How do you fly a GPS approach then? I have no IR but I would assume that you would use the CDI/GS (slaved to the GPS) as primary guidance.
That is true...
I would guess that if you are driving a dumb CDI from a GPS, the CDI flag
has to be connected appropriately.
That is an issue in the avionics business; some installers just throw in a GNS430, connecting up the basic wires and that's it.
Normally, of course, you use the autopilot and monitor the approach on the moving map, on which the entire approach is depicted
One would not just watch the CDI and not the GPS because, for example, one needs to be sure the GPS is correctly sequencing to/through the approach, with the sensitivity dropping from 5.0nm enroute to 1.0nm by the IAF, to 0.3nm at/past the FAF. This stuff is only on the GPS screen.
It was a while ago but for my IRT we added 50' to the MDA but not to the DA. A practice which is common now in the name of stabilised approaches, non precision. It becomes a 'virtual' DA where one can initiate a GA at this new DA and with any inertia still not bust the MDA.
Interesting... I was told differently: add 50ft to the published ILS DA, but add nothing to the published NP MDA. With the ILS you go missed at the newly calculated DA and climb straight up. With the NPA you fly level from the point where MDA is reached (at an altitude which is between the published MDA and that plus 50ft) all the way to the MAP and then climb. If you bust either figure you fail, and if on the NPA you climb outside that 50ft band (before the MAP) you also fail. I will need to revisit this when I get the plane out of the Annual...