"The majority of general aviation flights are flown under VFR,
so there is seldom exclusive reliance on electronic navigation.
Plus, the pilot isn't isolated from the passengers and has the
immediate ability and responsibility to terminate the use of any
device at any time if it is interfering with flight-critical
electronics."
Source: Randy Kenagy, AOPA senior director of
advanced technology, testifying before the FCC on the benefits of
allowing cellular phones into the cockpits of general aviation
aircraft. AOPA says there's no sense in waiting -- the benefits of
having a cell phone in the cockpit far outweight the possible
problems.