The biggest safety threat (  ) facing airlines today may not be a terrorist (  ) with a gun, but the man with the portable (  ) computer in business class (  ). In the last 15 years, pilots (  ) have reported well over 100 incidents (  ) that could have been caused by electromagnetic interference (  ). The source (  ) of this interference remains unconfirmed (  ), but increasingly (  ), experts are pointing the blame (  ) at portable electronic device (  ) such as portable computers, radio and cassette (  ) players and mobile telephones.

RTCA, an organization which advises the aviation (  ) industry (  ), has recommended (  ) that all airlines ban (  ) such devices from being used during “critical (  )” stages of flight, particularly (  ) take-off and landing (  ). Some experts have gone further, calling for (  ) a total ban during all flights. Currently (  ), rules on using these devices are left up to individual airlines. And although some airlines prohibit (  ) passengers (  ) from using such equipment   ) during take-off and landing, most are reluctant (  ) to enforce (  ) a total ban, given that many passengers want to work during flights.

The difficulty is predicting (  ) how electromagnetic fields (  ) might affect an aircraft’s computers. Experts know that portable device emit (  ) radiation (  ) which affects those wavelengths which aircraft use for navigation (  ) and communication (  ). But, because they have not been able to reproduce (  ) these effects in a laboratory (  ), they have no way of knowing whether the interference might be dangerous or not.

The fact that aircraft may be vulnerable (  ) to interference raises the risk that terrorists may use radio systems in order to damage (  ) navigation equipment. As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too loud.