Lifting the ban on cell phones during flights, a change being considered by the Federal Communications Commission, may be a bad idea: portable electronics can potentially interfere with GPS navigation, which has been increasingly used during landings. Carnegie Mellon University researchers stowed, with permission, a wireless frequency spectrum analyzer onboard 37 commercial flights in the eastern U.S. They found that passengers made one to four cell phone calls per flight. Moreover, the group discovered that other onboard sources (possibly DVD players, gaming devices or laptops) emitted in the GPS frequency, consistent with anonymous safety reports that these devices have interrupted the function of navigation systems. “There's enough to leave you feeling queasy about opening the floodgates to lots of other radiating sources,” says M. Granger Morgan, co-author of a report published in the March IEEE Spectrum. If the ban were lifted, portable electronics would still have to comply with airline regulations that prohibit cockpit interference.