I've seen a few IAPs with the verbage "dual VOR recievers required" or something similar. I didn't know if there are many ways an approach can require dual recievers or if its only just when you don't have DME and you have to identify fixes as intersections.
Similarly, is it true that you don't know need two recievers to fly an initial approach segment that utilizes different PCG than the approach course? For example, with one NAV radio, is it legal to fly a procedure starting at VOR #1 as the IAF, fly outbound on the initial approach segment, then switch my single NAV source to VOR #2 with the approach course and fly the rest of the approach? I've heard it's not illegal, just not ideal to switch back and forth between freqs and radials, so just curious. If this is legal, any tips to do this?