Admit it. You know you're not supposed to use your cell phone on airplanes, but while the plane approaches lift-off and the flight attendants look the other way, you've been known to pull out your phone or BlackBerry to send off a furtive message or sneak in one last hushed call.
Or, even if you're not so bold, haven't you ever disembarked from a plane only to realize that you simply forgot to the turn the pesky thing off?
Every so often, we hear about the chaos or delay caused by the passenger who failed to switch off his cell phone, iPod or Nintendo DS. But, despite the millions of gadgets that take to the skies each year, not one accident has been conclusively attributed to interference from an electronic device.
So, why then, is the use of cell phones on planes still taboo?
Though there are technical issues at play, experts suggest the real reason has more to do with perceived public opinion than hard science.
And, as more and more foreign carriers outfit their planes with technology that enables air-to-ground communication, aviation experts say it might not be long before Americans too get the go-ahead to make phone calls from 40,000 feet up.
A Concern, Not Necessarily a Fact
"It's a concern rather than a fact that phones could radiate energy which in turn could cause interference with aeronautical systems," said David Russell, COO of OnAir, a Swiss company that provides several European, Middle Eastern and Asian airlines with air-to-ground communication systems.
Like the United States, several European countries have banned cell phones on airplanes. But, Russell said, as safety and ground telecommunications issues have been addressed by new technology, those bans have been lifted.
In April 2008, Air France became the first airline to give a trial run to a service that let passengers use their own phones to e-mail, text and make and receive phone calls. Oman Air, Royal Jordanian and Shenzhen Airlines have announced similar partnerships with OnAir.
But though in-flight mobile phone systems have been popping up around the world, U.S. regulators have been a harder nut to crack.
Simple Approach Doesn't Guarantee Safety
As most travelers know, once the cabin door closes, all MP3 players, electronic games, pagers, DVD players and other electronic devices must be turned off until the plane reaches 10,000 feet. The use of cell phones is prohibited anytime the plane is in the air.
For the Federal Aviation Administration, safety is the highest concern. Portable electronic devices, including cell phones, emit radio signals that officials worry will interfere with aircraft communications or flight control, navigational and other on-board electronic equipment.
Since 2003, the RTCA (for Radio Technical Commission for Aeronautics), a non-profit FAA advisory group, has been examining electromagnetic interference from electronic devices.
And though it acknowledges that virtually all of the reported evidence for banning electronics below 10,000 feet and cell phones during the entire flight is anecdotal, it still maintains that caution is key.
Dave Carson, a Boeing official and co-chair of the RTCA committee charged with researching electronic devices on airplanes, told ABCNews.com that part of the difficulty in addressing the issue has to do with the differences between the world of consumer electronics and the world of avionics.
The consumer electronics industry is "such a dynamic industry, where technology evolves seemingly daily," but the aviation industry is "where things progress very cautiously," he said. "Where those two technology worlds come together is the potential for problems."
It's difficult for avionics experts to keep up with the fast-moving consumer electronics industry and test all of the newest gadgets.
But Carson said his committee, which comprises regulators, airline representatives and academics, has been looking at the technology behind the devices to test how different classes of consumer devices could interfere with aircraft equipment.
Although consumer electronics, such as cell phones, are supposed to operate within bands of the electromagnetic spectrum away from aviation bands, Carson said technology doesn't always behave the way it's supposed to.
"Spurious emissions," for example, he said, could interfere with crucial on-board navigational and communications systems. But, he said, during a flight, even smaller disturbances -- such as smoke alarms activating because of cell phone interference -- could have more serious consequences.
"The simplistic approach doesn't get you the safety the American public deserves," he said.
But, both the FAA and the Federal Communications Commission oversee the use of cell phones on airplanes. And contrary to what most passengers think, it's the FCC – not the FAA – that implemented the cell phone ban in the first place.
Safety Not the Only Issue
It's true that before an airline could allow cell phone use in-flight, it would have to prove to the FAA that it wouldn't interfere with the airplane systems. But the FAA says the point is moot.
"As far as the wireless system goes, the final authority rests with the FCC," Les Dorr, an FAA spokesman told ABCNews.com.
Since 1991, the FCC has banned the use of cell phones on airplanes because of potential interference with ground networks.
When you use your cell phone in Times Square, for example, the phone searches for the closest cell towers and, assuming you're in a place with good coverage, it doesn't have to work too hard to complete a call.
But, when you use your phone on an airplane, thousands of feet above the cell towers and moving 500 miles per hour, the phone and the network, essentially, get confused. Too many cell towers and too many channels are available to a single phone at a given time.
In addition to opening up the possibility for interrupted calls and other problems on the ground, the phone emits a stronger signal that both drains the battery and increases the possibility of interference with on-board equipment.
Technology like OnAir's uses a picocell to try to re-create a ground situation in air. The picocell acts like a mini cell tower that enables phones on the plane and towers on the ground to interact normally.
But despite technology that could address this outstanding network issue, the FCC stands by its ban.
"Certainly with advances in technology, it's something that the FCC may reconsider," Rob Kenny, an FCC spokesman told ABCNews.com. "But first and foremost, we need to find ways to negate harmful interference to airplanes' navigation and communications systems."
Additionally, he said, that when the FCC proposed lifting the ban in December 2004, it was flooded with thousands of comments from individuals, companies and associations in favor of the ban.
(In April 2007, the FCC ultimately dropped the inquiry into lifting the ban, saying it was "premature" to decide because they didn't have enough technical information about interference issues.)
"The majority of people would not want to see cell phones on planes," Kenny said.
To his point, as more and more revenue-hungry U.S. airlines, such as Delta and American, offer in-flight wireless communications, passengers are responding with mixed emotions.
Connectedness vs. Calm
While they appreciate the opportunity to stay in touch with personal and professional contacts on the ground, they are also reluctant to sacrifice calm for connectedness.
Both Delta and American use Aircell's in-flight Internet service to turn their aircraft into flying Wi-Fi hotspots. But though Aircell is capable of enabling voice services, it says consumer preference is as much of a hurdle right now as the cell phone ban.
"The airline and the passengers themselves say they don't want that service," Joe Cruz, Aircell's chief technology officer, told ABCNews.com. "They want peace and quiet when they're flying."
And, as for the safety issue, he said that although safety is a concern, it isn't a known fact that cell phones have negative effects on navigation systems.
Rick Seaney, CEO of FareCompare.com and ABCNews.com airline industry columnist, agreed that hard evidence backing up the ban is scarce.
"It's a myth," Seaney said. "It's a suggestion more than an edict. ... I think it's a fear of the unknown."
Still, he continued, customers don't necessarily want "yellular" service on airplanes and all the noise they expect it to bring. But, even so, if the airlines see green, it could get the green light.
"People hate it, but it's money for the airlines," he said. "The bottom line is it's going to be on airlines in the next four to five years."