GTN 750 Holding

Bill Crawford

Bill Crawford

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Does anyone know where to find in the Garmin GTN 750 Pilot’s Guide manual information about holding patterns? I can only find one reference for holding patterns in the Index, and that is only for flying an approach with a hold in it. What am I missing? Thanks!
 

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See section 4.2.3 for holding at a waypoint that's in your flight plan, or section 5.8 for going direct to a user defined hold.
 
Thanks for the reply. I don’t have either of those sections you cited. The last section in chapter 4 is 4.2.2
The last section I have of chapter 5 is 5.8.
My Pilot’s Guide is Revision “H” which came with my newly acquired airplane. I will see how up to date that revision is. It may have been re-indexed.
 
Bill Crawford said:
Thanks for the reply. I don’t have either of those sections you cited. The last section in chapter 4 is 4.2.2
The last section I have of chapter 5 is 5.8.
My Pilot’s Guide is Revision “H” which came with my newly acquired airplane. I will see how up to date that revision is. It may have been re-indexed.
Click to expand...
Actually meant to say that my book goes to 4.2.2, then right into 4.3
There is no 5.8, it goes to 5.7, then right into 6.0
 
Bill Crawford said:
Thanks for the reply. I don’t have either of those sections you cited. The last section in chapter 4 is 4.2.2
The last section I have of chapter 5 is 5.8.
My Pilot’s Guide is Revision “H” which came with my newly acquired airplane. I will see how up to date that revision is. It may have been re-indexed.
Click to expand...
Pilot Guides get revised when software gets updated. It’s less about “re-indexing” than added functionality. As @flyingcheesehead said, latest is R, but I think this functionality was first discussed in Revision J.
Let'sgoflying! said:
I think this is still what happens even if the video is years old

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It is. I also wrote about them in IFR Magazine - Random Holds (no paywall on this one)
 
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Thanks all! I’ve been referencing the paper version I got from the previous owner. I will try to get an updated one. I have a downloaded version too, so I’ll check it out as well.
 
midlifeflyer said:
It is. I also wrote about them in IFR Magazine - Random Holds (no paywall on this one)
Click to expand...
Should one adjust for VOR station declination since the GTN is executing the hold by GPS? I tried to figure it out using the GTN trainer but got a little dizzy. The LIB VOR is shown with a 3W declination. The sectional in that area shows a 9W variation. The GTN trainer's preview of the hold shows an course of 220 outbound directly on the 220 radial of the compass rose for LIB. So at least one of the following must be true:

1. The GTN shows VOR compass roses aligned with true north
2. The GTN adjusts holds on VORs to match radials
3. The GTN trainer has a database of VOR declinations but ignores them and rotates all VORs to match true north
4. I am forgetting how to deal with VOR station declination
 
iamtheari said:
Should one adjust for VOR station declination since the GTN is executing the hold by GPS? I tried to figure it out using the GTN trainer but got a little dizzy. The LIB VOR is shown with a 3W declination. The sectional in that area shows a 9W variation. The GTN trainer's preview of the hold shows an course of 220 outbound directly on the 220 radial of the compass rose for LIB. So at least one of the following must be true:

1. The GTN shows VOR compass roses aligned with true north
2. The GTN adjusts holds on VORs to match radials
3. The GTN trainer has a database of VOR declinations but ignores them and rotates all VORs to match true north
4. I am forgetting how to deal with VOR station declination
Click to expand...
So, for every random hold, you are going to look up the last time the VOR was aligned to magnetic, pull up the sectional (or check the AFD) and adjust for the (6° in this case) difference? Are you also going to account for the fact that if you did the hold using VOR, you might be up to 6°(or is that 8) off?

I’m not sure which of those statements, if any, are true (@John Collins probably does) but I don’t worry about it. I don’t want to get dizzy.

Funny, I have a video of intercepting an assigned radial using GPS where someone insisted it was illegal to do that because of declination.
 
If the hold fix is the VOR, then the GTN will use the VOR declination, IOW you will be guided to perform the hold on a VOR radial. If the hold is along an airway and at a fix other than a VOR, then the GTN will use the current magnetic variation, and you will see the 6 degree angle between the radial and the hold inbound course. You can see this if you enter this route in the GTN "GIZMO V454 LIB. If you insert a hold at LIB 076 inbound, it will depict with the inbound course along the airway 256 radial. If you place a hold at GIZMO 256 Inbound, it will show the 6 degree angle and will not lie along the radial. This is because the TSO C145/146 navigator requires that the GPS use the declination when the active fix is a VOR, otherwise it uses the current magnetic variation. This supports tracking along a VOR radial when navigating to a VOR or either to/from a VOR when using OBS mode. Although the course will use the VOR radial if the VOR is the active fix, the GPS track will use the current magnetic variation, so the track to keep the CDI centered will be 6 degrees off (no wind). Of course, most pilots could care less or just aren't aware of this, so they may think they are fighting a crosswind to account for the difference. I also believe that even the 6 degree difference will stay well within the protected area for a hold.
 
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John Collins said:
If the hold fix is the VOR, then the GTN will use the VOR declination, IOW you will be guided to perform the hold on a VOR radial. If the hold is along an airway and at a fix other than a VOR, then the GTN will use the current magnetic variation, and you will see the 6 degree angle between the radial and the hold inbound course. You can see this if you enter this route in the GTN "GIZMO V454 LIB. If you insert a hold at LIB 076 inbound, it will depict with the inbound course along the airway 256 radial. If you place a hold at GIZMO 256 Inbound, it will show the 6 degree angle and will not lie along the radial. This is because the TSO C145/146 navigator requires that the GPS use the declination when the active fix is a VOR, otherwise it uses the current magnetic variation. This supports tracking along a VOR radial when navigating to a VOR or either to/from a VOR when using OBS mode. although the course will use the VOR radial if the VOR is the active fix, the GPS track will use the current magnetic variation, so the track to keep the CDI centered will be 6 degrees off (no wind). Of course, most pilots could care less or just aren't aware of this, so they may think they are fighting a crosswind to account for the difference. I also believe that even the 6 degree difference will stay well within the protected area for a hold.
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I figured you’d know it, John.
 
Highly recommend you download the free Garmin GTN trainer software / apps and you can play with it at will on your computer or tablet. If you have MS Flight Sim you can also get the 750 trainer working 'live' in a number of different addons. You can practice a lot scenarios that way much cheaper than trying to fly them IRL.
 
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