The holiday season is here, and for many of us, this means flying across the country to see family or–if we’re lucky–across the world to escape the winter. In either case, boarding a plane in the US means being greeted with the familiar instruction to turn portable electronic devices onto airplane mode or turn them off entirely.
The reason for this policy has long been that cell phones might interfere with aircraft systems. But the EU lifted its long-standing ban on cell phone usage in airplanes in 2022–so why are Americans still required to use airplane mode?
Richard Levy, an aviation consultant who worked for decades as a pilot for American Airlines and is now an instructor for Southwest Airlines, says that the FAA’s official line remains that cell phone signals could interfere with aircraft communications and navigation equipment. (The FAA, for its part, simply referred Popular Science to the regulations that require passengers to follow all crew members’ safety instructions, and did not comment further.)
The word “could” is obviously doing a lot of work in that sentence; what is the actual risk? Levy says that in modern aircraft, at least, the risk of interference with navigation equipment is minimal. “In the latest Boeings and Airbus planes,” he explains, “the navigation equipment [relies] on GPS, the same as in cars. And I’m not going to say the odds [of cell phones interfering with that system] are zero, but they’re next to zero.”
As far as communications equipment goes, it’s instructive to look at the FAA’s guidance on the issue, which is contained in Advisory Circular 91.21-1D on the subject of “Use of Portable Electronic Devices Aboard Aircraft.” This document gives some insight into the FAA’s thinking on the issue—especially the “History” section, which explains that the ban “was established in May 1961 to prohibit the operation of frequency modulation (FM) receivers since they were determined to interfere with the operation of aircraft navigation and communication systems.”
This, at least, makes perfect sense, because aircraft communication frequencies and FM radio broadcasts both use a very similar part of the VHF area of the electromagnetic spectrum. In most parts of the world (including the USA), FM radio uses frequencies between 87.5 MHz and 108 MHz, while aircraft communication frequencies start at around 120 MHz. It’s absolutely feasible, then, that someone trying to listen to a transistor radio in the cabin could cause problems.
Cell phones, however, use much higher frequencies than FM radios. The lowest-frequency cellular band bottoms out at 698 MhZ, and modern 4G and 5G networks mostly use frequencies in the GHz range. It seems extremely unlikely, then, that cell phones could cause problems or air communications. The FAA itself has already commissioned two studies—one in 2006 and one in 2012—that found no evidence that cell phone signals interfere with aircraft systems.
Nevertheless, there are anecdotes about phones interfering with communications equipment. Earlier this year, a pilot described on TikTok how he had experienced interference in wired headset, which he said felt like “a mosquito” in his ear. “If you have an aircraft with 70, 80, 150 people on board,” he said, “and even three or four people’s phones start to try to make a connection to a radio tower for an incoming phone call, it sends out radio waves. There’s the potential that those radio waves can interfere with the radio waves of the headset that the pilots are using.”
What does Levy make of this? “Prove to me,” he says, “that [the pilot] knows it was a cell phone [causing the interference]. It could be all kinds of stuff causing the static. I’m very skeptical.”
So why is the US so reluctant to lift the ban? Several commentators have theorized about the “real” reasons for US authorities’ intransigence on this issue, reasons that have less to do with science and more to do with pragmatism: Gizmodo, for example, hypothesized earlier this year that the continuing ban on cell phone usage is “completely about air rage.” (This idea is supported by the 2012 FAA study, which called for public comment on this issue—79 of the 148 comments received opposed lifting the ban, and “the dominant concern expressed by these comments was that voice conversations by passengers using their cell phones would result in annoyance and distraction to other passengers.”)
Does Levy lend any credence to such ideas? “I do,” he says. “You and I have been at a grocery store, and somebody is talking way too loud. They don’t mean harm—but talk quietly, or go to your car, or go to a park.” On a plane, of course, there’s no such escape, and the idea of being stuck for hours in the middle seat between two people talking loudly about their start-up ideas sounds like an entirely fresh circle of hell.
Levy also suggests that authorities could see inattention as a problem: “Another reason they don’t want people using cell phones on the ground is that [they] want passengers to pay attention to the flight safety briefing.” For what it’s worth, he has less time for this argument: “The Europeans have safety briefings also, and people pay attention [to those].”
So what are the chances of the ban being lifted? Levy says that passengers shouldn’t hold their breath. The prohibition on cell phone usage isn’t left to the discretion of airlines; it’s enshrined in two separate Titles of the Code of Federal Regulations (specifically Title 14, which covers Aeronautics and Space, and Title 47, which covers telecommunications.) The former is issued by the FAA and the latter by the FCC, meaning that two federal agencies would have to decide to change their respective stances on the issue.
The FAA and FCC aren’t the only powerful organizations opposed to any change in the policy; Levy suggests that unions may also be happy for things to remain as they are. In the commercial air industry, he says, “unions [still] have a lot of authority. I don’t know if the airline employee unions are petitioning the FAA to [retain the ban”, but if so, they have a lot of lobbying power.”
However, he says, ultimately the issue is that “the US is very conservative in this way. My guess is that they’re waiting for data somehow to prove [definitively] that there’s no risk.”
This story is part of Popular Science’s Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall.Have something you’ve always wanted to know? Ask us.
