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.