"Gary Drescher" wrote
Hm, the VOR could even be off by 6 degrees (for an in-air check) and still
be legal. In that case, even one dot of deflection could be lethal on that
approach.

Quite true. The scary part is I almost killed myself and a student
that way. We had a lesson one morning, I called for a briefing, and
there were two airports reporting IFR conditions. LVJ was the closer
one, so we went there (I'm a big believer in training in actual
whenever possible, even if it adds time to the lesson - owners tend to
be OK with that since they're just paying for gas) and the only
approaches were VOR and GPS. The plane had no GPS, but the VOR was
fine.

We got about 30 minutes of actual on the way out, but then the weather
started breaking up. Still, by the time we broke out we were being
vectored to the FAC so I had the student put the hood on and continue.

He was doing a fairly credible job of it (the air was bumpy) meaning
he was well within PTS standards at all times. And so I sat there and
watched as he performed an approach that should have been fine - and I
saw us head for a tower. Had we been in IMC, there is an excellent
chance I would not be here.

After this, we performed a VOR check in the air on this VOR. The VOR
showed 5 degrees off. In other words, it was legal. We later checked
it in the air on another VOR. On that one, it showed 2 degrees off.

Michael