Vertical Card Compasses vs GPS Compass Display

I have to agree. Perhaps it's just my ignorance, but when is the
direction that the nose is pointing useful information? My compass
works fine, and is a great source of amusement, but gives me little
useful information, other than helping guesstimate winds by comparing
it to my track.

When I fly airplanes, a compass is an incredibly useful tool. When I fly
gliders, it takes up panel space.

Tony V.
http://home.comcast.net/~verhulst/SOARING

On Sep 21, 12:00 am, wrote:
On Sep 20, 7:37 pm, "Bill Daniels" bildan@comcast-dot-net wrote:





"Tom N." wrote in message

ups.com...

On Sep 20, 8:09 pm, Bill Zaleski wrote:
On Fri, 21 Sep 2007 00:01:32 +0100, Martin Gregorie

wrote:
wrote:

Some of the GPS's have a compass display. Is that a viable alternative
to a vertical card compass (still having regular old style compass as
backup) ?

That works for me. I have a Garmin GPS II+ and the bearing page is my
preferred directional display when I'm flying. My compass is tucked away
at the bottom of the panel for emergency use only.

As it sounds like you haven't seen a GPS II+, here's a description. The
bearing page shows a circular disk containing a large arrow that points
at the selected waypoint. Round it is a ring showing the main compass
points. Like a compass card, the ring rotates so heading is always at
the top of the display. For good measure the heading and waypoint
bearing are also shown as three digit numbers.

Some other basic handheld Garmins (12XL, GPS III+, eTrex, GPSMAP 60 and
76) also have this display page.

You may still be able to find the older models (GPS II+, III+, 12XL) on
eBay. Of the current basic handhelds, the GPSMAP series look the best
suited for our use because all controls are on the front next to the
display. The Geko series are too small to be practical while the eTrex
series have their controls on the edges which probably makes a panel
mounted one harder to use.

A GPS can not, and will not display heading. No GPS can do this. The
most it can do is display track, which is also heading only if there
is no wind correction. It can not be substituted for a compass.- Hide
quoted text -

- Show quoted text -

I love my vertical card compass. It is a PAI-700. I have it mounted
on the bottom of the pedestal where I occasionally look at it. No
problems with sticking. I use it to verify rough heading before my
GPS has a chance to register my track. In some parts of the country
the landscape is monotonous without distinguishing landmarks such as
mountains or ridges. I also believe that a compass is required
equipment for any aircraft - GPS is not a substitute.

Tom Nau

We need an FAR reference.

Does the FAR say that ALL aircraft MUST have a compass? Or does it say that
the aircraft in question must be equipped as shown in the Minimum Equipment
List found in the certification documents and reflected in the POH? I think
it's the later where if the POH doesn't list a compass as required
equipment, you can fly without one. Of course, MOST aircraft POH's do list
a compass - but not all.

Yes it's true that ordinary GPS receivers do not generate and display
compass heading - but some do. These are dual-antenna, carrier-phase
receivers that generate compass heading data referenced to TRUE NORTH. This
heading data is in NMEA format that some glide computers can use to generate
extremely accurate real-time vector wind.

Whether a particular receiver does or does not display compass data, ground
track is far more useful anyway. I care about the direction I'm going much
more than the direction I'm pointing. A long time ago I was given a vector
of 270 degrees magnetic when there was a 50 knot north wind. The resulting
ground track was WSW. The controller grumbled at me until I turned NW to
achieve a ground track of 270. The ATC controllers were much happier with
me when I flew ground track vectors.

Bill Daniels- Hide quoted text -

- Show quoted text -

I have to agree. Perhaps it's just my ignorance, but when is the
direction that the nose is pointing useful information? My compass
works fine, and is a great source of amusement, but gives me little
useful information, other than helping guesstimate winds by comparing
it to my track.
Jim- Hide quoted text -

- Show quoted text -

Hey Jim,

It seems to me that about once every year or two, usually on my first
day at an unfamiliar site, my expensive electronic gadgets decide to
take a brief nap. Usually, this occurs just as I'm about to roll
out from a thermal and head to some obscure turnpoint which is "more
or less NW". As I'm opening the apple core window and contemplating
whether or not to chuck the ***** PDA out, I glance at that little
round doohickey up on the glare shield. It provides reassurance
that, yes, I really am headed generally NW and buys a little
relaxation time while I recall various incantations to the God of
Electrons.

P3

On Sep 21, 2:41 am, Jose Jimenez nospam@please wrote:
Bill Daniels wrote:
We need an FAR reference.

No idea about FAR, but in JAR country, a magnetic compass is required
for motorgliders (self sustainers count, too). No magnetic compass is
required for gliders without a fuel to noise converter.

Bill, you are correct. FAR 91.205 requires a compass for powered
aircraft. No mention regarding gliders. FAR 91.213 requires a
compass for gliders only if it was part of the the equipment
prescribed under which the aircraft was type-certificated. However, I
still feel that a compass is very useful.

Tom Nau
JG

On Sep 20, 1:19 pm, wrote:
How well do the vertical card compasses work and hold up in real world
conditions ( constantly circling, sticking etc) ?

Some of the GPS's have a compass display. Is that a viable alternative
to a vertical card compass (still having regular old style compass as
backup) ?

I would welcome replies from those with experience with either or
both.

Stan

Thanks for your input. As always, your insights are very valuable.
Stan

wrote:
I have to agree. Perhaps it's just my ignorance, but when is the
direction that the nose is pointing useful information? My compass
works fine, and is a great source of amusement, but gives me little
useful information, other than helping guesstimate winds by comparing
it to my track.

I imagine that if you are trying to find landmarks in a strange country,
you'll need your heading. But it'll have to be a pretty fierce wind to
make your course and heading diverge enough to make it hard to substitute
the one for the other in that case.

--
Michael Ash
Rogue Amoeba Software

there are no instrument requirements for gliders in the FAR's. So if
you have a type certified glider the only thing that governs you would
be the Handbook or the Type Certificate. For experimental, it
completely depends on your operating limitations that were issued with
your airworthiness certificate. My Cherokee's Op Lims say that I must
be equipped IAW 91.207, so I have a compass. The only reason I have a
compass is to keep the FAA happy. its a normal "whiskey" compass and
bobbles around constantly.

On Sep 21, 9:39 am, wrote:
there are no instrument requirements for gliders in the FAR's.

The compass requirement may be found on the Type Certificate Data
Sheet.

14 CFR (aka "FAR") 91.205 (addressing POWERED aircraft...which would
include motorgliders) says that aircraft must have a magnetic
direction indicator.

While it may not spell out "g-l-i-d-e-r", having one to avoid pain
during a ramp check might be worthwhile.

I have PAI-700's in both my glider and power plane. Some times they
work well, some times they're less desirable than the old whiskey
compass (e.g., in a nose high attitude...). On some airplanes, the
vertical card compass is superior (a Bonanza I used to fly comes to
mind). The chief advantage is a good picture of current vs. desired
heading (or heading to a landmark...maybe useful when navigating near
restricted airspace). Be sure to have a compass correction card on
board...I got dinged by the absence of the sheet...fortunately by my
A&P during an annual inspection!

I've never had a compass stop working because the batteries were
dead. Maybe that's why they're required?

-Pete
#309