In the computer world, we like redundancy. This way if something we
depend on fails, their is a ready to use backup.

So here we are flying into an airport that has an ILS for runway x. And
there is an NDB approach for that runway. Well, the NDB is unneeded
because there is the ILS. So the FAA has the NDB decomissioned.

So, there's an accident at the airport, some person manages to clip the
Localizer's antenna array, and so the ILS is down for 4 weeks.

But, the FAA decomissioned the NDB, and now runway x can't be used
during IMC.

Then there is the possibility that a VOR can be taken out of service
for some strange reason that will last for weeks. But because the NDB
is redundant...

Then if you happen to be a pilot that flies outside of the USofA, you
may find that NDBs are quite common and very cheap to maintain
compaired to a VOR and extremely cheap compaired to an ILS.

And just how easy is it to lose GPS functionality? How easy is it to
lose RAIM? In a time of war, we will lose RAIM. But an NDB or a VOR?

If we are at war, as the Government keeps telling us, then we need to
think of backup options, not killing off the one option that is cheap.
And because it is an NDB, it is not all that accurate at distance! No
more so than your local AM station.

Later,
Steve.T
PP ASEL/Instrument