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.