Why is there a ban in the first place?
The airline industry and the Federal Aviation Administration worry that electromagnetic waves emitted by passengers' personal electronic devices — including MP3 players, laptops, tablets, and cellphones — could interfere with an aircraft's electronic controls, or avionics. Commercial pilots file dozens of reports every year detailing how their radios, GPS navigation systems, and collision-avoidance boxes suddenly went haywire, but began functioning again when passengers were asked to check that all their devices were turned off. That kind of circumstantial evidence led the FAA in 1993 to urge that laptops, audio players, and other electronic distractions not be used during takeoff and landing. Once an aircraft is above 10,000 feet, aviation officials say, a flight crew would have enough time and altitude to safely react to any electronic problem. The risk in allowing passengers to use their electronics at lower altitudes is tiny, said Boeing engineer David Carson, but since a freak occurrence could end in disaster, "why take that risk?" 

Is there any evidence to support this fear?
It's mostly theoretical. Any electrical device can generate interference as electricity flows through its wiring. Even those without wireless signals, like portable CD players, can emit potentially troublesome electromagnetic radiation. Devices that intentionally transmit radio waves, like cellphones, pose even greater problems. Some engineers think that such emissions could potentially drown out weak signals from radio navigation beacons on the ground or GPS satellites in space. Wireless industry spokesman Michael Altschul says such fears are baseless, since separate radio frequencies are assigned for aviation and commercial use. "Plus," he said, "the wiring and instruments for aircraft are shielded to protect them from interference from commercial wireless devices." In two decades of tests, government scientists and experts at Boeing and Airbus have bombarded planes with electromagnetic radiation, but have never succeeded in replicating the problems reported by pilots, or confirmed that electronic devices caused any equipment failure.

Do some fliers ignore the ban?
A recent survey found that 40 percent of air passengers didn't bother to turn their phones off during takeoff or landing; 7 percent left their devices' Wi-Fi and cellular communications functions active, and 2 percent surreptitiously used their phones to talk or text onboard. University of Illinois psychologist Daniel Simons estimates the odds of all 78 passengers on an average-size U.S. domestic flight powering down their phones completely as "infinitesimal: less than one in 100 quadrillion." If personal electronics were as dangerous as the FAA rules suggest, "navigation and communication would be disrupted every day on domestic flights," he said. "But we don't see that." In addition, flight crews now freely use iPads in the cockpit instead of bulky paper operating manuals. And above 10,000 feet, many U.S. airlines happily allow passengers to use the Internet via onboard Wi-Fi systems for a fee, with no reports of dangerous interference with airplane avionics.

Will the FAA ever ease up its rules?
It's considering doing just that. As more and more people replace books and magazines with Kindles, iPads, and smartphones, pressure is growing to lift the ban. The FAA announced last year that it would conduct a thorough review of its electronic device policy — but didn't say when that review would be completed. Sen. Claire McCaskill (D–Mo.) has warned the FAA that if it doesn't soon relax its rules on e-readers and other portable electronics, she will introduce legislation forcing it to do so. "I'm big on getting rid of regulations that make no sense," she said, "and I think this is one."

When might the ban end?
Conceivably, within a year, although bureaucracies can move very slowly. Current guidelines require each airline to test every make and model of each electronic device it wants the FAA to approve for each type of aircraft in its fleet. But the FAA is now seeking to bring together airlines, aircraft manufacturers, technology firms, and the Federal Communications Commission to streamline the certification process for tablets, e-readers, and other gadgets, so entire classes of devices could be approved at one time. The ban on using cellphones to make calls or send texts in the air, however, is likely to remain for the foreseeable future.

Why single out cellphones?
The trouble there is possible interference with cellular networks, not with aircraft avionics. Cell networks operate on the principle that a cellphone is only within range of one or two cellular towers. A phone that's moving at 500 mph at 30,000 feet, however, can shower signals on any number of masts, confusing the network's software and potentially leading to dropped calls between land-based customers. Besides, surveys show that most passengers dread the thought of some jerk in the next seat being free to conduct annoying cellphone conversations from New York to Los Angeles. "An aircraft is one of the few places left on earth where you can actually escape from mobile phones," said aviation and travel writer Benét Wilson. "I hope it stays that way."

Sky-high punishments
Many passengers ignore the electronics ban in flight, but those who get caught — and remain defiant — can pay a serious price. Actor Alec Baldwin was booted from an American Airlines flight in 2011 after he ignored a flight attendant's repeated requests that he stop playing a game on his smartphone. Last November, half a dozen police cars raced onto the tarmac and surrounded a plane at New York's La Guardia Airport as if there were a terrorist onboard. They were there to arrest a 30-year-old passenger who had refused to turn off his phone during taxiing. Scofflaws on foreign flights can risk more than ejection. In 1999, oil worker Neil Whitehouse refused to switch off and hand over his phone to a British Airways flight attendant, earning a year in jail. A Saudi Arabian passenger who flouted the cellphone ban two years later received an even harsher punishment: 70 lashes.