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GTN650 VNAV problem...

jeffkersey

jeffkersey

Well Known Member
I have a Garmin GTN650 V.6.50. Sometimes when using the VNAV tool, when I put in an along track offset, it will not allow it? If I pull out the offset, it will give me the VNAV to the waypoint itself. Sometimes it gives me the offset as it should.
Anyone else run into this or know why it might be doing this?
 
Garmin has a forum coming up (April 30) on the GTN650 and VNAV. I, too, have had problems with the VNAV. The easy solution (VFR) is to switch your nav source to the G3X Touch (the flight plan will already be transferred from the GTN) and use the G3X VNAV to the destination.

Register for the webinar at https://www.garmin.com/en-US/aviation/webinars/

Sometimes I almost feel like I work for them...
 
No G3X...

Ed_Wischmeyer said:
Garmin has a forum coming up (April 30) on the GTN650 and VNAV. I, too, have had problems with the VNAV. The easy solution (VFR) is to switch your nav source to the G3X Touch (the flight plan will already be transferred from the GTN) and use the G3X VNAV to the destination.

Register for the webinar at https://www.garmin.com/en-US/aviation/webinars/

Sometimes I almost feel like I work for them...
Click to expand...

I wish I had G3X but not willing to spend the money right now. I have old school Dynon EFIS's. No synthetic vision.... I like to use the VSR to calculated my decent. Sometimes it works as it should, and sometimes it will only let me set the arrival altitude at the actual waypoint and not at an offset. Also, it seems I should be able to set the offset to "after" a waypoint, but the "before" button is greyed out and I cannot change it.

Thanks for the webinar link :)

Blue Skies - JK
 
GTN 650 VNAV

jeffkersey said:
I have a Garmin GTN650 V.6.50. Sometimes when using the VNAV tool, when I put in an along track offset, it will not allow it? If I pull out the offset, it will give me the VNAV to the waypoint itself. Sometimes it gives me the offset as it should.
Anyone else run into this or know why it might be doing this?
Click to expand...

Jeff,

If you could email us an example of a flight plan with a VNAV descent you are looking to fly, we can replicate it and see if we find any issues with it, or point you in the right direction on the 'button-ology' side of things. There are no known issues with VNAV on the GTN at this time.

Thanks,

Justin
 
Flight plan example..

g3xpert said:
Jeff,

If you could email us an example of a flight plan with a VNAV descent you are looking to fly, we can replicate it and see if we find any issues with it, or point you in the right direction on the 'button-ology' side of things. There are no known issues with VNAV on the GTN at this time.

Thanks,

Justin
Click to expand...

Justin,

The last time it happened was last week flying from a private strip north of NASHVILLE TN to KFFC. While at 7000ft, still over TN, I was demonstrating the VNAV feature to a pilot that was flying with me. I select the ALT field next to the KFFC waypoint in the flight plane and set it to be 2000ft 3 mile before KFFC. When I hit save, it says it cannot do it. If I delete the 3 mile offset it saves just fine. Sometimes it works as it should. Sometimes it does not. I tried this on the iPad trainer and had no issues.

Another question, why can’t I set an alt restriction to a distance after a particular waypoint? The “Mode” field says “before” and is grayed out and cannot be changed.

Thanks for your help,

Jeff
 
Last edited:
VNAV Descent

jeffkersey said:
Justin,

The last time it happened was last week flying from a private strip north of NASHVILLE TN to KFFC. While at 7000ft, still over TN, I was demonstrating the VNAV feature to a pilot that was flying with me. I select the ALT field next to the KFFC waypoint in the flight plane and set it to be 2000ft 3 mile before KFFC. When I hit save, it says it cannot do it. If I delete the 3 mile offset it saves just fine. Sometimes it works as it should. Sometimes it does not. I tried this on the iPad trainer and had no issues.

Another question, why can?t I set an alt restriction to a distance after a particular waypoint? The ?Mode? field says ?before? and is grayed out and cannot be changed.

Thanks for your help,

Jeff
Click to expand...

Jeff,

There are several reasons VNAV functions can be limited. For instance, the altitude constraint will be invalidated if the profile you program into the unit puts the TOD behind your current position.

Do you have a datalog from the flight? That would be helpful in getting a better idea of what the flight plan looked like. The flight plan as entered in the GTN would be helpful, as well as where you were located when you were trying to enter the VNAV profile.

There are some settings we may want to look at on the GTN in addition to the above information, it may be easier to email us at [email protected] to sort this out.

Thanks,

Justin
 
pictures..

g3xpert said:
Jeff,

There are several reasons VNAV functions can be limited. For instance, the altitude constraint will be invalidated if the profile you program into the unit puts the TOD behind your current position.

Do you have a datalog from the flight? That would be helpful in getting a better idea of what the flight plan looked like. The flight plan as entered in the GTN would be helpful, as well as where you were located when you were trying to enter the VNAV profile.

There are some settings we may want to look at on the GTN in addition to the above information, it may be easier to email us at [email protected] to sort this out.

Thanks,

I took these pictures last week. I was trying to make an offset for RTZ and got the message show in the picture. I removed the offset and it calculated the VNAV data to RTZ just fine. Strange. I sat in on a Garmin VNAV webinar on Thursday and posed the question there. They asked me to send pictures and a description of the account, I did, no response. So, I thought I'd try here.

On my flights this past Saturday, I was able to create an offset each time I wanted to with no issues. Very strange. Seems to be no rhyme or reason I can see...

Thanks for any help you can give..

IMG_7698.jpeg


IMG_7700.jpeg


IMG_7697.jpeg


IMG_7701.jpeg
Click to expand...
 
See on the bottom row of GPS annunciations it says ?VLOC? in green? Try changing that GPS CDI source to read ?GPS? and try the ATK VNAV again.
 
also interesting

I.am.Human.Factors said:
See on the bottom row of GPS annunciations it says ?VLOC? in green? Try changing that GPS CDI source to read ?GPS? and try the ATK VNAV again.
Click to expand...

Yes I saw that but the auto pilot was tracking the gps. Very strange... I'll try that next time I am up to see if that makes a difference. It does not make sense that all I do is remove the offset and it works to the waypoint? Even when it is still showing Vloc.
 
VNAV Descent Issues

jeffkersey said:
Yes I saw that but the auto pilot was tracking the gps. Very strange... I'll try that next time I am up to see if that makes a difference. It does not make sense that all I do is remove the offset and it works to the waypoint? Even when it is still showing Vloc.
Click to expand...

Jeff,

I am not sure how it would work with other EFIS displays, but if your CDI is displayed as VLOC on the GTN, you will have green needles on the HSI meaning you are looking at guidance from a VOR. The only way you would be tracking GPS with a G3X in this case is if you were navigating with the GPS Internal to the EFIS.

Please reach out to us via email to address the VNAV issue, there are just too many questions and configuration settings, it will be best to address via email.

Thanks,

Justin
 
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