Can Cell Phones on Planes Be Dangerous?

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Because of restrictions placed on the study's methods by the airlines, Strauss says, he was not able to monitor avionics and cellular frequencies simultaneously, just sequentially. This meant he could see spikes in the cellular frequencies when a phone was being used, then switch to watch corresponding spikes in avionics frequencies. The technique provided strong evidence of correlations between cell-phone use and increased interference at avionics frequencies, he says, but it did not prove causation.

Strauss therefore stresses that their study should not be read as an argument that cell-phone use in airplanes is unsafe, but rather as a caution. "We can't tell conclusively if it's safe or not," he says. Safety determinations, Strauss adds, would depend on what new safeguards airlines put in place.

One such safeguard could be cellular technology itself. The leading candidate for an inflight cell-phone system, the "pico cell" approach, reduces each phone's ability to generate radio frequency interference.

Pico-cell systems use small transmitters that collate all the signals from in-cabin cellular calls and transmit them directly to specialized ground- or satellite-based networks. This means phones can operate at their lowest power setting, reducing the likelihood of radio frequency interference. (Most proposed pico-cell systems include an off switch accessible to flight crews, in case a passenger's phone becomes a disturbance.)

Qualcomm, Airinc, and a few other companies are developing pico-cell transmitters. But the technology isn't mature. In one test in 2004, Qualcomm and American Airlines found that an installed pico-cell system could handle only 100 cellular calls and other wireless connections at once. If a cell phone is denied pico-cell access, it will automatically try to find another tower on the ground -- as it would without the system in place.

Alternately, airline passengers with Wi-Fi-equipped laptops could use voice-over-Internet calling systems, such as Skype, if the FAA approved its use in U.S. airspace and access were available. According to a July 2005 memo documenting a hearing before the U.S. House of Representatives Subcommittee on Aviation, the FAA has approved a Wi-Fi system developed by Verizon and United Airlines for Boeing B-757-200 aircraft. Also, Boeings' Connexion Wi-Fi service is already offered on international flights by Lufthansa and other airlines.

But such systems won't be as attractive to users as their cell phones: airlines are sure to charge for Wi-Fi access, not everyone subscribes to a voice-over-Internet service, and Wi-Fi systems are far more expensive to install than pico cells -- approximately $500,000 per aircraft, as opposed to $100,000 for a pico-cell system.

And there's the social aspect. It remains to be seen whether most travelers want airplanes full of people talking on cell phones. Out of more than 8,000 comments submitted to the FCC since it asked for feedback in December 2004 on lifting the cell-phone ban, an overwhelming number were opposed, according to the FCC. And a USA Today/CNN/Gallup poll recently found that 68 percent of occasional air travelers are against lifting the ban.

The FAA even has a term for the problem: "the Annoying Seatmate issue." But spokesperson Les Dorr says the FAA has no mandate or desire to regulate the social aspects of air travel, and can get involved only if it receives reports of cell-phone use interfering with the cabin crew.

Or, as the RTCA's Carson put it, it seems that many airline passengers would like to be able to use cell phones -- they just don't want anyone else to.