I'm sure you're not seriously suggesting that someone would be flying for-real IFR in 2017 without a GPS in the aircraft.
Well, me (waving hand). Though it was 2015. But there I was, having to fly what amounted to a for real IFR approach, in what was generously agree were special VFR conditions. The 182 I was flying is equipped with a KX165 (ILS & Glideslope) and a KR87 ADF. It also is equipped with a Garmin GTN750 GPS Comm, Garmin G500 glass cockpit, and a full set of "steam gauge" instruments. And, a complete set of approach plates for the airport.
I'm confident that the GTN750 coupled to the G500 is ultimately capable of presenting everything a pilot could
want to fly an awesome GPS approach. But, the KX165 and KR87 provided what I
needed. I flew the approach as best I could relative to the approach plate, with the tower's concurrence, and did just fine. I ignored the GPS so as to prevent task saturation, and everything worked out just fine - just as it always did when I would fly several actual ILS approaches in the Aztec each week in the early '80's - before GPS was known.
I do accept that ADF and ILS will be decommissioned, and some of us dinosaur pilots will have to learn new techniques. But, in the mean time, the equipment is there, it is reliable, and happily easy to understand.
I have flown long night winter legs over unpopulated areas with an ADF being the only means of navigation, and it worked just fine. My friend and I flew the length of Africa in a Twin Otter, in which though there was a VOR/ILS, the two ADF's turned out to be the better means of long range navigation at Twin Otter altitudes. Again, before GPS (though my friend had some kind of pre GPS sat nav unit (about the size of a typewriter), which consumed a lot of his interest, with him merely popping up from time to time to tell me I was on course.
To my amusement, and his frustration, I found a trick. This aircraft had dual RMI's, with no directional gyro (so the compass cards behine the ADF pointers would show the magnetic heading based on a remote wing mounted compass head). The RMI's would fail from time to time while we flew. They would drop a flag, and the card would no longer turn. No longer useful as a heading indicator - or were they?
He confirmed with his sat nav, over disappointingly long intervals that I was keeping my heading really well, considering that the most I had to use was the wet compass. How was I doing it? I would not tell. At the end of the trip, I had to answer up, so he did not explode with curiosity. I noticed that if the RMI card failed and stuck on the desired heading, I could use the RMI slaving meter as a quasi VOR indicator. If I turned even a degree off course, the slaving meter would try to slave the RMI face back, but could not, so it would show "unslaved". I could reslave by returning the aircraft to the required heading by reference to the slaving meter indication. It worked a treat, and very precise. But the downside was that it required an RMI to fail on the desired heading.
The very long distance [away] NDB's supplemented this crude navigation means, because the ADF
could receive those signals. .