The thing, SNS3, is that flying an NDB procedure with an RMI in the pilot's primary field of view, like you have in your 747, is a piece of cake, compared to flying one with the usual ADF kit in a GA spamcan which has the ADF screwed into the panel somewhere 4 feet to the right just above the instructor's right knee - OK if the instructor is an female with good legs and a short skirt
It's no different. There's always an excuse. It's hard to see. It's hard to use. Why can't I just use the GPS? It's outdated. Nobody ever taught me that. Mine's fixed-card. I have to do math. Yada, yada, yada. The truth is that you've got the same stuff, or various versions of it, in your airplane, and your airplane, and you over there in the corner...yours, too. The truth is that the NDB still has value, and as I said before, it's still commonly used in many parts of the world. That's why we have two...because we go all ove rthe world, and yes, we still use them, train for them, and are required to demonstrate them.
Why isn't the one at SFO viable? Ever flown out of SFO? There are enough approaches there already, it's busy enough, flying a proceure turn out of the NDB would put the place at a standstill. But for many places, the NDB is still a very viable navaid...more importantly, it's a relatively inexpensive navaid which can easily be put in and used where other systems could not.
I think SNS3g has answered his own question.
Non-sequitor. I didn't have a question.
The traditional-GA fixed-card ADF, OTOH, has to be continuously compared with the DI, and since the card will either be fixed with 360 at the top, or (if rotating) will often be set by the instructor to have 360 at the top, you have to do some constant mental arithmetic. I did all this crap with a very traditional VERY BRITISH CPL/IR (who could naturally reproduce from memory the whole matrix of all the different map projections and the properties of each one) and he just loved the mental arithmetic bit; adding and subtracting 5 or 10 or 20 degrees or whatever the whole time. While the DI itself is a piece of absolute crap drifting off by a few degrees every few minutes and having to be constantly adjusted from the liquid compass (impossible in any turbulence) while the DI in your 747 is slaved to a fluxgate mag anyway....
You should be constantly comparing your instruments regardless of what you're flying. It's called crosscheck, and it's a basic instrument skill. Most light airplanes don't have the altimeter integrated with the attitude display indicator either...then again my airplane doesn't...but somehow we manage to crosscheck those instruments and keep each in the scan...along with the airspeed, vertical speed, heading, other navigational inputs, and a host of other instrumentation we may elect to use such as engine gauges, etc.
A fixed ADF card isn't a handicap unless you're particularly lazy.
One thing the card does for you without having to know a single number is give you a relative bearing, which is it's true value. If you have a rotatable card you can quickly set in a heading and do zero math, but even if you don't...make all your course intercepts at 45 degrees and you only need cardinal references on the outside of the instrument...it's mindless. You don't need to think. If you find the ADF equipment to be a challenge, then it's time to go back to gradeschool.
If you're flying an approach and find that the needle drifts to the right the width of a pencil, then turn two pencil widths right, wait for it to drift one more, then take out one pencil. Not exactly rocket science...but then that's the beauty of the ADF.
It cracks me up when someone says they don't need that antiquated equipment in their Cessna. It cracks me up more when I point out we have it in the B747, and they they tell me they don't have that fancy equipment in their Cessna...see, you can't have it both ways. Who cares if your directional gyro is air driven, electric, or slaved via flux gate? We've got a wiskey compass in there just like anything else, and I don't just fly a big airplane...what applies in one applies in another. Big or small...an ADF is an ADF.
Learning the basics isn't "crap." Perhaps that's your problem...stop dropping extra money on avionics and learn the basics. Perhaps your instructor wasn't such a fool after all.