Mobile phones have become an integral part of modern existence, making it possible for us to call or text other people from anywhere. Or rather, from almost anywhere. One of the places where federal regulations bar you from using your phone — or rather, its capability to connect to a phone company's cellular network for voice and data — is while you're flying on a U.S. airliner.
Using a phone on to connect to a cellular network while on an airline flight actually is prohibited by not just one but two different parts of the U.S. government.
The Federal Aviation Administration (FAA) has long prohibited the use of phones and other devices to connect with cellular networks, because of what it says is the potential for those electronic gadgets to interfere with aircraft navigation and communication systems. In 2013, the FAA did soften that stance slightly, allowing the use of mobile devices in airplane mode, in which the phone's ability to transmit radio signals to cell towers is turned off, as long as airlines could show that it wouldn't interfere with a plane's electronics. (In airplane mode, the ability to call and text is turned off. WiFi and Bluetooth access are also turned off but you can turn them on separately while still remaining in airplane mode.)
Additionally, the Federal Communications Commission (FCC), which regulates mobile phones, banned airline passengers in 1991 from making calls in flight, out of concern that those signals would interfere with communications networks on the ground. That prohibition is still in force, though in recent years the FCC considered — but then rejected in November 2020 — a proposal to allow a technology that would have permitted passengers to make cellular calls without creating interference. (More on why later.)
So, is it really necessary to ban cellphone use on airline flights? Researchers in the mid-2000s concluded that phones did have the potential to interfere with critical electronics in aircraft, though they couldn't find any instances in which it had caused an accident, as this 2006 IEEE Spectrum article details.
Sven Bilén, a professor of engineering design, electrical engineering, and aerospace engineering at Penn State University, says that phones aren't as much of a safety issue as they once might have been.
"Most planes nowadays are hardened," explains Bilén, who wrote an article about cellphones on aircraft for The Conversation in 2018. "There's always the possibility of some adverse interaction, but it's essentially a risk that the companies have tried to mitigate by hardening their electronics, by putting shielding around them." Shielding or hardening means to surround the airplane's electronics (like the flight control systems) with an electrically conductive material to prevent electromagnetic interference from computers and cellphones.
There's pretty good evidence that such protection works, because as Bilén notes, there probably are plenty of passengers who don't turn off their phones' cellular connections, sometimes unintentionally, even after flight attendants remind them before takeoff.
"If there were major problems, we'd see planes falling out of the sky," Bilén says.
But that doesn't mean you can just ignore the ban.
Cellphones and Ground Networks
"We are not aware of any technology that enables airline crews to identify someone who may be trying to make an in-flight call with a cellular phone," an FAA representative explains via email. That said, if you try to make a call, you're likely to get caught, because "cabin crews or other passengers likely would be able to see whether a passenger is talking on a phone while a plane is airborne," the representative added.
The potential of cellphones to interfere with ground networks is probably more of a potential problem these days, according to Bilén. A bunch of people making calls while moving rapidly through the air theoretically could be pinging cell towers all over the places, taxing their ability to process and hand off the calls to the next cell in the network.
In practice, at normal cruising altitude of 36,000 feet (11 kilometers) "if you do have your cell connection on in the air, you probably won't get any cell towers," Bilén says. "The cell towers don't expect there to be traffic in the air, so their radiation patterns are focused on the ground." It's probably only when planes descend to less than 10,000 feet (3 kilometers), as they get closer to landing, that passengers could flip on their phones, connect and cause interference.
So, how is it that some planes offer cellphone service on board? There's a technology that allows passengers to make calls without the risk of interfering with the plane's electronics or ground networks. As Bilén details in his article, picocells — basically, a miniature, low-power cell tower installed on the plane — allow calls to be transmitted over the aircraft's internet connection. Since the early 2010s, Virgin Atlantic, a British airline, has provided in-flight mobile service using that technology. But the service is discontinued once an aircraft is within 250 miles (402 kilometers) of the U.S. border.
Even though it's technologically feasible, don't expect to be able to make cellphone calls on a U.S. airline flight anytime soon. The FCC spent seven years considering a rule change that would have allowed cellphone service on flights, but ultimately abandoned the idea, after it faced intense opposition from a wide range of groups, ranging from flight attendants and machinists and aerospace workers to federal law enforcement officers. As this 2014 comment details, one concern was that phones might be used by terrorists to detonate explosive devices. Another criticism was that if passengers had phones pressed to their ears, they might not hear important safety instructions from flight attendants.
Others objected because they saw passengers talking on phones as an annoyance inside the cramped confines of an airliner. "The last thing any of us need during a flight is to be treated to the loud conversations of others while we're trying to read/sleep/converse quietly with a companion," one commenter wrote.
Bilén, who says he uses plane flights to go through his emails and respond to them, agrees with that view. "The whole idea of someone yapping next to you — that would drive me nuts," he says.