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  #1  
Old 01-22-2020, 08:25 AM
von_flyer von_flyer is offline
 
Join Date: Oct 2014
Location: Metamora, Michigan
Posts: 182
Default Garmin GTX335 ALT MODE - self select

Does anyone have their GTX335 transponder setup so that:

1. You power up by selecting STBY MODE.
2. It switches to ALT MODE automatically based on GPS data showing take-off speed.

???

My GTX330 was configured to do this but I cannot see how to do it with the 335.
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  #2  
Old 01-22-2020, 10:23 AM
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bhester bhester is offline
 
Join Date: Jan 2005
Location: Hopkinsville, KY
Posts: 903
Default Not no more

Years ago that is how it was done. You were suppose to turn your transponder to STBY when on the ground. Not any more. You are suppose to keep your transponder on ALT all the time. I don't remember exactly when that changed. With ADSB you will automatically show up as a brown icon to other people, meaning you are on the ground when you are on the ground and you will change to a white icon when you are airborne. That is one reason there is no longer a STBY.
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Last edited by bhester : 01-22-2020 at 10:26 AM.
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  #3  
Old 01-22-2020, 10:46 AM
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g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
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Default GTX 335 Air/Ground Sense Logic

Quote:
Originally Posted by von_flyer View Post
Does anyone have their GTX335 transponder setup so that:

1. You power up by selecting STBY MODE.
2. It switches to ALT MODE automatically based on GPS data showing take-off speed.

???

My GTX330 was configured to do this but I cannot see how to do it with the 335.
Good Morning,

You should be able to power on the GTX 335 using the ON, SBY, or ALT buttons.

You will want to always use ALT mode while in the air and on the ground, unless otherwise requested by ATC. All air/ground state transmissions are handled internally by the GTX 335, using a variety of factors, including GPS ground speed.

Are you having an issue with these two items? The software has been updated in the past to improve air/ground sense logic. What software is your transponder currently running?

Thanks,

Justin
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  #4  
Old 01-22-2020, 12:13 PM
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Jvon811 Jvon811 is offline
 
Join Date: Mar 2014
Location: Fenton, MI (based FNT)
Posts: 115
Default

I think the OP is asking about automatic switching...

I fire up my GTX327 with the STBY button and it will then automatically go to ALT mode, on takeoff, once it's above a certain groundspeed or PA or something, I can't remember what triggers it.

How do you make the 335 do that also? I've flown the airplane in question, you have to manually engage ALT before takeoff or it never will. Then ATC asked the embarrassing question "Do you have your transponder on?" I forget everytime I fly that airplane...
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Last edited by Jvon811 : 01-22-2020 at 12:16 PM. Reason: phrasing...
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  #5  
Old 01-22-2020, 02:01 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,160
Default

Quote:
Originally Posted by Jvon811 View Post
I think the OP is asking about automatic switching...

I fire up my GTX327 with the STBY button and it will then automatically go to ALT mode, on takeoff, once it's above a certain groundspeed or PA or something, I can't remember what triggers it.

How do you make the 335 do that also? I've flown the airplane in question, you have to manually engage ALT before takeoff or it never will. Then ATC asked the embarrassing question "Do you have your transponder on?" I forget everytime I fly that airplane...
As noted above, that is no longer the recommended procedure. Transponder should be on ALT all the time. Reason is because some transponders (mode S-ES) are also ADSB-out devices, and the FAA requires that they be on all the time, including on the ground. As Garmin above noted, the box itself will auto-switch between ground and airborne modes.
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  #6  
Old 01-28-2020, 07:55 PM
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n82rb n82rb is offline
 
Join Date: Jan 2007
Location: fort myers fl
Posts: 850
Default

g3x so why doesnt garmin make the on and alt button both come up in alt mode. i am having a he... of a time training myshelf to turn it on with the alt button. took me three tries to get a ADSB report because i kept forgetting to turn it on with the alt button.

bob burns
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  #7  
Old 01-28-2020, 08:18 PM
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bhester bhester is offline
 
Join Date: Jan 2005
Location: Hopkinsville, KY
Posts: 903
Default Don't know

Not sure why they haven't but maybe this will help. I never turn my transponder on or off it is wired so that it comes on when I turn on the master and off when the master is turned off. Mines powers up in ALT mode always, I guess it powers up in whatever mode it was powered down in.
Give that a try!
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