In article , Sydney Hoeltzli
wrote:

Looks to me as though the FAA could have installed ILS
at about 500 GA airports for the cost of WAAS, and
people would be flying 'em today

There are 40 ILS frequencies. Thus, frequency management
is a "challenge."

There are very tough siting criteria for installation
of ILS, especially the GS. Some airports that could
get WAAS or LAAS approaches can't have ILS.

--
Bob Noel