GPS clearance puzzle

Thanks, John.


"John R. Copeland" wrote in message
...
From page 37 of the GNS 480 Pilot's Guide;
"NOTE: When using the OBS mode with a VOR station, the GNS 480
will use the station declination of the VOR.
For other waypoints, the GNS 480 will use magnetic variation based on
your present position."

In my opinion, it should use VOR station declination *only* in OBS
mode, but in Salem they chose to use it in all modes involving VORs.
That wasn't their original choice, but the UPS pilots wanted it that way.
---JRC---

"Stan Prevost" wrote in message
...
Roy, just curious, does the CNX-80 use the facility magnetic variation
when
setting up a VOR radial in OBS mode? I believe the Apollo GX-60 does not.
I think the 430/530 does use the facility variation, and I wonder if
Garmin
changed what the Apollo units do, either in the CNX-80 or going to the
GNS-480.

There is a four degree difference between facility variation and actual
variation at our local VOR. It would make two miles of crosstrack error
at
30 miles from the VOR, usually not a big deal, but worth knowing about.

Stan

"Roy Smith" wrote in message
...
Apparently, if you file IFR HPN - MMU, you get a clearance which starts
"CMK CMK275R SAX039R SAX" (i.e. fly outbound on the CMK 275 until you
intercept the SAX 039, then fly that inbound to SAX). In the good old
days of 2 VOR receivers, this is trivial to fly; the radios don't know
or care that the cross-radial fix you're going to doesn't have a name.
But, how would you fly that with a GPS?

I've been puzzling over that one for a week or so now, and the best I
can come up with is to use the GPS's OBS mode to track outbound on the
CMK 275, and set up a VOR receiver to indicate the crossing radial.

Can anybody figure out a way to set it up purely on the GPS? I'm using
a CNX-80, but it might be interesting to see how other units would do it
too.

"Stan Prevost" wrote:
Roy, just curious, does the CNX-80 use the facility magnetic variation when
setting up a VOR radial in OBS mode?

According to the CNX-80 manual, facility variation is used in OBS mode
when the waypoint is a VOR, but not in Course-To or Course-From mode
(and not in OBS mode when the waypoint is not a VOR).

All things considered, I think that makes a lot of sense.

I believe the Apollo GX-60 does not.

I just looked at the GX-60 manual, in the section on OBS mode. It
doesn't say one way or the other, which I assume means it does not take
variation into account.

"Roy Smith" wrote in message =
...
"Stan Prevost" wrote:
Roy, just curious, does the CNX-80 use the facility magnetic =
variation when=20
setting up a VOR radial in OBS mode?
=20
According to the CNX-80 manual, facility variation is used in OBS mode =

when the waypoint is a VOR, but not in Course-To or Course-From mode=20
(and not in OBS mode when the waypoint is not a VOR).
=20
All things considered, I think that makes a lot of sense.
=20
I believe the Apollo GX-60 does not.
=20
I just looked at the GX-60 manual, in the section on OBS mode. It=20
doesn't say one way or the other, which I assume means it does not =
take=20
variation into account.

Roy:
I've never yet used the CNX 80 "Course To" or "Course From" in flight,
but the GNS 480 Windows Simulator appears to me that it uses
VOR station declination for those modes, as well as all other modes
whenever VORs are involved as waypoints.
---JRC---

"Roy Smith" wrote in message
...

I just looked at the GX-60 manual, in the section on OBS mode. It
doesn't say one way or the other, which I assume means it does not take
variation into account.

The manual shows what data is included in the database for a VOR, and it
does not include facility variation.

CMK CMK275R SAX039R SAX

Hmmmm...does it appear this way on a flight progress strip? Duats
won't accept that sort of thing.

Greg Esres wrote:
CMK CMK275R SAX039R SAX

Hmmmm...does it appear this way on a flight progress strip? Duats
won't accept that sort of thing.

A flight progress strip would have a radial and DME.

"Greg Esres" wrote in message
...
CMK CMK275R SAX039R SAX

Hmmmm...does it appear this way on a flight progress strip? Duats
won't accept that sort of thing.


For ATC Flight Data processing the input would be CMK.CMK275..SAX039.SAX, it
appears on the strip without the dots.

On Thu, 02 Dec 2004 04:11:34 GMT, Greg Esres
wrote:

CMK CMK275R SAX039R SAX

Hmmmm...does it appear this way on a flight progress strip? Duats
won't accept that sort of thing.


It will if you use distance, e.g., CMK275023, the last three digits
being the distance from Carmel on the 275 until you intercept the
039.

You just need to measure the distance, or play with the planner and
maybe do a binary search along the 275R until you get the 039R to
SAX.

In article ,
"Stan Prevost" wrote:

"Roy Smith" wrote in message
...

I just looked at the GX-60 manual, in the section on OBS mode. It
doesn't say one way or the other, which I assume means it does not take
variation into account.

The manual shows what data is included in the database for a VOR, and it
does not include facility variation.

That would be another good clue that it doesn't use it :-)

On Thu, 02 Dec 2004 12:43:01 GMT, wrote:

On Thu, 02 Dec 2004 04:11:34 GMT, Greg Esres
wrote:

CMK CMK275R SAX039R SAX

Hmmmm...does it appear this way on a flight progress strip? Duats
won't accept that sort of thing.


It will if you use distance, e.g., CMK275023, the last three digits
being the distance from Carmel on the 275 until you intercept the
039.

You just need to measure the distance, or play with the planner and
maybe do a binary search along the 275R until you get the 039R to
SAX.


By the way, once you have the correct distance, DUATS will show the
lat/lon of the junction, which will give Roy a way to enter the
junction into the GPS as a waypoint.