[newtech]

I have a dual screen g3x classic panel with tt gx pilot, gtn 650 and no GMC 305. After entering and activating an approach when can/should you enter ap appr mode? My system seems to be working but after loading and activating an approach I don't get the "ap appr" soft key when pressing the alt/pitch soft key.

GDU 370. V 10.20
GTN 650 V 5.13

 

[Auburntsts]

I was taught to select approach mode on the autopilot after being cleared for the approach. As for why the ap appr soft key isn't appearing, I have the same setup as you so it sounds like to me something between the 650 and the G3X isn't configured properly. The only other thing I can think of, IIRC is the G3X the ap appr soft key is only available for approached with vertical guidance so make sure the loaded approach is an ILS or appropriate GPS (LPV, LNAV/VNAV, etc).

 

[Bill.Peyton]

I have a 3 screen legacy system. First, the AP APPR must be armed while you are still under the projected Glide Slope/Path. Once you get "on top" of the glide slope/path the A/P will not provide you vertical guidance.

I generally arm the AP APPR prior to getting established on any leg of the approach. For Vectors to Final I arm the AP APPR when I am within a few miles of the final approach course.

If you are on a GPS approach that requires a step down prior to the FAF and if you have armed the AP APPR, you can select the new lower altitude, then select VS and input the VS using the joy stick. You must get down to the selected altitude before the GS/GP will arm.

I usually don't bother selecting the step down altitude, I just let the G3X capture the GS/GP from underneath prior to the FAF. It eliminates that additional step and will always keep you above the step down altitude.

I just realized that you stated that you did not see the APP APPR softkey active. I also have the TT A/P. I see the APPR key active anytime I have loaded and activated an approach. It sounds like you might not have set up either the GTN or the G3X to receive the data properly. I would be worth checking your settings.