It actually happened today!! Vacuum failure in IMC.

Dave,
I'll use this to answer both you and Barry, since you have both raisede
the WASS question, but you have a second one.

The rnavs 5,11, 23, and 29 at CAE have an entry that is "LNAV/VNAV".
I'm new to the panel GPS, having just gotten it about a month before
this trip so, although I have flown the approaches when familiarizing
myself with it, I had not thoroughly studied the GPS approach plates.
Before I left AVL, I'd looked at the plates and saw those notations,
and didn't look further. They require WAAS. I now (for the first
time) see that there are also simply LNAV approaches. I'm more
familiar with ILS than GPS approaches (obviously), and planned on an
ILS approach anyway, so hadn't really studied the GPS approach plates.
As for flying the GPS rather than the ILS into CLT, I've been so
indoctrinated into flying headings rather than "chasing the needle" on
an ILS that I had to rule that out. Although I was wrong about the
need for WAAS, I believed that I had no choice at that point-I'd do the
best I could with the GPS approach. The ceilings and vis were better
at CLT than at CAE (which was close to minimums) so it was less of a
risk (in my mind) to do the GPS approach at CLT even though I wasn't
(erroneously) properly equipped with WAAS.

As for flying the GPS rather than the ILS into CLT, I've been so
indoctrinated into flying headings rather than "chasing the needle" on
an ILS that I had to rule that out.

I agree with flying a GPS approach instead of an ILS when partial panel - it's
much easier to fly because the needle doesn't get more and more sensitive as
you continue. Another factor to consider is that with only the magnetic
compass it's easier to hold an east or west heading than north or south. So,
for example, at CAE, I'd ask for the GPS 11 or 29 instead of 5 or 23.

Barry

Barry wrote:

As for flying the GPS rather than the ILS into CLT, I've been so
indoctrinated into flying headings rather than "chasing the needle" on
an ILS that I had to rule that out.


I agree with flying a GPS approach instead of an ILS when partial panel - it's
much easier to fly because the needle doesn't get more and more sensitive as
you continue. Another factor to consider is that with only the magnetic
compass it's easier to hold an east or west heading than north or south. So,
for example, at CAE, I'd ask for the GPS 11 or 29 instead of 5 or 23.

I'd fly an ILS over a GPS any day if I was PP. I WOULD use the GPS to
give me a better indication of the heading as opposed to the compass,
but why give up the lower minimums and greater accuracy offered by an
ILS, especially when the chips are already down a little.


Matt

I'd fly an ILS over a GPS any day if I was PP. I WOULD use the GPS to give
me a better indication of the heading as opposed to the compass, but why
give up the lower minimums and greater accuracy offered by an ILS,

Because the GPS approach is easier to fly - less chance of going to full-scale
deflection.

Barry wrote:
I'd fly an ILS over a GPS any day if I was PP. I WOULD use the GPS to give
me a better indication of the heading as opposed to the compass, but why
give up the lower minimums and greater accuracy offered by an ILS,


Because the GPS approach is easier to fly - less chance of going to full-scale
deflection.

If you aren't proficient enough to fly an ILS to minimums on partial
panel, then you probably shouldn't fly in IMC until you get some
refresher instruction. I don't know what GPS you use, but the old King
89B I use is a lot harder to set up for an approach than is the ILS. If
I was flying partial panel, I'd much rather twist in a frequency, ID and
be done, than have to pull up the airport from the active page, dial
down to the proper approach, load it up, and then be sure I remembered
to select OBS mode during vectors, then LEG more before the FAF, watch
all of the intermediate descent altitudes, etc. The ILS is just so much
simpler and it is more accurate to boot (I know, this is being changed).

I still don't consider GPS approaches to be progress over the good old
ILS and even VOR approaches. I realize the advantage of having
approaches at airports that had none before, and that is certainly a big
advantage. I just wish the engineers at King were pilots! I'm an
engineer, so I feel I can say this ... the KLN-89B definitely seems to
have been designed by an engineer and for an engineer, not by a pilot
and for a pilot.

I understand the new glass displays are much improved in user
friendliness, but I've yet to have the good fortune to fly behind one.


Matt

Yea, I debated in my mind whether to do ILS or GPS. I'm more familiar
with ILS, but opted to put all my nav info on the one instrument (GPS)
since I was already using it for course guidance. It seemed like it
would be easier at a time that I needed simplicity in my life, and just
as safe. On another occasion I might make a different decision.
However, I made the decision and deceided to stick with it.

Barry wrote:

I'd fly an ILS over a GPS any day if I was PP. I WOULD use the GPS to
give me a better indication of the heading as opposed to the compass, but
why give up the lower minimums and greater accuracy offered by an ILS,

Because the GPS approach is easier to fly - less chance of going to
full-scale deflection.

That's not necessarily correct. How many step-downs are there vs. how many
can you keep in your head? Of course, there can be step-downs to the GS
intercept on an ILS, but none after that (when the localizer is getting
tight).

Personally, I find an ILS to be the easiest type of approach in general
because of its reduced workload. And since one can still cheat with the
GPS providing track and track error, it would be relatively easy to hold
the needle centered (easier still with a WAAS-capable unit, of course {8^).

- Andrew