It happens on just about every flight now, say flight attendants. The plane's door closes and it's time to turn off personal electronic devices.
And there's always at least one person who keeps talking, texting, tweeting, playing, watching or emailing—and ignoring stern orders to power down.
On rare occasions, a confrontation erupts, such as actor Alec Baldwin's widely reported removal from an American Airlines plane in December. Although airlines say they don't keep track or won't disclose how many passengers get bounced off planes for refusing to switch off devices, flight attendants say it's now the No. 1 spark for unruly behavior.
"People have become so wedded to these devices, and a lot of people really question whether they need to turn them off," says Southwest Airlines flight attendant Thom McDaniel.
Travelers who "think 'it's no big deal' or 'the rule doesn't apply to me'—those are the hardest," says Kelly Skyles, an American Airlines flight attendant. "Most passenger misconduct cases now deal with noncompliance with electronic devices."
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Airline rules backed by federal laws allow crews to turn a plane back to the gate and toss passengers off flights to prevent disputes in the air.
In most cases, it isn't the initial issue that gets people kicked off planes, whether they've been told to pull up their saggy pants, clean up their language or stop playing "Words With Friends" on their iPhones. Instead, it's the ensuing argument.
Flight attendants at American reported 1,306 incidents of customer misconduct to their union, the Association of Professional Flight Attendants, in 2011, up slightly from 1,248 in 2010. Most didn't escalate into confrontations or get reported to law enforcement. The numbers have been going up for three years, with most of the increase related to electronic devices, flight attendants say.
Ms. Skyles, who is the APFA's safety and security coordinator, attributes attitudes toward electronics to "speed limit" psychology—everyone knows there's a speed limit and yet every driver at one time or another will exceed it.
Lots of passengers are skeptical of the danger of leaving devices on—one call or text message or game isn't going to bring down the plane, they figure. And who hasn't left on their BlackBerry and lived to tell?
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Indeed, there's no firm scientific evidence that having gadgets powered up for takeoff and landing would cause a problem, only that there's the potential for a problem.
The Federal Aviation Administration allows pilots to use iPads and other electronic devices to replace charts and manuals in the cockpit, powered up during takeoff and landing. But the FAA says it can't test all the different gadgets passengers may bring on board. The agency worries a multitude of devices could pose more danger than a single iPad for pilots.
Crews have anecdotally reported numerous issues linked to computers or devices on board, such as erroneous warnings on collision-avoidance systems, heavy static on radio frequencies and false readings on instrument landing systems, according to NASA's Aviation Safety Reporting System, a database to which crews submit voluntary incident reports.
In some instances, crews caught passengers talking on a phone or using a computer when they weren't supposed to. The crews were able to end interference by shutting down the device. Turning it back on recreated the problem, suggesting a possible link. (Even if you are far from the cockpit, you may be sitting near an antenna.) But attempts to duplicate interference with cockpit gear in laboratories failed.
In a study published in 2006, researchers at Carnegie Mellon University who rode 37 airline flights with a radio-frequency measuring device found emissions from cellphones that could interfere with global-positioning satellite systems. And the nonprofit RTCA Inc., which advises the FAA on technical issues, said in a lengthy study in 2008 that emissions from transmitting personal electronic devices, or T-PEDS, could interfere with critical aircraft systems.
Regulators believe there is a chance that electronic emissions from passenger devices could interfere with navigation instruments, and if even the remotest possibility of disaster exists, it's better to turn them off for takeoff and landing.
That rule is backed by a sweeping federal law. Passengers must comply with crew instructions on board commercial airplanes, or face potential fines and jail time. And it involves an often-overlooked safety concern: Passengers must be able to hear flight attendants in an emergency, so no headphones are allowed during takeoff or landing.
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"The problem is taking flight attendants away from their jobs, and they have to be ready for an emergency," says FAA spokeswoman Alison Duquette.
Cellphones are banned during entire flights—not just during takeoff and landing—because they can interfere with ground-based antenna capacity.
The Federal Communications Commission, along with the FAA, bans in-flight use because a phone flying at more than 500 miles per hour, six miles above the ground, connects with lots of cell towers, hogging bandwidth. Connecting at that speed and altitude also takes lots of power from the phone, yielding stronger emissions that could interfere with instruments.
There is a technical solution to the cellphone problem. Small cell antennas on airplanes could link to onboard phones and transmit between the ground and the plane safely. These are similar to the small antennas on airplanes that provide Wi-Fi service.
Several international airlines said they would offer cellular service in-flight; Emirates Airline and Etihad Airways have planes in service equipped for cell connectivity. U.S. passengers complained loudly to the FCC when it considered lifting its ban in 2007—they didn't want to have to listen to calls on airplanes.
Flight attendants say one or two people on almost every flight don't seem to think the device ban applies to them.
"There's a lack of awareness of what the rules are, why the rules are there and what the flight attendant's role is," says Veda Shook, an Alaska Airlines flight attendant and president of the Association of Flight Attendants.
Airlines say they train flight attendants in methods to calm confrontations. They also give pilots and attendants leeway to judge whether a passenger should be removed and put on another flight.
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Last year, Southwest saw tempers flare with summer's scorching temperatures. The company is currently working on a plan to keep cabins cooler during short airport stops.
"If we keep the air cool, hopefully we'll keep tempers and discomfort as cool as possible, as well," says Mr. McDaniel, president of the Transport Workers Union local that represents Southwest flight attendants.