WASHINGTON -- The regional airliner was climbing past 9,000 feet when its compasses went haywire, leading pilots several miles off course until a flight attendant persuaded a passenger in row 9 to switch off an iPhone.
"The timing of the cellphone being turned off coincided with the moment where our heading problem was solved," the unidentified co-pilot told NASA's Aviation Safety Reporting System about the 2011 incident. The plane landed safely.
Public figures from Sen. Claire McCaskill to actor Alec Baldwin have bristled at what they say are excessive rules restricting use of tablets, smartphones, laptops and other devices during flights.
More than a decade of pilot reports and scientific studies tell a different story. Government and airline reporting systems have logged dozens of cases in which passenger electronics were suspected of interfering with navigation, radios and other aviation equipment.
The FAA in January appointed an advisory committee from the airline and technology industries to recommend whether or how to broaden electronics use in planes. The agency will consider the committee's recommendations, which are expected in July, it said in a statement.
Laboratory tests have shown some devices broadcast radio waves powerful enough to interfere with airline equipment, according to NASA, aircraft manufacturer Boeing and Britain's Civil Aviation Authority.
Even Delta Air Lines, which argued for relaxed rules, told the U.S. Federal Aviation Administration its pilots and mechanics reported 27 suspected incidents of passenger electronics causing aircraft malfunctions from 2010 to 2012. Atlanta-based Delta said it couldn't verify there was interference in any of those cases.
The airline industry has been divided. Delta said in its filing that it welcomes more electronics use because that's what its passengers wanted. United Continental Holdings said it preferred no changes because they'd be difficult for flight attendants to enforce.
CTIA-The Wireless Association, a Washington trade group representing mobile companies, and Amazon.com, the Seattle online retailer that sells the Kindle e-reader, urged the U.S. FAA last year to allow wider use of devices. Personal electronics don't cause interference, CTIA said in a blog post last year.
Passengers' use of technology and wireless services "is growing by leaps and bounds" and should be expanded as long as it is safe, the Consumer Electronics Association, an Arlington, Va.-based trade group, said in its filing to the FAA last year.
Federal Communications Commission Chairman Julius Genachowski agreed in a Dec. 6 letter to the FAA.
Broader use of on-board electronics would help providers of approved aircraft Wi-Fi services by letting passengers use them longer. Gogo, based in Itasca, Ill., says it has 82 percent of that market in North America, and Qualcomm on May 9 won permission from the FCC to proceed with a planned air- to-ground broadband service for Wi-Fi equipped planes.
The FAA prohibits use of electronics while a plane is below 10,000 feet, with the exception of portable recording devices, hearing aids, heart pacemakers and electric shavers.
Once a flight gets above that altitude, devices can be used in "airplane mode," which blocks their ability to broadcast radio signals, according to the FAA. There's an exception for devices that aircraft manufacturers or an airline demonstrates are safe, such as laptops that connect to approved Wi-Fi networks.
The potential risks from personal electronic devices are increasing as the U.S. aviation system transitions to satellite- based navigation, according to the FAA. In order to improve efficiency, planes will fly closer together using GPS technology.
As a result, interference from electronics "cannot be tolerated," the agency said last year.
While sticking with its prohibitions on use during some phases of flight, the FAA starting in 2010 issued guidelines allowing broader use of personal electronics.
Following techniques suggested by RTCA, a Washington- based non-profit that advises the FAA on technology, airlines have been able to install Wi-Fi networks allowing passengers to browse the Web in flight.
Four in 10 airline passengers surveyed in December by groups including the CEA said they want to be able to use electronic devices in all phases of flight. Thirty percent of passengers in that same study said they'd accidentally left on a device during a flight.
McCaskill, D-Mo., has called for lifting restrictions on non-phone devices such as the Kindle. In an interview, she called the existing rules "ridiculous."
"I was aware from the research that's been done that there has never been an incident of a plane having problems because of someone having a device on in the cabin," she said.
The dangers from radio waves interfering with electronic equipment has been known for decades. A fire aboard the aircraft carrier USS Forrestal in 1967 killed 134 people, when a rocket on a fighter jet accidentally fired after a radar beam triggered an electronic malfunction, according to a 1995 NASA review.
Restrictions on U.S. commercial aircraft began in 1966 after research found some portable radios interfered with navigation equipment, according to the FAA's request last year for comments on whether it should change existing rules.
In one 2004 test, a now-discontinued Samsung Electronics wireless phone model's signal was powerful enough to blot out global-positioning satellites, according to NASA. The device, which met all government standards, was tested because a corporate flight department had discovered the phone rendered a plane's three GPS receivers useless, NASA's researchers reported.
While such incidents are rare and difficult to re-create afterward, they continue to pile up. A log kept by the Montreal- based International Air Transport Association airline trade group recorded 75 cases of suspected interference from 2003 to 2009, Perry Flint, a spokesman for the group, said in an interview.
Peter Bernard Ladkin, a professor of computer networks at the University of Bielefeld in Germany, compiled similar accounts from pilots in Europe, he said in an interview.
"These are serious, conscientious pilots," Ladkin said. "They know what they're doing. They don't subscribe to theories about ghosts or something."
Damaged devices have transmitted on frequencies they weren't designed for, according to David Carson, an associate technical fellow at Boeing who has participated in industry evaluations of electronics.
If those radio waves reach an antenna used for navigation, communication or some other purpose, it may distort the signal it's supposed to receive.
Inflight Wi-Fi systems are safe in part because devices connect to them at low power levels, according to Carson, who was co-chairman of an RTCA panel that produced testing standards.
Devices searching for a faraway connection, such as a mobile phone trying to connect to a ground network in flight, send out more powerful radio waves, he said.
Airlines such as Delta and Alaska Air Group have used the FAA guidelines to allow their pilots to carry Apple iPads to replace paper charts and manuals. McCaskill and others have used that as an example of why passengers should be allowed to use tablet computers during landing and takeoff.
One difference is that airlines don't purchase tablet models that use connections through wireless phone networks. Similar devices used by passengers haven't been tested for safety in the passenger compartment, Carson said. Plus, there's no guarantee passengers will put the devices into airplane mode or the devices haven't been damaged, he said.
"Something a passenger brings in, you don't know if it fell in a mud puddle or they put a bigger battery in," he said.
The RTCA group recommended against allowing passengers to use devices during taxi, landing and takeoff, Carson said.
The Association of Flight Attendants, the U.S.'s largest union for those workers, told the FAA last year that electronic devices should be stowed during those critical phases of flight, just as bags and purses must be.
Any decision should be based on science, not on politics or passengers' desires to stay connected, John Cox, a former airline pilot who is chief executive officer of the Washington- based consulting firm, Safety Operating Systems, said in an interview.
"The question is: Do we want to do aviation safety based on lack of testing and certification standards?" Cox said.