CNX-80 "discontinuity"

[Roy Smith]

When you put a flight plan into the CNX-80, you end up with a
"discontinuity" before the last fix. My habit is to delete the
discontinuity as soon as I finish entering the route. Another
instructor in my club teaches that you should NOT delete the
discontinuity.

I can't see any strong arguments one way or the other. Leaving it in
doesn't seem to hurt anything (except that you get a warning when you
finally arrive at your destination). Taking it out doesn't seem to hurt
anything either.

Can anybody think of any real reason to either insist that it be deleted
or insist that it NOT be deleted?

[John R. Copeland]

"Roy Smith" > wrote in message =
...
> When you put a flight plan into the CNX-80, you end up with a=20
> "discontinuity" before the last fix. My habit is to delete the=20
> discontinuity as soon as I finish entering the route. Another=20
> instructor in my club teaches that you should NOT delete the=20
> discontinuity.
>=20
> I can't see any strong arguments one way or the other. Leaving it in=20
> doesn't seem to hurt anything (except that you get a warning when you=20
> finally arrive at your destination). Taking it out doesn't seem to =
hurt=20
> anything either.
>=20
> Can anybody think of any real reason to either insist that it be =
deleted=20
> or insist that it NOT be deleted?

I always delete the discontinuity so as to have a complete flight plan.
Otherwise, the CNX 80 enters Suspend Mode at the discontinuity.
To me, that's a strong argument for removing the discontinuity.
I'd be interested in hearing the other guy's reasons for retaining it.

Of course, the discontinuity will disappear automatically
if an approach is selected at the destination,
but I don't see that as a reason to leave the discontinuity in place.
In case of a visual approach, I normally want navigation to the airport.
---JRC---

[Steven DalPra]

Stop thinking of the CNX 80 as a moving map GPS but as an FMS. Then keep
the discontinuity in until you have received the ATIS update as to active
approaches and runways. This makes selecting an approach easier as you use
the existing FPL and do not have to extensively modify the current one.
Last month a pilot at my airport replaced a new CNX 80 with a GNS 430. His
needs were to fly "direct" and not use airways in his flight planning. He
was comfortable with a more popular and "intuitive" unit. He was unhappy
that the compromise involved giving up GPSS roll steering with his
autopilot.


"Roy Smith" > wrote in message
...
> When you put a flight plan into the CNX-80, you end up with a
> "discontinuity" before the last fix. My habit is to delete the
> discontinuity as soon as I finish entering the route. Another
> instructor in my club teaches that you should NOT delete the
> discontinuity.
>
> I can't see any strong arguments one way or the other. Leaving it in
> doesn't seem to hurt anything (except that you get a warning when you
> finally arrive at your destination). Taking it out doesn't seem to hurt
> anything either.
>
> Can anybody think of any real reason to either insist that it be deleted
> or insist that it NOT be deleted?

[Roy Smith]

In article >,
"Steven DalPra" > wrote:

> Stop thinking of the CNX 80 as a moving map GPS but as an FMS. Then keep
> the discontinuity in until you have received the ATIS update as to active
> approaches and runways. This makes selecting an approach easier as you use
> the existing FPL and do not have to extensively modify the current one.

Why is it easier to enter an approach if you leave the discontinuity in?
In either case, you need to hit PROC (possibly having to hit FN first,
if the PROC softkey is not showing), select the approach, select the IAF
(or Vectors), hit EXEC, and then hit ENTER to confirm over-writing the
active flight plan. I hope I got all that right :-)

How does this process change if you leave the discontinuity in or take
it out?

[Maik]

Steven DalPra wrote:

> Last month a pilot at my airport replaced a new CNX 80 with a GNS 430. His
> needs were to fly "direct" and not use airways in his flight planning. He
> was comfortable with a more popular and "intuitive" unit. He was unhappy
> that the compromise involved giving up GPSS roll steering with his
> autopilot.

The CNX80 has GPSS roll steering included?

