an altitude of more than 10,000 feet. for many passengers, they understand the rule as it pertains to cellphones because they are constantly sending signals. however, many want to know why items that do not transmit data are prohibited like your mp-3 player or tablet or e-reader. an engineer with boeing says the answer is simple. >> the devices on the aircraft are very sensitive, receivers, very specific frequencies and modes of operation. the devices that you bring on may not be operating on those same frequencies but they do have electronic emissions that can find their way into the antennas or the devices on the airplane. >> they say they are open to reexamining the policy and having new discussions on how to test which devices can safely be operated in what is considered critical phases of flights.