Autopilot / ILS

[Colin Payette]

I'm trying to make the ILS 25L Approach into KLAS with an autopilot, and after a few failed offline practice attempts it's driving me mad.

- I am flying 170 knots, heading 255 from POKRR to PRINO at 8000'.
- I have 111.75 tuned in to NAV1 and a course of 255 tuned in.
- I change from GPS to NAV1

What I expect to happen is for the plane to intercept the localizer, disable the altitude hold and start descending towards the runway. What does happen is the plane just cruises merrily along at 8000' right over the top of the airport. This is in a Lear 45 if that makes any difference. What am I missing?

[Keith Smith]

Look for a VNAV or APP mode on the a/p. Right now, I'm guessing there's no reason the a/p should be releasing the ALT hold. It's likely that it has no idea that you'd like it to track the glideslope. Also, ensure that you're intercepting the glideslope from below. That, and you should ignore the GS until reaching the GS intercept altitude. Before that, just treat it as non-precision and follow the stepdowns until reaching the GS intercept.

[Colin Payette]

That must be it. I'm using the Saitek multipanel and am just leaving the NAV button on. There's another one that says APR. I did manage to step down and get the little glidepath diamond to show up, but couldn't figure out why it didn't intercept the glidepath. Setting it to approach mode sounds like the key. Thanks!

[Mark Hargrove]

Two things:

-- The FSX autopilot has to intercept the glideslope from BELOW or it will usually not capture and track it.

-- The autopilot must be in APR (approach) mode or it will not track the glideslope. If you're using the Saitek panel, track the localizer inbound in NAV mode until the glideslope indicator (or needle if you're flying steam gauges) starts to move downwards towards center. At about 1 dot deflection, press the APR button on the saitek panel. The NAV and ALT lights should go out, the the APR button should illuminate. After a few seconds of "hunting", the autopilot should capture both GS and localizer and fly the approach for you. You, of course, are responsible for power settings on anything that doesn't have auto-throttle.

-M.

[Colin Payette]

It worked! Thanks Keith and Mark. I think I'm ready to fly the LAX-LAS online.

I'm doing it with a glass panel (iPad w/ AirTrack) for now but am going to want to mix in some practice on gauges too.

[Mark Hargrove]

Excellent!

Just to check -- you are using SPAD rather than the Saitek drivers, right?

-M.

[Colin Payette]

I've been using the defaults but some things bug me about it. I've never heard of SPAD before your post, but I just looked it up and am going to give it a try! Being able to set my altimeter with it would be awesome.