[net.aviation] Glideslope

good@pixar (Never tell your copilot "Cheer up" during the takeoff roll.) (02/26/86)

	Someone just pointed out via mail (thanks!) that what I said about
using the glideslope before getting on the localizer can be very dangerous.
(Just ask the NTSB...)

	I should have been more specific.  The approach I had in mind was
one where we knew that we were getting very close to the localizer, and
we also knew that we had to lose altitude before getting established on it.
We also knew that we could descend to whatever altitude that was without
dropping below MSA for that area.  Using the GS a minute early simply prevented
us from having to drop like a rock to get to the right place.  The idea
that you should check your altitude at each appropriate fix to make sure you
are on the real GS still holds.

	I had meant only to illustrate that the GS is independant of the
localizer.  I shudder to think that some guy ten miles from the approach
fixh might follow the glideslope into a cumulo-granite cloud thinking,
"gee... didn't that guy on the net say this was ok to do?...".    :-}

		--Craig
		...ucbvax!pixar!good

ark@alice.UucP (Andrew Koenig) (03/01/86)

>	I should have been more specific.  The approach I had in mind was
> one where we knew that we were getting very close to the localizer, and
> we also knew that we had to lose altitude before getting established on it.
> We also knew that we could descend to whatever altitude that was without
> dropping below MSA for that area.  Using the GS a minute early simply prevented
> us from having to drop like a rock to get to the right place.  The idea
> that you should check your altitude at each appropriate fix to make sure you
> are on the real GS still holds.

I don't think that's right.  There is presumably a minimum altitude to
fly until you're on the localizer, and you shouldn't descend below
that altitude until you're established.  This is true even if the
glideslope makes it look like you're actually established.

good@pixar (Nuke 'em 'till they glow, then shoot 'em in the dark.) (03/06/86)

In article <5060@alice.uUCp>, ark@alice.UucP (Andrew Koenig) writes:
> >	I should have been more specific.  The approach I had in mind was
> > one where we knew that we were getting very close to the localizer, and
> > we also knew that we had to lose altitude before getting established on it.
> > We also knew that we could descend to whatever altitude that was without
> > dropping below MSA for that area.  Using the GS a minute early simply prevented
> > us from having to drop like a rock to get to the right place.  The idea
> > that you should check your altitude at each appropriate fix to make sure you
> > are on the real GS still holds.
> 
> I don't think that's right.  There is presumably a minimum altitude to
> fly until you're on the localizer, and you shouldn't descend below
> that altitude until you're established.  This is true even if the
> glideslope makes it look like you're actually established.

	That minimum altitude is the one I meant.  No way am I going *below* it
until I'm on the localizer and at the appropriate fix.  I'm just starting
*towards* it if I happen to still be above it.  You gotta come down anyway
in that case, and the GS is very likely to be a good way to get you there.
Remember, we're talking *very close* to the localizer anyway.  Maybe I should
just be quiet for a while...

		--Craig
		...ucbvax!pixar!good