A couple of things, I reckon jamair is spot on regarding SA. If I'm flying a VOR approach & there's an NDB as well, the NDB/ADF is great for maintaining orientation on the VOR approach. I think the yanks are approved to fly GPS overlays aren't they? Makes an NDB approach even safer (as long as it's runway aligned :E)

Secondly, an ADF is horrendously expensive to install these days when you compare to glass. They are ripping NDB's out of the ground, so what is that saying? Goodbye NDB approaches I reckon.

So why do we have a lot less CFIT accidents on approach or even en-route than we had when they were the only game in town?

Were those pilots in the 30s, 40s and 50's simply not trained well enough?

I'm with big pistons here: sure they may have been acceptable in the past but things have moved on. There are much safer and cheaper alternatives.

When I teach students NDB orientation and intercepts, they all start by coming up with complex rules of thumb that inevitably fails about 30% of the time with them turning the wrong way.

As soon as you teach them to read the HSI/RMI like a map, they go straight to 100% accuracy and know exactly where they are, know where other aircraft are and can orientate themselves effectively, including increasing efficiency by manoeuvring directly overhead outbound, etc. I'm not sure if you can takeoff directly into a climbing turn and join the sector entry if you had a fixed card...anybody correct me on this?

Add in point-to-point intercepts and they can fly to any point in space within about 0.3nm by just looking at the RMI.

And that's out-of-date tech. It used to puzzle me why airlines put their HSI as sectorised when their SA would be increased by having a full compass. I now realise that their tech has moved on and the magenta line is safer than my full compass RMI/HSI setup for navigating. Just the march of progress.

Why don't you try a single engine, fixed card ADF aural null homing. Ah those where the days!! The VAR was ok as well

There's a lot of satisfaction in flying an NDB approach and getting it right but its still outdated inaccurate expensive technology. The GPSRNAVs are much more accurate but in my opinon, the most dangerous of all approaches. They are not well designed, unforgiving and its too easy to end up very dead.

I'd disagree with you Clearedtoreenter. With the proper training and understanding of the systems involved, and maintaining situational awareness, I find that GNSS based approaches are one of the safest approaches. You can have guidance with regards to actual track, as well as (more) runway aligned final approach tracks, and constant CDI scaling.

RAIM and FDE assists, and you can be fairly sure that what your GPS is telling you to do is accurate. Try saying the same about an ADF refracting off coasts, hills, pointing you to the nearest CB, and generally wallowing in the general direction of the beacon. GNSS certainly isn't all roses, but I know what I'd prefer on a bad weather night...

I think the safest technology I have ever seen is synthetic terrain (on a cirrus). I walked away from the flight with the impression that CFIT is nearly impossible.

Won't be long (maybe 5-10 years) before we see a pprune post "Vanilla artificial horizon dangerous" and the merits/reward of flying without being able to see the ground.

One day there will be a limited IFR rating that only allows use of synthetic terrain systems.

Much in the same way we have them for single power lever CSU and centreline-thrust twins.

"Fly through the boxes and you won't get hurt".

...and finnishing out the thread..:)

"...They are ripping NDB's out of the ground, so what is that saying? Goodbye NDB approaches I reckon."

Hmmm... probably wouldn't want to lose them NDB's yet. May need them when them terrorists get a bit more serious with them GPS guided drones. Only real way to stop them will be probably mean No GPS...






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