Hi,

I have no problem staying on the localizer with the default Garmin, but I have much difficulty staying on the glideslope.  I have been using the throttle to make adjustments, but it still is a problem. The autopilot is on, the APR mode is selected, NAV switch is in NAV as I approach the ILS feather, and the ALT button is on. I am at the correct altitude to approach the ILS. Should the ALT button be turned off at this point for the descent or left on?  Thanks.  Tom

It would help to know which aircraft you're talking about and the type of approach.  Every autopilot is different (seems that way) but, in all the aircraft I fly, all you have to do is click APR. It will 'arm' until intercept and then just take over.  It's good that you're in NAV before you click APR, if only for an instant.  Some aircraft (particularly Garmin equipped aircraft) won't handle it right if you don't and it ensures that the localizer is captured. 

As Gregg said above:

 

Many autopilots will not capture the GS of the LOC is not already centered (at GS intercept) and your AP is not set to NAV first.  It doesn't take too much imagination to think about what might happen if you started descent on the GS and you were not centered on the LOC-  there could be obstructions (such as towers, cranes, etc.) that might give you a bad day if you were off the LOC "centerline" and you descended below FAF altitude.

 

It's hard to know from your message what is going on regarding the LOC- is it centered, and do you have the NAV button on?

 

You could have more fun and manually fly the ILS, of course    That's the best part of the flight-  why let "George" have all the fun?

 

Thanks, Bruce.

 

Make sure the NAV-GPS switch is in the NAV position. Approach below the GS. The autopilot NAV button does not have to be pressed on any aircraft that I know of (default for sure). The ALT should be on and it will go off when captured.

 

Dave

It could also be possible that you are too fast, I've seen it quite a few times that the AP (the default one, that is) doesn't capture the G/S at higher speeds - say 250kts, which would probably be way too much in real life, too.

Thanks for the help, guys. I am flying the Carenado 182RG with the Garmin 500 installed in my panel. I fly the extended Pink line from the ILS feather until right before I get to the beginning of the green feather. I usually have the A/P APR pressed on. I then switch from GPS to Nav with the toggle switch as I arrive at the beginning of the ILS feather. Thanks again.  Tom

I have a Carenado C182Q but it has the RXP 530 in it.  Not sure if that matters.  

 

Sounds similar to a problem I had a while back.  Click NAV on the A/P, then switch the GPS from GPS to VLOC (either with a switch or with the CDI button...however it works in your airplane) so that you're navigating laterally on the localizer.  Then, if you have a G/S signal, click the APR button.  Airspeed should be around 90 KIAS with a notch of flaps and gear down.  It should hold altitude until the aircraft is on the G/S and then automatically begin descent.

Thanks for the info, Gregg.   Tom