Flight attendants make the same announcement when every airplane is about to take off or land: “Please power down all your portable electronic devices.” But will leaving your iPad, Kindle, or cell phone on really endanger the aircraft? Experts are divided on the subject. Those on the “it’s not dangerous” side say that at least one person on every flight probably forgets to turn off a device. So, if the signals did interfere with plane navigation and flight systems, there’d be more crashes. And newer planes have more sophisticated protection from electromagnetic interference.

So, what do the “it’s dangerous” experts have to say? First, the airline industry is about 20 years behind the cell phone industry and there are a lot of older planes in the air. They warn that electromagnetic waves emitted from all electronic devices could interfere with an airplane’s navigation and flight systems, and might even cause a crash. Safety experts don’t have any solid proof, but electronic interference is suspected in at least two different incidents.

For example, the pilot of a charter flight in New Zealand made a phone call and forgot to hang up. It interfered with the plane’s navigation system, and 8 people died when the plane crashed short of the runway.

Bottom line: The FAA would rather be cautious when it comes to digital devices on planes. And since there are so many different types of planes and personal electronics, and the technology is constantly changing, it’s impossible to lift the overall restrictions at this point. And if you don’t turn it off, you could get arrested.