Setting altimeters with no radio

Peter Duniho wrote:

".Blueskies." wrote in message
t...
What about GPS precision approaches...where does the glideslope
information come from?


WAAS?

WAAS is insufficient for a precision GPS approach.

Nonsense. A fully deployed WAAS can provide precision GPS appoaches with
performance comparable to ILS (Cat 1).

GPS precision approaches
use "LAAS",

Not necessarily. In addition to WAAS, JPALS may be used in the future.

which is basically the same as WAAS except that the differential
station is much closer to the airport

LAAS transmits signals on the UHF band. WAAS does not. LAAS can eventually
provide more accuracy.