Disappearing course line on GNS430

bcool

bcool

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St Charles, MO
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Bud
I had something happen to me on a flight yesterday that's happened once before, too, and I was wondering if anyone might know what was going on....

I was bopping along, direct to my destination (1H0), dutifully following the magenta line :)

I was approaching the St. Louis Class B, and I was using Flight Following. The controller told me to proceed direct to the Cardinal VOR (CSX), so I did a direct-to CSX and tracked that course.

After I passed CSX, I was within maybe 5 miles of 1H0, and for grins I did a direct-to for 1H0. I had a visual on the field but I did it anyway in case ATC would have vectored me around and I lost sight of it.

After a minute or so the magenta line disappeared off the 430. I thought "what the?" so I did a direct-to again. After I hit the final Enter to activate it, the start of the magenta line was a ways beyond my aircraft position - not right on it like usual. After a second or two it redrew the line with it starting at my position. Weird!

This has happened to me before, again when I was fairly close to my destination (losing the magenta line, that is).

Has this ever happened to anyone here, or could I be doing something wrong to cause it? :confused:
 
Did you get the "loss of GPS position" message, even momentarily?
 
I'm guessing your fight path was at a significant angle off the straight line to the newly designated destination point, and your range scale was pretty short. Note that when you hit D->, it computes the turn radius and then draws the new magenta line starting at the end of the turn, not starting where you are and including the turn. Further, unlike turns in FPL mode, it doesn't show the dashed turn arc line leading to the new course line. Put those things together, and you could see a gap of a couple of miles from where you are to the beginning of the line, and if you're in a very short range display, the beginning of the new magenta line could be off the screen in the direction of the turn.
 
Ron, that sounds reasonable for the new line being offset.

Still not sure about the disappearing course line. I didn't notice a loss of signal message - if it was a brief loss, would the message go away as soon as service was restored? If that's the case, I might have missed it if it was of short duration.

If I did lose the signal temporarily, would the direct-to course be dropped from the 430, or should it have been restored as soon as the signal came back?
 
bcool said:
Ron, that sounds reasonable for the new line being offset.

Still not sure about the disappearing course line. I didn't notice a loss of signal message - if it was a brief loss, would the message go away as soon as service was restored? If that's the case, I might have missed it if it was of short duration.
Click to expand...
bcool said:
If I did lose the signal temporarily, would the direct-to course be dropped from the 430, or should it have been restored as soon as the signal came back?
Click to expand...
If you lost the signal while navigating with the line in front of you, you'd get a whole bunch of very obvious warnings in the middle of the screen as the system degraded to DR mode, but the magenta line would remain once you cleared those warnings. So, I'm stumped on why the line stretching in front of you would suddenly disappear without warning and without you making an input.
 
Ron Levy said:
I'm guessing your fight path was at a significant angle off the straight line to the newly designated destination point, and your range scale was pretty short. Note that when you hit D->, it computes the turn radius and then draws the new magenta line starting at the end of the turn, not starting where you are and including the turn. Further, unlike turns in FPL mode, it doesn't show the dashed turn arc line leading to the new course line. Put those things together, and you could see a gap of a couple of miles from where you are to the beginning of the line, and if you're in a very short range display, the beginning of the new magenta line could be off the screen in the direction of the turn.
Click to expand...

The new GTN650/750 has updated the display software and will show the curved line of the turn radius and resulting straight line to the next fix.

I was established in hold at a VOR and selected/activated a GPS approach. The initial fix was behind me in the holding pattern and the 750 displayed the turn to get to the fix.
 
BillTIZ said:
The new GTN650/750 has updated the display software and will show the curved line of the turn radius and resulting straight line to the next fix.

I was established in hold at a VOR and selected/activated a GPS approach. The initial fix was behind me in the holding pattern and the 750 displayed the turn to get to the fix.
Click to expand...
Correct, but I personally don't think this feature alone would be worth the cost for the OP to replace his 430 with a 650.
 
Ron Levy said:
Correct, but I personally don't think this feature alone would be worth the cost for the OP to replace his 430 with a 650.
Click to expand...

Agreed!
The owner was upgrading from a KLN-89B with a failing display, he needed a WAAS system.
Plus he got a discount from an installer who needed to meet a quota to keep his Garmin franchise.
 
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