The doors close, the flight attendant points out the emergency exits, and the familiar “please switch your devices to airplane mode” travels through the cabin. Your hand reaches for the little airplane icon on its own—it’s a ritual polished by decades of repetition, and nobody has asked “why?” in a long time. Yet the answer is one of the neatest stories about how bureaucracy is born and refuses to die. Airplane mode is not one rule at all, but two bans issued by two different agencies, at different times and for different reasons. One agency feared for navigation; the other feared for cell towers. The airplane has nothing to do with it: physics was informed long ago that its opinion would not be taken into account, and it made peace with that.
The first to take on onboard electronics was the US Federal Aviation Administration. Studies in 1958–1961 showed that portable FM radios interfered with navigation and communications. The complaint was purely physical, and a fair one: FM broadcasting and aviation communications occupy neighboring stretches of the spectrum—broadcasting takes up 87.5–108 MHz, while aviation communications begin at roughly 120 MHz. A person with a transistor radio in the cabin was, in that era, a walking source of interference—and in May 1961 the FAA banned FM radios. In 1966, the agency codified the requirements in 14 CFR 91.19—which over time spread to all portable electronics. An amusing detail: in Advisory Circular 91.21-1D on portable electronics, the FAA itself described the ban’s lineage with the phrase, “the prohibition was established in May 1961 to prohibit FM receivers.”
The FAA left it to airlines themselves to decide which devices could be used in flight: the industry worked out the requirements for a “safe device,” and procedures for testing portable electronics were set down in RTCA standards, which also underpinned FAA-commissioned research. An unexpected detail: there were 2 such studies, in 2006 and 2012, and neither found evidence that cell-phone signals interfere with onboard systems.
Cell phones fell under a separate ban, imposed by an entirely different agency. On December 12, 1991, the US Federal Communications Commission prohibited the use of cellular service in the air. The commission’s ruling says outright what it feared: not the autopilot, but ground networks. A phone on the ground sees the nearest tower—because buildings and obstacles weaken the signal, and it simply cannot reach distant towers. From several kilometers up, there are no obstacles; the signal reaches many base stations at once, and the network cannot tell which cell to assign the subscriber to. The principle of frequency reuse, on which the entire capacity of cellular networks rests, would start to crack: an airborne signal lights up the same frequencies across different segments of the network, and interference can affect even networks in neighboring regions.
The physics are simple: a phone bouncing between towers at 800 km/h keeps losing stations and searching for new ones, knocking on distant towers’ doors at higher power. The call is useless, the battery drains before your eyes, and the network on the ground puts up with interference. That is exactly what the FCC built its ban around, and flight safety does not appear anywhere in its reasoning.
If the bans are not about the airplane, then what was actually measured, and what are the passenger myths still lying about?
The most dangerous scenario goes like this: a passenger forgets about their phone, and the autopilot goes insane. There really are stories like that: in 2011, ABC News reported on a confidential IATA report—between 2003 and 2009, 125 airlines reported 75 cases in which crews suspected interference from passengers’ electronics. Phones appeared in roughly 4 cases out of 10. In one of them, the autopilot disengaged at an altitude of around 4,500 feet. So crews had their suspicions, but there was no hard evidence—the kind you can hold in your hands—behind them.
In 2003, researcher Bill Strauss and his colleagues checked what was actually happening onboard. His measurements became the basis of a Carnegie Mellon University study for the FAA: on 37 scheduled flights, he monitored the radio spectrum in the cabin and detected 8 calls. 2 of them began at an altitude of 35,000 feet—even though phone manufacturers at the time insisted that there was no reception at that altitude. What is more, in roughly a third of cases, instruments detected emissions in the GPS band, sometimes immediately after a phone signal. Strauss called the result “half alarming”: he did not urge a permanent ban on phones, but believed that onboard spectrum monitoring and coordinated rules from the FAA, FCC, and the industry were needed. The irony was that the spectrum readings showed phones worked in cabins regardless of bans, while regulators were still debating what the rule should look like.
In 2006, MythBusters took up the subject. In a lab, they blasted an unshielded navigation instrument with a generator simulating a phone signal: at frequencies of 800–900 MHz, the instrument really did malfunction. They repeated the experiment in an actual airplane on the ground—and not a single signal affected its electronics. The difference was explained by shielding: onboard electronics are protected from this kind of interference, while the lab instrument was not. The MythBusters also debunked the conspiracy theory that the ban had been invented to sell expensive onboard phones.