Maik

[Steven DalPra]

It has the ability to accept roll steering from a capable autopilot. Talk
to your avionics tech for details. Also, their is an add-on for analog
autopilots to allow them to accept from some older units.
"Maik" > wrote in message
...
>
>
> Steven DalPra wrote:
>
>> Last month a pilot at my airport replaced a new CNX 80 with a GNS 430.
>> His needs were to fly "direct" and not use airways in his flight
>> planning. He was comfortable with a more popular and "intuitive" unit.
>> He was unhappy that the compromise involved giving up GPSS roll steering
>> with his autopilot.
>
> The CNX80 has GPSS roll steering included?
>
> Maik

[Maik]

Hmm... until now the only autopilot with GPSS I found are from S-TEC.
Also the extra GPSS box from S-TEC is only for S-TEC autopilots... at
least it is only aloud with S-TEC :-)

Do you have a link, name or partnumber so I could search for and read a
bit more...?

And normally the GPS is controlling the GPSS and not the vice versa.
Are you sure?

Maik

Steven DalPra wrote:

> It has the ability to accept roll steering from a capable autopilot. Talk
> to your avionics tech for details. Also, their is an add-on for analog
> autopilots to allow them to accept from some older units.
> "Maik" > wrote in message
> ...
>
>>
>>Steven DalPra wrote:
>>
>>
>>>Last month a pilot at my airport replaced a new CNX 80 with a GNS 430.
>>>His needs were to fly "direct" and not use airways in his flight
>>>planning. He was comfortable with a more popular and "intuitive" unit.
>>>He was unhappy that the compromise involved giving up GPSS roll steering
>>>with his autopilot.
>>
>>The CNX80 has GPSS roll steering included?
>>
>>Maik
>
>
>

[Peter Clark]

On Thu, 16 Sep 2004 22:16:56 +0200, Maik > wrote:

>Hmm... until now the only autopilot with GPSS I found are from S-TEC.
>Also the extra GPSS box from S-TEC is only for S-TEC autopilots... at
>least it is only aloud with S-TEC :-)

The newer Bendix KLN94 (the ones with the part number ending in -0102)
have GPSS out to the KAP140 autopilot.

>Do you have a link, name or partnumber so I could search for and read a
>bit more...?
>
>And normally the GPS is controlling the GPSS and not the vice versa.
>Are you sure?

At least on the King ones that's the way I understand it to work -
GPSS sends out roll commands which the autopilot acts on.

[john smith]

What is GPSS?

[Maik]

Take a look at the publications from S-Tec

http://www.s-tec.com/prodbrochures.html

maik

john smith wrote:
> What is GPSS?
>

[Maik]

Peter Clark wrote:

> On Thu, 16 Sep 2004 22:16:56 +0200, Maik > wrote:
>
>
>>Hmm... until now the only autopilot with GPSS I found are from S-TEC.
>>Also the extra GPSS box from S-TEC is only for S-TEC autopilots... at
>>least it is only aloud with S-TEC :-)
>
>
> The newer Bendix KLN94 (the ones with the part number ending in -0102)
> have GPSS out to the KAP140 autopilot.

Good to know. We just got a new Cessna with those parts in our flying
club. I will try it out.


>>Do you have a link, name or partnumber so I could search for and read a
>>bit more...?
>>
>>And normally the GPS is controlling the GPSS and not the vice versa.
>>Are you sure?
>
>
> At least on the King ones that's the way I understand it to work -
> GPSS sends out roll commands which the autopilot acts on.

Yes, thats the way it works.

Until now, I couldn't find any info about GPSS steering out of the
CNX80.

Maik

[Ron Rosenfeld]

On Thu, 16 Sep 2004 11:01:55 -0400, "Steven DalPra"
> wrote:

>Then keep
>the discontinuity in until you have received the ATIS update as to active
>approaches and runways. This makes selecting an approach easier

I have noted that on my CNX80, if I leave in the discontinuity, the
calculated time to destination (one of the optional items one can put on
the screen) is inaccurate by a significant amount.


--ron

[Scott Skylane]

O.K.,

I give up. What the heck is this "Discontinuity"?! Is it an extra
waypoint created by the box? If so, where is it in relation to the
flight plan? What is it's function?? I've used many different makes of
GPS, both IFR and VFR, but have never come across this "thing". Thanks!

