In the C172 it used to be that when I hit the APR button the autopilot would display APR AP GS. For some reason now GS flashes for a second but then turns off leaving only APR AP lit up. When I look at VOR however I still see that I'm lined up with the glideslope. Can anyone explain this? Thank you.

Tell me, is the GS operative? you'll see the letters GS in a little window on the right side of the guage, if not, there will be a red and white striped flag in the window meaning it's inoperative. The other question is, are you tracking a VOR or a ILS? VOR will not have a glideslope.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

>Tell me, is the GS operative? you'll see the letters GS in a>little window on the right side of the guage, if not, there>will be a red and white striped flag in the window meaning>it's inoperative. The other question is, are you tracking a>VOR or a ILS? VOR will not have a glideslope.I am definitely tracking an ILS because I've done this approach several times before during the past few days but now it's acting weird. The actual ILS is LOC/DME 31 (IPZV) 108.50 at LaGuardia airport. The VOR guage does say GS and it does show the little flag but the autopilot in the radio stack only shows APR whereas before it would show APR GS. Thank you.

"The actual ILS is LOC/DME 31"You are getting the terminology mixed up. The "instrument approach" for Rwy31 is LOC/DME. It is a localizer approach only, no glideslope. DME is also provided. You will see a multi-bar VASI on the left side of Rwy31 for vertical guidance.By definition, an ILS will provide electronic horizontal AND vertical guidance (localizer and glideslope).I flew the Instrument Approach for Rwy31 and I too did have GS before passing the airport but lost it upon passing the airport.This is because the localizer for Rwy 13 also uses 108.5 and has GS. When you fly over the GS antennas, your GS indicator will flip off, just like passing a VOR.From the description on AIRNAV for RWY31 LOC/DME, it appears they could not use GS effectively for RWY31 due to obstructions. (Go METS!)http://www.airnav.com/airport/KLGAHTH,Jim

Jim, thank you very much for the very helpful explanation. You were right, I guess I just never noticed the GS actually going off.

Given this, and your other posts, I'm guessing you're fairly new to flight sim, right?If so, then I recommend you follow the `tutorial path` actually in the sim, sticking with the default aircraft for the time being. This is actually one of Microsofts hidden gems that more experienced simmers and real world flyers never go on about because we know it all anyway. :-)But the King lessons and the Machado tutorials are an integrated part of the experience, designed to take the ab initio computer flyer through most of the aspects of the sim, and many of the aspects of real world flying, getting more complicated and systems oriented along the way.Make full use of those Help files and the King videos - they are very informative and helpful. It's just that their `Ma and Pa` apple pie acting skills makes you want to puke.:(. Call it airsickness and then it's even more real!Allcott