wangus

On my recent IR renewal, one of my procedures was to track to ROMTI, (Lydd) join, and perform a hold. I tracked inbound to ROMTI using my PFD Bearing 1 selected to ROMTI using Direct on the G1000. (I was flying manually, also tracking FROM SFD.) I used the pointer to perform a parallel join. I also had PFD Bearing 2 selected to LZD as a backup, and DME from I-LDY. I briefed the examiner that I was using ROMTI as my fix, and using Bearing 1 pointer to effectively fly it like an NDP. He told me I should be using LZD as my fix. He told me my primary NavAid should be the LZD and I-LDY 4.4 DME. I was using that as my secondary fix, but why couldn't I rely on ROMTI and GPS direct pointer to ROMTI?? It worked out fine, and I flew / navigated as he requested, but thought surely it is safer to fly the ROMTI fix with Bearing 1. I also performed a genuine IFR RNAV approach later on using GPS Waypoints back to base. Why are the RNAV waypoints acceptable to use for the approach, but not to use as fixes for holds??? I hope my question makes sense.
NOTE: My initial IR training was done on traditional mechanical gauges / instruments, (BE-76) so used to the old way. First excursion with G1000.

Anonystude

I had the joy of the Lydd NDB 21 on my initial IRT (in a G1000 equipped airframe). I was allowed to use GPS guidance to ROMTI as long as it was single needle tracking (and with moving maps disabled) -- using pure NDB/DME you'd presumably have to route to LZD first as you can't guarantee RNAV through old-school point-to-point nav to LZD 331(?)/4.4...

Cobalt

wangus,

For the test, the examiner wanted you to use the "official" primary nav-aid, which is LZD and the DME from ILDY as published on the chart.

For GPS approaches, the "official" primary nav aid for the approach is the GPS, so it is ok for the approach.

Next time, do what you did (display both the GPS and classic navaids, good airmanship), but reverse what you call "primary" and "secondary" (say "I am on QDR 353 and 4.4 DME, which is ROMTI, confirmed by the GPS").

As far as the "why can I not substitute GPS for NDB" is concerned, there is no polite answer. In the US you would have been able to use the GPS overlay to the NDB procedure including the hold, even without an ADF on board, provided that
1) the Approach is not labeled "GPS Overlay not authorized"
2) you have loaded the approach data from the database
3) you have done the necessary RAIM checks, as for any GPS approach

(PS - you DID check RAIM for the GPS approach, didn't you?)