Up in the air over cell-phone EMI

And you thought that when you boarded an airliner, hijackers, bad food, surly passengers, and airborne hazards were all you had to worry about. How about electromagnetic interference (EMI) from cell phones? According to a program segment featured on National Public Radio's "Living on Earth," the Federal Communications Commission may change its rules and allow you to use your cell phone in flight.

Current FCC regulations prohibit the use of cell phones in flight because a phone moving at 500 mph doesn't remain in range of any ground site for more than a minute or two, but rules and regulations don't stop anyone with an exaggerated sense of self-importance from dialing up anyway.

And given our seemingly insatiable demands for entertainment and for squeezing the last drops of efficiency out of the workday, DVD players, handheld games, personal computers, and iPod-like gizmos have become standard wearing apparel for air travelers. All of these devices emit EMI in varying amounts, and their use is currently prohibited during takeoff and landing (but not in flight).

A few years ago, a group of researchers from Carnegie Mellon University assembled a test system consisting of a laptop computer, a wideband antenna, and a portable spectrum analyzer and flew the package on 37 commercial flights. According to the recently published research report, analysis of the RF environment on board showed that among other parts of the EM spectrum, transmissions from cell phones and other portable electronic devices (PEDs) produced interference in frequency ranges used by the Global Positioning System and aeronautical radio.

Are amusement and incessant communication worth the risk? As CMU's researchers point out, the FCC and FAA could better coordinate their EMI research and threat-assessment efforts. In addition, manufacturers could equip commercial aircraft with broadband RF analyzers that could sample EMI in the passenger cabin and, upon finding inappropriate levels, light a sign to warn passengers to turn off portable electronic equipment or risk getting fined. The analyzer could also log interference incidents in the aircraft's flight data recorder, just in case passenger-induced EMI contributed to an accident.

In the meantime, shut up, switch off, and enjoy your flight.