Let me start by saying I have watched a variety of YouTube videos about ILS approaches to try to learn all about doing them. I can do most of the setup work can arrive correctly to find the glideslope.

However, the part I cannot get a handle on is how to get the plane to automatically descend properly. No matter what I do I always seem to end up just flying over the airport instead of coming in for a landing.

Here the most recent approach plate I have been trying to work with (flight id from KTVL to KRNO):

https://imgur.com/a/3VjDaWz

I am flying the Bonanza G36 with G1000. I have entered the approach data in the PFD. I have the flight plan loaded. I have the ILS frequency set and the approach heading set too.

It looks like the chart says I should be at 11,000 feet at the top of the approach but I can't seem to figure out how to descend properly and automatically.

I am missing something that causes the plane to descend automatically. When I get close I hit the Approach button on the autopilot.

I hope I am explaining this well enough to get some help. Watching more and more videos doesn't seem to be getting me there.

Can anyone help me? Thanks.

Edited January 2Jan 2 by Rob G
More Info

First things to check are
1) have you followed the initial descent plan down to the EPOSE at 8200ft where you start intercepting the Glideslope (this can be done manually or using VNAV mode on the G1000) ? (EPOSE is the first point where you would expect to intercept the Glideslope and you could descend manually down to CALEG or DUYEP and intercept it lower if you wanted)

2) have you switched the CDI to LOC1 or LOC2 (depending which NAV radio you've set the ILS frequency on) ? If the CDI mode is set correctly you should see the the green CDI needle showing your horizontal track relative to the ILS and a Glideslope marker to the right of the altitude bar

If everything is OK then approaching EPOSE the PFD should look something like this

 

Here the ILS frequency is set on NAV1 and I can see then correct identity code on the frequency IAGY.
The CDI is set to LOC1 so is using that frequency and I can see the Glideslope indication to the right. The Green diamond is above the centre line so I'm below the glideslope (which is correct) and as the diamond comes down and reaches the centre as I reach EPOSE and since I'm in AP approach mode the plane with start to descent automatically to track the glideslope.

Edited January 2Jan 2 by Matchstick

edit : Matchstick added a pic to his original reply while i was posting this message so this one not really needed 😄

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To complement what Matchstick correctly said, here's a little picture of what you should see. Sometimes a little pic helps so you can compare with what you got.

 

if you don't see the GS indicator at the top then it will not descend. Make sure you are at a good altitude to catch the glidescope by checking the chart and in LOC1 mode by pressing in the CDI button until LOC1 appears.

🍺

Edited January 2Jan 2 by Bad_T

You beat me to the screenshot AND did it better 🙂

Hi Rob. Further to what Matchstick and Bad_T say above, here's a video of an approach into London City Airport (EGLC) with the G1000 suite in the Kodiak. It's an unusual approach as the ILS for runway 09 is angled at 5.5° instead of the normal 3° but the principle is the same.

At the start of the video you can see I'm following the flight plan loaded into the G1000. I'm at 7000ft. agl but above that you can see I have entered an altitude of 2500ft. into the autopilot. This is the height I want to intercept the glide slope at the final fix on the ILS.

As I approach the STAR I press VNAV on the autopilot. At the top of the PFD you can then see 'VPTH' appear in white. This means VNAV is armed. At 5 minutes in you can see on the moving map a white circle ahead of the plane with TOD next to it. This is top of decent. When the plane reaches this point the VPTH on the PFD flashes green and then stays green. VNAV is now activated and the plane starts to descend to reach 2500' at the final fix where it will intercept the ILS glide slope signal.

The G1000 that Working Title have given us is a pretty fantastic unit and very capable. 

At 8.45 you can see the G1000 switch from GPS mode to LOC mode as we approach the final fix and I press the APR button on the autopilot, GS appears in white to show the glide slope is armed and shortly after flashes green and then stays green to show the glide slope is active and the autopilot decends as we follow the glide slope down. 

The G1000 does not have an auto land facility so at 750' I disengage the autopilot and we land manually.

Good luck!

Edited January 2Jan 2 by DD_Arthur

Others have given good advice relative to the WT G1000, but I'd add one more thing.  What isn't completely obvious in the FAA approach plate's profile view is that the descents after localizer intercept but prior to EPOSE are really step-downs to be managed by you - whether manually or through VNAV - and guidance is not provided by the ILS system's glideslope signal. 

Glideslope intercept is intended to occur at EPOSE at 8200' at which point you now have both vertical and horizontal guidance from the ILS.  Prior to this you only have horizontal guidance provided via the localizer.

While this point is highlighted by the X in the profile, the continuous descent shown might lead someone just starting out to believe that the ILS "has your back" in the descent prior to this.

This is one of the things I prefer in Jeppesen approach plates, as the profile view visually represents the step-downs as such, rather than as a continuous slope, making the step-downs and the glideslope intercept point more obvious.

 

Scott

Edit:  Here's a visual example from a "Flying" magazine article:  https://www.flyingmag.com/chart-wise-two-kinds-of-approach-plates/

Second edit: When I said there is no vertical guidance, that's not strictly true.  You should see a glideslope signal before intercept, of course, but you're not intended to intercept it until the indicated point.

Edited January 2Jan 2 by tttocs

Yes you absolutely might not get a valid glide slope or localizer signal outside of 18 miles...sometimes the sim is quirky too.

If you're not receiving a glide slope signal on green needles/VLOC...

You could set 8200 in the altitude selection and use VNAV to descend (while the approach is loaded but you're still in GPS/magenta needles).  But you have to make sure the plane is not descending beyond the published altitude constraints.  You should definitely have the glide slope by EPOSE if not something is wrong hehe.

If I'm on magenta needles my technique is to sync HDG to my current, change to heading mode (if on AP) and maybe use VS to descend and then swap to VLOC/green needles to.see if there is a valid glide slope signal.  If so I just press APR and it should continue descent.

Just in case you're wondering, (and depending on the MIA/MVA), in real life you'll hear something like "Bonanza 12345, cleared direct APIME, cross APIME at or above one one thousand, cleared straight in ILS runway 35L, Reno airport."