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[Entry]
"3G or HDSPA modems work pretty much the same way as cellular or mobile phones, so the following article will apply:
Anyone who has flown on an airplane in
the past few years has heard the stern
warning from the flight attendant
about turning off cell phones and
other portable electronic devices.
Airlines warn that the signals from
cell phone transmissions can disrupt
navigation systems and pose a danger
to the aircraft. But is it even
possible to make cell phone calls
while in flight?
The simple answer
Following the terrorist attacks of
Sept. 11, 2001, news reports carried
stories of passengers phoning loved
ones in the minutes before the planes
crashed. Also, the Federal Aviation
Administration has conducted studies
indicating that despite the warnings
from flight attendants, an average of
one to four cell phone calls are made
from commercial flights in the United
States. Obviously, then, cell phones
can operate in flight, at least under
certain conditions.
How cell phones work
Cell phones are basically radios which
connect to a transceiver located on a
cell tower. Each tower covers a
certain area, or cell, hence the term
cell phone. When a phone moves from
one cell to another while in use, as
in the case when the caller is in a
car, the tower ""hands off"" the call to
the next tower. Cell phones can
typically connect to a tower up to 10
miles away.
The qualification
Towers, however, are configured to
connect to signals at ground level, so
while someone on the ground or in a
car may be able to connect to a tower
several miles away, that range is much
shorter when flying at 35,000 feet.
Also, a cell phone transmitting from a
high altitude may connect to several
towers at once, resulting in a
scrambled signal. And while the
cellular network can easily hand off
the call of someone traveling at 70
miles per hour, the task is much more
difficult when the caller is traveling
at 600 miles per hour.
The bottom line
While it might be possible to make a
cell phone call while in flight, the
bottom line is that chances are the
call quality won't be very good, if
you are able to connect at all. That
may be changing, though. Cell phone
companies are in the process of
developing equipment that can handle
calls from the air.
The downside
Unfortunately, allowing cell phone use
on airplanes will place airlines in
the position of finding ways to
control conflicts between passengers
because of inconsiderate cell phone
use. Congress is considering making
the ban on cell phone use permanent,
although the wireless industry is
resisting such a move. The airline
industry will most likely have to
develop a solution such as a ""no-phone
section"" in order to handle the
changes.
Source"
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