When you take into account of all of the possible ignition sources around an aircraft when it is being refueled, I would think the least likely source would be a low voltage battery powered cell/mobile phone.
To be honest I never given the use of using a mobile phone during refueling operations a second thought. You have the exhaust from the refueling truck, the APU exhaust, the hand held radios used by the re-fuelers, flight crews using the aircraft radios and then of course me walking around with a lit cigarette in my mouth.
Just kidding about the cigarette now, don't anybody have a coronary.
