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Date: Wed, 18 Nov 1998 07:27:38 -0600
From: Snowbird <snbird@ibm.net>
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Subject: Re: Do U Trust Your Instruments?...
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St Stephen Ames wrote:
 
> Do you trust your instruments with your life?...

Well, we fly IFR in IMC, so yeah, we have to.

> I, after reaching my destination, decided instead of following the 
> same checkpoints that I did down that I would do some VOR Nav...

VORs can be really confusing.  Do you really understand them? 
If not, using a VOR is a good way to get yourself lost.  I
recommend Tim's Air Navigation Simulator:
    http://www.visi.com/~mim/nav/index.html
It's the greatest thing for understanding VOR nav since sliced
bread, and it's free.

Some stuff you should be able to do if you really understand VORs:
1) tell where you are relative to the station just by looking at
   the OBS
2) tell where you are relative to any radial which is dialed in,
   just by looking at the OBS
3) fly almost directly to any interesection just by looking at
   two OBS with the radials defining that intersection dialed in

Try to figure out the above with the 'map' portion of Tim's simulator
covered, then look to see if you "got it".

> tracking and passing the first VOR with no problem I dialed in the 
> next one and after about 5 minutes it seemed like I couldn't keep up 
> with the needle...

Did it ident properly and show a strong to/from indication?
It sometimes happens that a digit inside the radio slips, and
the VOR you're tracking isn't the one you think...the clue is
if the ident doesn't match.

Either that, or you flew directly over the station.

I can't tell from what you wrote, but usually the procedure is
to track the VOR you've just passed outbound for about 40 miles
before tuning in the next.  And when in doubt, see what a second
VOR has to say about where you are.

> Hindsight being 20/20 I saw 2 lessons  learned, first I should have 
> trusted my instruments and second I shouldhave maintained better 
> situational awareness regardless of how I was navigating...

Exactly.

> But again I ask, how far will you trust your instruments?...I realize > flying IFR means trusting your life to them but are they that 
> good?

Yes and no.  The really critical skill in IFR flying is "instrument
cross check".  This includes cross-checking turns, cross-checking
pitch, and cross checking where you think you are in terms of flight
time and heading, with the VORs.

In the short time I've been flying, I've had:
1) a bad ASI (not dead--incorrect, read lower than actual)
2) a bad DG (precessed 30 deg in 180 deg std rate turn)
3) a dead DG (failed on takeoff--spins around lazily)
4) a bad altimeter (not static system--hands stuck)
5) a bad AI--indicated 15-20 deg while banking 45 deg
6) a dead AI (never stabilized on startup)
7) a bad compass (some headings 30 deg off)
8) a bad OBS -- it passed the FAA VOR check but 10 deg off was 
  only 1/3 to 1/2 deflection, moral FAA VOR check not sufficient

(not all at the same time or all in the same plane).

So I don't trust my life to any one instrument.  Preflight checks 
are critical, and instrument cross-check in flight is critical.  
All of the above can be caught and identified with proper cross 
check. When looking at an instrument always ask yourself "if this 
were a lying piece of sh** how would I know?"

Snowbird

PS always carry instrument covers, a pad of post-its will do.  Having
an instrument spin around in front of your eyes or give out faulty
readings can be really distracting even if you know in your head it's
wrong.  Cover it up.

