Does Autopilot Approach Mode Control Altitude?

[BTilson]

I was exploring Northern Germany earlier today in the Baron 58 and I spotted a nice ILS equipped airport on this little island about 80 NM away, so I figured I'd head out there and see how well the AP ILS Approach mode worked. Finally made it out to the airport and about 20 NM out I enabled the approach mode (I had already tuned in the ILS into Nav1 and set the heading appropriately) and absolutely nothing happened. I at first assumed I was doing something wrong, but after a minute it kicked in and the plane started banking around to intercept the beacon. It lined itself up pretty well with the runway, but it seemed to pay no attention to the glideslope. It pretty much just flew a level flight right over the runway. The first thing I thought to check was to make sure that the ILS did indeed have a glideslope and that it wasn't just a localizer. Just to make doubly sure, I turned on the visual flight path, and sure enough, there was a long line of red rectangles going down to the end of the runway, just as I expected. I tried this a couple more times, and every time the plane seemed to ignore the glideslope. It would pick up the localizer beacon and line itself up quite nicely, but it never seemed to want to follow the glideslope down.

Anyone have any ideas or input on this? I am assuming I am just missing some key bit of knowledge on how this works, since this was my first time trying an ILS approach with the autopilot active.

Thanks!



Just in case anyone else wants to check it out:

EKRN Airport (Ronne)
ILS: IAR 109.35 Hdg 112

[Sir_Crashalot]

Was the altitude hold on your autopilot active at the moment you intercepted the ILS?

Crash

[BTilson]

I think it was the first time, but after that first attempt, it wasn't. I flew the go around manually and lined myself back up and then hit the approach button on the AP.

[Brett_Henderson]

Some approaches that appear like ILS are what's know as "Localizer only approaches".. There is no glide slope.

Sounds like that was one of them..

[TSC.]

Did you intercept the glideslope from underneath?

TSC.

[BTilson]

So the short answer to my question is that when approach mode is engaged on an ILS approach with glideslope, the plane SHOULD indeed follow the glideslope down? So either a) I am just doing something wrong, or b) that airport is just a localizer approach and I need to study up some more on my instrument approaches

Thanks!

[dave3cu]

Just checked it out (EKRN-ILS Rwy 11) and it does have glideslope and functions properly.

For the APR mode to grab the glide slope you should be in level flight and BELOW the glideslope on your final vector to intercept the ILS.

[quote]Intercepting the glide slope  (from the FS2004 Learning Center)

In order for the autopilot to capture a glide slope, you must intercept it from below. Although some real-world autopilots can capture a glide slope from above, standard operating procedure is to intercept and capture glide slopes from below. Thus, many real-world autopilots

[BTilson]

Aha! I'd have to say that that was most likely my problem, trying to intercept it from above instead of below. I'll have to give it another try sometime soon and see if that solves my problem.

Thank you all so much for the help! Seems like there's always more to learn in this hobby.