On Tue, 20 Apr 2004 16:35:03 -0500, FUji wrote:

Greg Copeland" wrote in message
news snip
The general theory on modern cell phones in flight, goes like this:
The FCC also has a ban because when you're in flight, you're always at
least 6-8 miles away from the nearest cell tower. You end up communicating
with too many towers and bogging down the network. One or two such calls
is tolerable, but a whole plane load moving through would disrupt the
ground-based users of the network. Remember, the farther you are from a
tower, the more power your cell phone uses to communicate with it's tower;
up to 5-watts. Worse, a plane full of 5-watt transmitters causes
terrestrial interference problems for the land cell users, in a large
radius around the plane.
snip

Huh? Maximum output of most handheld cell phones is 0.6 watts with the old
in-car and bag phones going up to 3 watts. It can't output more than it's
maximum no matter how far you are away from the tower. The radius of
interference from 0.6 watt phones transmitting from inside an aluminum can
would be rather small. And it's a little hard to imagine a plane full of
people with bag phones.


Hmm. Everything I've ever read says that maximum output is 5-watts. I'm
not saying that's right, but that has been a constant. I'm not sure how
far you could even transmit on 0.6 of watt.

I also found a quote that went like this:
"The restriction against cell phones is an FCC regulation and applies to
all aircraft that can fly over a certain speed (maybe 200 kts?). Quickly
switching cells during high speed flight causes all sorts of problems on
the cell network."

The switching is done in a fraction of a second. The most that would happen
is a dropped call.

People forget that cell switching is not magical. And it's certainly is
not zero cost. I must admit I do not fully understand everything that
goes on, but I am sure it's not as simple as you imply. Everytime a call
switches cells, it creates lots of work for the cell network to make sure
only a single tower handles that call. So, while it may take a fraction
of a second from a given phone and a given tower, there is lots going on
behind the scenes. Worse, instead of it going on with one, two or maybe
three towers, now it's causing a flurry of on twenty or more (highest
estimates I've read) towers. Let's also not forget that each tower can
only process and multiplex n-number of signals at a given time. DSPs,
just like your CPU, does have finite capacity. During cell switching, as
I understand it, this finite resource is being used on each tower in
contact with the phone. So, to say, "it causes all sorts of problems on
the cell network", does seem like a spot on statement to me.