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, (36) have reported well over 100
incidents that could have been (37) by electromagnetic (电磁的)
interference. The source of this interference remains unconfirmed, but
(38) , experts are pointing the blame at portable electronic
(39) such as portable computers, radio and cassette players
and (40) telephones. RTCA, an organization which advises the
aviation industry, has (41) that all airlines ban such
devices from being used during " (42) " stages of flight,
particularly take-off and landing. Some experts have gone further, calling for a
total ban during all flights. (43) , 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, (44)
. The difficulty is predicting how electromagnetic
fields might affect an aircraft’s computers. Experts know that portable devices
emit radiation which effects those wavelengths (波长) which aircraft use for
navigation and communication. But, because (45) .
The fact that aircraft may be vulnerable to interference raises the risk
that terrorists may use radio systems in order to damage navigation
equipment. (46) .