SAC ILS "ADF Required" Info

Jose wrote:
Mr

McNicoll
is correct is stating that he is allowed to substitute GPS for ADF in
certain circumstances. However we have to consider the least possibly
equipped aircraft shooting this approach and that requires that we place
an
"ADF REQUIRED " note on this approach.


Why not "ADF OR GPS required"?

Jose

Good question. I'm sure that will be an option in the not too distant
future, but right now you can't mix and match ground-based systems with
GPS on published procedures due to TERPS requirements. That's another
set of guidelines that allows substitution with GPS in some
circumstances, and already you may have seen NOTAMS stating "Procedure
NA except for IFR certified GPS equipped aircraft" where the NOTAM
specifically allows substitution for DME or ADF ancillary equipment.

John