Happy Flying!
Scott Skylane

[Roy Smith]

In article >,
Scott Skylane > wrote:

> O.K.,
>
> I give up. What the heck is this "Discontinuity"?! Is it an extra
> waypoint created by the box? If so, where is it in relation to the
> flight plan? What is it's function?? I've used many different makes of
> GPS, both IFR and VFR, but have never come across this "thing". Thanks!
>
> Happy Flying!
> Scott Skylane

On the CNX-80, routes are made up of waypoints connected by legs. A
discontinuity is what you get when you have a pair of adjacent
waypoints, but you haven't told it how to get from one to the other.

So, if I were to put in:

Origin: KHPN
Destination: KIJD

I would end up with a flight plan that had two waypoints (KHPN and
KIJD), and a discontinuity connecting them. In the units you're used to
using, the flight plan software would have probably just invented a
"direct" leg between those two points, but the CNX-80 doesn't do that.

It's sort of a place-holder for you to fill in more information. In the
case of the KHPN-KIJD flightplan, my clearance was "vectors CMK, V3,
HFD, direct". So, I'd add a CMK waypoint, then, I'd add an airway
segment. I'd get a menu of airways which depart CMK, and I'd select V3
from the menu. Then I'd get a menu of fixes along V3, and I'd scroll
through them to find HFD. When I was done with that, I'd have a flight
plan that looked like:

KHPN
bearing xxx, distance yy.y
CMK
V3
HFD
discontinuity
KIJD

or something like that. I may have messed up on the details a bit, but
that's pretty much the format it's displayed in.

Anyway, if I left it like this and took off, everything would be fine
until a few miles before HFD, when it would start giving me warning
messages about "approaching discontinuity". If I ignore the warnings,
when it gets to HFD, it will (IIRC) go into suspend mode and stop
navigating.

If I clear the discontinuity, it'll insert a "direct to" leg, and I'll
end up with:

KHPN
bearing xxx, distance yy.y
CMK
V3
HFD
bearing xxx, distance yy.y
KIJD

My understanding is that this is how the FMS's the big boys fly with
have always operated.

If you think about how ATC reads clearances to you, it sort of makes
sense. Clearance Delivery read my clearance "cleared to KIJD, via radar
vectors CMK, V1, HFD, direct". If he hadn't said "direct" at the end, I
wouldn't know how to get from HFD to KIJD. Clearing the discontinuity
when you enter the flight plan is essentially programming the "direct"
part.

[Scott Skylane]

Roy Smith wrote:
> In article >,
> Scott Skylane > wrote:
>
>
>>O.K.,
>>
>>I give up. What the heck is this "Discontinuity"?! Is it an extra
>>waypoint created by the box? If so, where is it in relation to the
>>flight plan? What is it's function?? I've used many different makes of
>>GPS, both IFR and VFR, but have never come across this "thing". Thanks!
>>
>>Happy Flying!
>>Scott Skylane
>
>
> On the CNX-80, routes are made up of waypoints connected by legs. A
> discontinuity is what you get when you have a pair of adjacent
> waypoints, but you haven't told it how to get from one to the other.
/snip/

Thanks, Roy,

That clears it up!

Happy Flying!
Scott Skylane

[Steven DalPra]

Please check out Garmin`s site and download the free manual. It covers some
of the basics but the really good stuff is not here.
"Scott Skylane" > wrote in message
...
> Roy Smith wrote:
>> In article >,
>> Scott Skylane > wrote:
>>
>>
>>>O.K.,
>>>
>>>I give up. What the heck is this "Discontinuity"?! Is it an extra
>>>waypoint created by the box? If so, where is it in relation to the
>>>flight plan? What is it's function?? I've used many different makes of
>>>GPS, both IFR and VFR, but have never come across this "thing". Thanks!
>>>
>>>Happy Flying!
>>>Scott Skylane
>>
>>
>> On the CNX-80, routes are made up of waypoints connected by legs. A
>> discontinuity is what you get when you have a pair of adjacent waypoints,
>> but you haven't told it how to get from one to the other.
> /snip/
>
> Thanks, Roy,
>
> That clears it up!
>
> Happy Flying!
> Scott Skylane
>