Is the use of a certified IFR GPS receiver approved for identifying fixes defined by VOR radials, on a conventional (non RNAV) instrument approach? For example, in KCDW LOC RWY 22, the intersections DOWDY, FAAIR and KOLLI (IF, FAF, step down fix, respectively) are all identified by VOR cross radials (TEB VOR). Can they be identified solely by reference to the GPS database? Another example would be KABE LOC RWY 13; IZKIP is a step down fix identified by a cross radial from ETX VOR. However, the chart states:
IZKIP FIX MINIMUMS (DUAL VOR RECEIVERS REQUIRED)
Can a GPS be used to identify IZKIP in this case?
According to AC 90-108:
...operators may use a suitable RNAV system in the following ways... Determine aircraft position relative to or distance from... a named fix defined by a VOR radial.
Therefore my understanding is that named waypoints/intersections defined by VOR radials on a conventional IAP like in the examples above, can be identified using a GPS, except perhaps when the chart requires dual VOR receivers.