In my furthering attempt to understand the accident mentioned in this post, I've become interested in how WWII Bombers would have flown on instruments. In the accident report, the pilots states:
After passing Naknek en-route Elmendorf Field, we tried to go through Bruin Bay Pass but the Pass was closed. We climbed to about 7500 ft. and were between two layers of overcast. The layers began to converge ahead of us and before we knew it we were on instruments. Icing was severe and the antennas were lost in a very few minutes. Static was so bad on the loop antenna that the Anchorage range could not be heard. We thought our position was further East, over Cook Islet, until Co-Pilot, Lieutenant Donaldson, saw a mountain just off our wing tip and shouted to me. At almost the same instant we struck the mountain. After we got into the overcast everything seemed to happen so fast we couldn't do anything about it.
As a PPL and a budding instrument pilot, I am, of course, fairly well versed on how VORs and ADF/NDBs work. However, It is unclear to me whether when the pilot refers to the "Anchorage range" and the "loop antenna" whether he is talking about either one of these instruments/station types. He also mentions not being able to "hear" the range, which I would guess is similar to identifying a station with morse code the way VOR/ADF is identified today, though again, that is a guess.
Since the B-18 was much less common than the B-25 or B-17, there is much less written on them. I did find this article, but it does not go into detail on the types of instrumentation.
I've also tried to find a decent picture of the B-18a instrument panel, but so far this one is the best I've come across:
The instrument between the compass and the turn coordinator looks a bit like an ADF, but I think the image is too fuzzy to tell for sure.
I've also seen this very informative set of answers though I don't think they answer my specific question.
So again, my question is, what navigation aid(s) would these pilots have used while flying on instruments?