IFR in the 1930's

I can see emulating an NDB approach with a GPS, flying the same pathway etc.
but for something to be a "real" NDB approach wouldn't you need some device,
an actual ADF or a manual DF antenna rig, that actually receives the radio
beacon signal and gives you a bearing to it? A GPS may give you a bearing
to a waypoint that has the same coordinates as the beacon antenna and/or
guide you over the same path you'd follow with the NDB approach, but unless
it's actually picking up the radio beacon from the ground station would it
count as a true NDB approach?

"Roy Smith" wrote in message
...
"Steve House" wrote:
Hate to sound dense but how do you fly an NDB approach without an ADF?

Old answer: RDF. At least in the marine world, this was the predecessor
to the ADF. I'm assuming this was true in the aviation world too?
Stands for Radio Direction Finder (as opposed to Automatic Direction
Finder). Same principle, the difference being with the RDF, you have to
manually turn the antenna to find the strongest signal. The workload
involved pretty much requires a dedicated radio operator or navigator.

New answer: GPS