Identifying RNAV VDPs

[Mike21380]

Hi all- this may be a silly question, but how do you identify the VDP when flying an RNAV approach? For LOC approaches this is simply a DME value, but what about on an RNAV approach? The approach plates give the VDP location in NM from the end of the runway, but where on a typical GPS would I find my distance to the end of the runway? Maybe I should be looking at my distance from the previous fix (like the FAF or a recently passed step-down fix), but the distance shown on a GPS is usually the distance to the next fix, not the previous.

Thanks!

 

[iamtheari]

The missed approach point for an LNAV approach is the runway threshold, so the GPS should show you the distance to that point once you are past the last step down fix.

 

[Mike21380]

Duh- I should have know that. Thank you!!!

 

[RussR]

The missed approach point for an LNAV approach is the runway threshold, so the GPS should show you the distance to that point once you are past the last step down fix.

Often, but not always. The MAP may be the runway threshold, or a fix prior to the runway threshold. If you haven't seen one like this, use Montrose, Co MTJ RNAV (GPS) RWY 35 as an example:
https://skyvector.com/files/tpp/1712/pdf/00668R35.PDF

For the OP:

The MAP on this example is BEQJI, 0.5 nm prior to the threshold. The VDP is charted as 1.4 nm to BEQJI, so when the GPS distance to BEQJI is 1.4, you are at the VDP.
If the MAP is the runway threshold, your GPS will show the distance to it after you pass the FAF (or a final stepdown fix if present). If your GPS screen is not showing you the distance to the next fix, you need to setup the display fields to do so.