Phones and airplanes -- do you really have to turn it off? Frankly, that article didn't make me any less skeptical about the claim that phones can interfere with navigation instruments. "Before deciding whether to allow passengers to use phones before takeoff, several airlines conducted ground tests to see if cellphones would interfere with systems. At American Airlines, people dialed cellphones from out-of-service planes parked at various airports. 'They found no interaction with the aircraft instruments on any aircraft type,' said Tim Smith, a spokesman for American."