Leading up to AT&T and Verizon’s rollout of their upgraded 5G C-band equipment, it seemed like the sky was falling.
For years, the Federal Aviation Administration and aviation organizations had expressed concerns that the improved mobile technology could disrupt vital safety equipment on aircraft, while the FCC and airlines insisted it was safe, pointing to similar implementations in dozens of other countries. Even after several delays, last-minute deals continued to be struck between airlines and regulators, with airlines uniting to warn that the activation could cause “catastrophic disruption” to air traffic and shipping. Several international airlines have canceled flights to certain US airports.
But just days after the airlines turned on their equipment, the CEOs of United and American Airlines told investors things seemed mostly fine, according to CNN. The large-scale delays and cancellations hadn’t materialized, and the American Airlines CEO is even said to have predicted, “I don’t think you’ll see any material disruption because of this.”
But while many of the large jets used by major airlines have been deemed safe by the FAA (in most circumstances – on Tuesday the regulator issued a directive “banning Boeing 747-8, 747-8F and 777 aircraft). landing at airports where 5G interference may occur”), the story is not necessarily the same for the smaller regional aircraft used for connecting flights or landing at more rural airports.
The saga revolves around a device that almost every aircraft is equipped with: the radar or radio altimeter. His job is to find out how far the plane is from the ground and to help pilots land in bad weather with poor visibility. “The radar altimeter gives you very fine altimetry readings when you get really close to the ground, which is very useful, especially in instrument conditions where you may not be able to see the ground,” said Pat Anderson, a mechanic, pilot, professor of aerospace engineering and director of the Eagle Flight Research Center.
“In older generation aircraft, that was kind of an isolated system that the pilot would read and interpret,” he explained. However, in more modern aircraft, that data can be accessed and used by many other systems, such as brakes or spoilers. “As we get more integrated aircraft, there could be a cascade effect where it not only negates the pilot information, but also affects other aircraft systems upon landing.”
Given that altimeters are so crucial, the FAA has taken very seriously the concern that they could incorrectly pick up 5G C-Band signals. It posted announcements restricting how planes could land at airports where the rollout took place and said it would release specific models of altimeters that would be used at those airports. It’s worth noting that the FAA says it should re-evaluate approvals each month, based on how the airlines roll out their service.
These limitations are gospel, but they are not necessarily tied to the material situation. “Whatever Verizon, AT&T do, it really doesn’t matter,” said Jon Ostrower, editor-in-chief of The airflow, an online publication about the aviation industry. “Verizon could have literally shut down the entire 5G network nationwide on Wednesday, and it wouldn’t have mattered because the FAA had already issued its airworthiness directive.”
When the FAA began approving altimeters, the process seemed to move relatively quickly: On Jan. 16, it announced that about 45 percent of the U.S. commercial fleet had been cleared to land at “many of the airports” where 5G C- tape was used. By January 20, that number had risen to 78 percent and apparently applied to all U.S. C-band airports. On January 25, the FAA estimated that 90 percent of the U.S. commercial fleet had cleared an altimeter for “most poorly visible approaches in 5G deployment.”
But according to Faye Malarkey Black, the president and CEO of the Regional Airline Association, “about 53 percent of the regional fleet” either not approved or has limited approvals that do not include different airports.
The RAA, which represents the regional airlines that fly for United, Delta, American, Alaska and more, does not expect the FAA to make additional revisions at this time unless other measures, such as widening buffer zones or further reducing the 5G signal, similar to what other countries have done,” Black said. In other words, many of the planes used by regional airlines may not be allowed to land at some airports in bad weather.
This has already happened at Paine Field, a small airport north of Seattle, Washington. On Monday, all take-off or landing flights at the airport were canceled due to fog. The planes landing at PAE are Embraer 175s, according to The Seattle Timesand the altimeter in those planes is only cleared if it is a certain distance from C-Band towers.
While altimeters can be replaced, Anderson says it’s not as simple as upgrading a part in your computer or adding a gadget to your home. “In general, a radar altimeter could be certified for use on an airplane, but that’s not the end of that journey. It must also be approved for installation on a particular aircraft and shown to work correctly with the other systems on the aircraft.” In other words, he said, you can’t drop a known good-model altimeter on an airplane and get permission right away.
The underperforming altimeters can be modified to work by changing the frequency or adding shielding, but even then they still need to be recertified. “Certifying any type you’re talking about with the FAA, it’s not trivial. It usually takes a lot of time,” Anderson told me. “They don’t like to rush things, especially after the 737 MAX.” And of course there’s the biggest question, which is relevant in each of the situations, “who is going pay for it?”
The RAA argues it’s wrong for airlines to hook up after spending “millions on these altimeters, which are advanced technology specifically designed to allow safe use in weather conditions,” Black said. “These altimeters met and exceeded regulatory standards, but investment could be completely undermined by 5G signal interference at many, many airports.”
As for what to do with the 5G rollout and its impact on flights, Black repeatedly called for telecom and aviation companies to work together to ensure that C-Band could be rolled out without causing more problems with the FAA. “It seems to me that two sectors – telecom and aviation – are on the same side as our common goal is to resolve this in a mutually acceptable way so that we can do good for our respective customers, of whom we are likely to share a lot,” she said. Black also cited other countries with the rollout of 5G C-Band and said there was “full industry collaboration so that solutions were workable for everyone. I think that’s improving, and it needs to keep improving.”
There’s something of a deadline for when things need to get right. As wireless spectrum consultant Tim Farrar points out, AT&T and Verizon have said they will stop creating special buffer zones in July “unless there is credible evidence that real-world interference would occur if measures were relaxed.” Based on the FAA’s July 19 statement, which states that the “new security buffer announced Tuesday” […] further expanding the number of available airports for aircraft with previously approved altimeters to perform low-visibility landings”, it is possible that the permissions it is now getting are only good with those 5G-free areas (and this seems to be especially the case for the regional aircraft that have restrictions based on distance from C-Band towers).
farrar tweeted that “it is becoming increasingly clear that there is no way to lift implementation restrictions in July”, which could lead to a recurrence of this situation in just a few months. Ostrower, for his part, seems to think the FAA will be under a lot of pressure to be prepared for the July deadline. “You know, look, the FAA has been rattling on about these and many other things in recent years,” he told me, saying that the “hue and scream from passengers and airlines will definitely push them into action.”