Industry report: Cell phones, electronic devices can cause trouble on planes

The announcements are familiar to anyone who’s traveled by plane before: “Please turn of all personal electronic devices,” a flight attendant will tell travelers before take-off. The request is often ignored by fliers who are skeptical the devices pose any safety threat.

"I can't imagine my measly cell phone is going to cause anything bad to happen,” said Chris Manna.

But a confidential industry study obtained by ABC News indicates Manna might be wrong. The report by a trade group representing more 230 airlines documents 75 incidents of possible electronic interference. Airline pilots and other crew members believe those incidents between 2003 and 2009 were linked to mobile phones and other electronic devices.

Twenty-six of the reported incidents affected the flight controls, including autopilot and landing gear. Navigation and communication systems were also affected, ABC News reports. Cell phones were suspected in four out of ten cases.

The report doesn’t verify that phones or other electronic devices actually caused those complications, instead listing anecdotal experiences by crew members and pilots. In one events described, a clock spun backwards and a GPS in cabin read incorrectly while two laptops were being used nearby. During another flight, the altitude control readings changed rapidly until a crew member asked passengers to turn off their electronic devices, when the readings returned to normal, ABC News reports.

The report says portable devices radiate signals that can hit and disrupt{ } sensitive electronic sensors. "The equipment that feeds the data to the cockpit, the radios and the communications and navigations equipment itself is located under the floor of the plane or in the overhead or in the walls,” said Dave Carson of Boeing.

ABC News’ own aviation expert John Nance is skeptical of the impact of electronic devices.

"There is a lot of anecdotal evidence out there, but it's not evidence at all," Nance, a former Air Force and commercial pilot, told ABC News. "It's pilots, like myself, who thought they saw something but they couldn't pin it to anything in particular." The sheer number of flights – about 32,000 a day over the U.S. alone – means incidents such as the ones described happen frequently, Nance told the network.