Dave Carson of Boeing, the co-chair of a federal advisory committee that investigated the problem of electronic interference from portable devices, says that PEDs radiate signals that can hit and disrupt highly sensitive electronic sensors hidden in the plane's passenger area, including those for an instrument landing system used in bad weather.
"It could be you that you were to the right of the runway when in fact, you were to the left of the runway," said Carson, "or just completely wipe out the signal so that you didn't get any indication of where you are coming in."
Asked if a cellphone's signal could really be that powerful, Carson said, "It is when it goes in the right place at the right time."
To prove his point, Carson took ABC News inside Boeing's electronic test chamber in Seattle, where engineers demonstrated the hidden signals from several electronic devices that were well over what Boeing considers the acceptable limit for aircraft equipment. A Blackberry and an iPhone were both over the limit, but the worst offender was an iPad. There are still doubters, including ABC News's own aviation expert, John Nance.
"There is a lot of anecdotal evidence out there, but it's not evidence at all," said Nance, a former Air Force and commercial pilot. "It's pilots, like myself, who thought they saw something but they couldn't pin it to anything in particular. And those stories are not rampant enough, considering 32,000 flights a day over the U.S., to be convincing."
Nance thinks there are alternate explanations for the events. "If an airplane is properly hardened, in terms of the sheathing of the electronics, there's no way interference can occur."
But Boeing engineers told us that signals from PEDs could disrupt the navigation and communication frequencies on older planes, which are not as well shielded as the newer models. And anything that distracts the pilots in the cockpit is considered a true threat to safety.