That leaves the buzz. The distinctive “bzz-z-z” in your headphones a second before a call—that is a real physical effect, and pilots who heard it for years cannot and should not argue with it. A GSM signal is intermittent by nature, and its harmonics crept into the audio path. But the buzz is interference in the headphones, not in the autopilot: people complained about the cockpit audio system for exactly that reason for years. The classic buzz, though, is specifically tied to GSM, and second-generation networks are gradually being shut down in many countries. No public measurements could be found showing how much quieter cockpits became with the move to 4G and 5G.
On October 31, 2013, the FAA softened its part of the rule: a committee of 28 airline, manufacturer, pilot, and flight-attendant representatives (PED ARC—Portable Electronic Devices Aviation Rulemaking Committee) concluded that most passenger aircraft could withstand emissions from ordinary electronics. Tablets and e-readers were allowed at every stage of flight—including takeoff and landing; the device had to be in airplane mode, with Wi-Fi and Bluetooth switched off. The prohibited list at the time included wireless headphones, pagers, two-way radios, and satellite phones.
Europe went further. In December 2013, following the FAA, the European Aviation Safety Agency allowed electronics in airplane mode to be used during every stage of flight. At the end of September 2014, EASA allowed airlines to let passengers skip airplane mode altogether—provided the airline tested its aircraft and proved that nothing threatened them.
Only the FCC’s 1991 ban survives to this day. At the end of 2013, the FCC proposed lifting it too, but in 2017 the commission’s new chairman, Ajit Pai, called the idea “ill-conceived,” and in November 2020 it was finally shelved. And this is where the most interesting thing comes out: official regulators, it seems, never really wanted to legalize cabin calls. Pilots and flight attendants had opposed them for years, and the FCC specifically mentioned their sharp objections when it declined to lift the ban. Nobody wants to sit beside someone talking on the phone for 10 hours straight. Airplane mode turned out to protect more than networks—it is also regulator-enforced quiet in the cabin.
Incidentally, the switch itself is older than all these battles: the Nokia 9210 Communicator of the early 2000s already had a “Flight” profile—it blocked communications but still let you read downloaded email and write notes.
European regulators described how to provide cellular service directly onboard as early as 2006, and airlines have been using it since 2008. A small base station—a picocell—is installed in the cabin. Passengers’ phones connect to it at minimal power, because the station is only a few meters away. Calls and data go to the ground via satellite, and to keep phones from latching onto ground towers, the aircraft may carry a separate unit that jams all mobile frequencies except the picocell’s frequencies. Below 3,000 meters, the system is switched off. It is an architecturally clean solution: the aircraft itself becomes a cell, frequency reuse is not disrupted, and ground networks do not suffer.
The final act is recent. US operators launched 5G in the 3.7–3.98 GHz band, next door to 4.2–4.4 GHz, where aircraft radio altimeters operate. In January 2022, the FAA introduced protective zones around dozens of airports, and airlines had to cancel flights. The altimeters were later replaced or fitted with filters, with the deadline set for February 2024. The danger came from powerful ground transmitters—passengers, as usual, had nothing to do with the drama. A genre classic: a new turn in the same spectrum conflict, and once again it is physics that must be regulated, not passenger behavior.
A postscript on why the ritual survived every relaxation. In the United States, the FCC ban is alive, and American airlines have no choice. A European airline does have a choice, but first it has to test its fleet and prove safety—it is easier and cheaper to keep the rule, especially since onboard Wi-Fi works in airplane mode anyway. Plus, it is convenient for the crew when passengers look at the flight attendant rather than their screens during the safety briefing. There is also a formal point people forget: airplane mode does not switch off every transmitter either—many devices let Wi-Fi and Bluetooth be turned on separately, and carriers’ rules vary. In Russia, for instance, S7 Airlines and Ural Airlines ask passengers to put away their phones while taxiing, taking off, and landing; Pobeda requires gadgets to be switched off or put into airplane mode—and the same smartphone follows different rules on different flights.
In the end, airplane mode primarily protects cellular networks on the ground, pilots’ ears, and the nerves of the people in the next seat. The aircraft comes later on that list—largely because it has officially been considered resilient to ordinary electronics since the early 2010s. A legal relic prescribes a ritual that physics approved long ago, regulators partly repealed, and the human factor does not want repealed. And that is perhaps the most honest way to explain why the little airplane icon in a phone’s quick-settings panel is not about flight safety, but about everything else at once.
Each regulator protected its own turf: the FAA—navigation from anything that might misbehave on the airwaves; the FCC—the capacity of ground networks. Aviation safety got almost nothing in this pairing: both bans looked like concern for it, but neither was about it. Two bans fused into a single switch—and the little airplane icon will live in every quick-settings panel for as long as someone in this world needs ground towers, a quiet cabin, and an easy one-gesture instruction.