View Full Version : Precision Approach Procedures - 3400

08-13-2017, 10:18 PM
I'm having trouble figuring out why the AP sometimes does not intercept the GS as I'm expecting it to do.
This has occurred on ILS and LPV approaches.
Is there a requirement for VER ARM to be selected at some point in the approach before GS intercept?
Am I arming it too late? Or is there some other issue at work?
Is there a manual that I've missed that speaks to approach procedures.
I'm a retired airline pilot, but relatively new to the AF 3400 and the RV-10 I am flying.
Please excuse my ignorance and point me in the right direction to tighten up my instrument procedures.
Any help would be much appreciated.

08-14-2017, 01:46 AM
what ap do you have?what gps are you using?
n668g rv10

08-14-2017, 04:49 AM
As Alan requested, what GPS are you using? Is it a certified one that has approach data available? Is it hooked up via ARINC or just RS-232? The approach data only gets transferred to the EFIS/AP via ARINC. Is your AP in GPSS mode?

Yes, you want to be in VER ARM mode before you start your approach. The mode will automatically change when the glideslope is obtained. You'll see the vertical guidance on the screen when it sees the glideslope. Rob does have several Youtube videos online that may help you.

I've found that if you adjust your altitude manually on the EFIS to those that have the altitude underlined on the chart (i.e. IAF, FAF), I'll get more consistent glideslope intercepts.

08-15-2017, 06:02 PM
After some investigation, the autopilot is a Trutrak "Digiflight II VSVG" and it is in GPSS mode. The GPS is hooked up with an ARINC converter, so it gets all the necessary data.
So, I think the hardware is suitable, and I think I just need to be more precise in getting to the proper altitudes on each approach segment (unless getting steered in with ATC vectors).
Thanks Bob and Alan for responding. Much appreciated.
Jim Schwartz
RV-10 N921AC