Using GPS to navigate airplanes in the US is only incedental to its actual
purpose.

Mike
MU-2

"William W. Plummer" wrote in message
newsv34d.653$He1.339@attbi_s01...
Satellites are great for coverage but they are expensive to maintain (
$1B per year). Would it be possible to use all those cell phone towers as
GPS extensions, providing wide area coverage and increased accuracy? The
satellite constellation would serve as the "backbone" which provides
accurate time and position information to all those cell phone towers, but
within range, the cell phone towers will provide much more accurate
location info.