled downward to minimize interference. Mitigation efforts in the US are expected to be similar at least in the short term, while the FAA approves avionics and test procedures to clear more aircraft types. 

One consequence of these regulatory differences is that the French model would require more transmitters to deliver the same service in areas near airports. None of this is rocket science, and it surprises me that with something like four years of study ahead of the 5G rollout, that this is even an issue. Everyone has known that 5G was coming for years. It’s almost as if one branch of government doesn’t communicate well with another. 

They’ll fix this, simply because they have to, but in the meantime for those of us who ride behind the cockpit, it’s important to know two things: one is that the cell phone in your pocket is not the source of the trouble, it’s the network transmitters. And the other is that the FAA is simply not going to allow commercial aviation to operate where 5G signals can disable aircraft systems. 

That’s nice, but it’s cold comfort when your flight is cancelled due to weather. 

Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.