john smith wrote in
:

Google "FAA, sole source navigation, GPS"
There are many articles out there.
From what I skimmed, we are still in transition to becoming sole
source.
Sole source is dependent upon other parts such as WAAS and LAAS becoming
accepted as operational.

But in this case, GPS is not being used as a sole source of navigation, just
for one part of one approach. Using the sole source logic, no GPS approach
would be legal.

--
Regards,

Stan