garmin 296

"Robert M. Gary" wrote in message
om...
But today my SkymapIIIc has airways. They are pink on the display. You
just put your white course line on the pink airway line and you're
flying down the middle of the airway. No need to figure out what VORs
or intersections are on the airway when ATC puts you on an airway.
Often, near SoCal they don't even name intersections. You'll get
instructions from approach like, "Victor 123 to Victor 234 to Victor
345, etc, etc". I've gotten as many as 5 victor airways in my
clearance as I approached SoCal, none of which included intersections
in the clearance. The SkymapIIIC sure made it easier. However, I just
bought the 296 because of the turn coordinator functionality (for
emergency partial panels no electrical and no vac) and for the battery
life after loss of power.

-Robert

All you need is a DB 9 connector, basic electronics knowlage and a good
rechargeable battery (12V 2 Amp Lith Ion surplus camera pack 18 Volt RC car)
and soldering knowledge my power pack cost me less than $25.00 to make for
my IIIc and will last a very long time almost 12 hours continuous use I also
built a inline charger so when it is plugged in to the airplane power outlet
it will keep the battery charged and switch to battery power in the event of
aircraft power loss. My battery fits nicely in the seat belt shoulder strap
holder in my 150.

"John Bell" wrote in message
om...
From: "Richard Hertz"


I have yet to try this myself, but two pilots I know suggested I try it.
The airways are defined by VOR radials. GPSs do not seem to navigate
them
correctly. In fact, one of the pilots mentioned flew with an
"instructor"
who was relying on a GPS for lateral guidance on an IFR flight plan.
The
pilot told the instructor to knock it off and use the vors as he was
seeing
CDI needle deflection. The instructor said not to worry.

After some time ATC informed them that they were off the airway (though
the
gps showed dead-on).

You should be able to navigate an airway more accurately using a GPS than
you can with a VOR.

You should be able to navigate using no GPS. Today there seems to be a
reliance on pretty pictures to tell us where we are. The trouble with that
is when the picture goes blank, or when the GPS does not put us on the
airway.

"Should" and what happens in reality are different things. No amount of
theory or web links are going to convince the FAA or a controller that you
were not on their airway when you should have been.





The problem with VORs is that they are not aligned with magnetic north.
Usually, they are aligned with magnetic north when the VOR station is
first
installed, but they are not kept in alignment as the earth's magnetic
field
shifts. Have you ever noticed how runways are occasionally recharted with
new magnetic headings? Also check he
http://www.geolab.nrcan.gc.ca/geomag...vt_nmp_e.shtml.

Many GPS receivers use a model of the earth's magnetic field that results
in
a magnetic correction similar to the isogonic lines on the chart. If the
instructor executed a direct to the VOR waypoint in the GPS and then used
the OBS feature to select the inbound course as depicted by the VOR radial
on the chart, he may be several degrees off.

If you want to look at an example, go to www.airnav.com and pull up SWL
VOR
and KOXB (Ocean City). SWL has a variation of 8W (1965) and KOXB has a
variation of 12W (2000). There might be a close airport, but SWL is 22 nm
from KOXB.

Some GPS receivers such as the Garmin 196, 295, 296, 430, and 530 use the
slaved value of the VOR for the OBS mode. Thus, setting the OBS mode to a
value results in the same path over the ground as if you selected the VOR
OBS to the same number. On some GPS receivers, such as the Garmin GPS III
Pilot the GPS does not compensate for this VOR misalignment.

What I don't know is whether there is any requirement for an IFR certified
GPS to use the VOR slaved value for magnetic variation. There is also the
possibility that the instructor in your story was using a non-IFR GPS.

This is not to say the OBS mode is the best way to navigate an airway,
just
that this might be a cause for error. A better way is to set up a route
in
the GPS to reflect points on the airway. Such as from VOR A to VOR B or
INTERSECTION to VOR if there is a bend in the airway.

John Bell
www.cockpitgps.com

Most do not. The ONLY panel mount Garmin that has airways is the CNX-80.

Karl
Biding my time in Roskilde, Denmark
"C J Campbell" wrote in message
...

"Bob Gardner" wrote in message
...
An article (actually, a sidebar to an article) in the July IFR magazine
says
"According to AIM 1-1-20 (f)(7), by omission, you can't just input the
VOR
as the active waypoint....," and "...according to this passage, the FAA
allows GPS to substitute for everything except for a VOR. For some
reason,
the FAA has faith in its VORs and won't let you substitute GPS for them
as
a
primary means of navigation."

Maybe this is why Garmin does not include VOR-based airways.


Garmin panel mount units have airways.

More likely the reason airways are not included in the handhelds is the
limitation on memory for the database.