by Brett_Henderson » Tue Nov 27, 2007 11:34 pm
Yeah.. NDB navigation is a dying art. As the old transmiters wear out, they aren't being replaced or repaired.. And the NDB reciever / ADF gauge is a maintanence head-ache to keep tuned.. AND it's heavy... along with the fragile antenna.
The NDB approach is just like a VOR approach.. except that instead of a nice radial to track; you've got the nebulous, ADF pointer. And instead of the accurate CDI, you the pilot have to "gauge" your track. Keeping the needle on runway heading while adjusting for the wind, just takes a little practice.
The other important use for NDBs, is as outer markers. They can keep you from turning runway heading too early. And of course they can be used along with a VOR (or second NDB) for triangulation.
Another short-coming, is their range... 30-40 miles tops. BUT... they can be tuned to an AM radio station too. If your home airport is at a city with a 50,000watt AM station... you can always find your way home ;)