KAP140 coupled approach question

[Artiom]

Hello,

First of all quick introduction - I'm living in south SF Bay area, recently got IR. I was renting C172 for training and short trips and C182 for XC with the family. C182 wasn't IFR certified so when I got IR I had look for IFR certified plane for rent. One of the options was reasonable priced 2005 DA40, a little bit further from my home than other options. I tried it and felt in love
Hard to beat nicely equipped DA40. Transition was easy, after flying with GNS430 and GTN650 I'm quite comfortable with G1000. Low wing doesn't make too much difference, airspeed discipline helps a lot with landings.
KAP140 was completely new equipment to me. I never flew AP equipped plane before. Basic stuff like HDG and ALT was no brainer, same for NAV. However coupled approach was a different story. When I tried ILS approach I set up LOC1 to localizer frequency and identified it, I've been vectored to FAF so I turned AP off. Once I intercepted localizer I turned AP on, set mode to NAV and when I got GS indicated 2 or 3 dots above my altitude I switched from NAV to APR expecting AP to follow the glide slope. It didn't happen. AP kept flying at level altitude past GS. Question - what is the right sequence to make AP follow glide slope?

Disclaimer - I read user manual, still don't get what was wrong.

Thanks,
Artiom

[Marc_CYBW]

Here is what I do:

1. I use NAV and GPS source as matter of course in IFR flights.
2. Load ILS - Vectors Approach into Flight Plan
3. Press HDG on PFD to ensure HDG matches heading being tracked by AP/GPS combo
4. Change AP to HDG and use HDG to respond to vectors from ATC - use pre-planned approach power settings.
5. Activate Approach in FPL
6. Switch data source to ILS and verify correct localizer on PFD display
7. On final vector to intercept, switch from HDG to ROL on KAP140
8. Press APR on KAP140 to arm approach (APR is displayed in lower display line)
9. KAP 140 will capture localizer on 30 degree intercept and turn the plane.
10. KAP 140 will eventually capture glide slope - reduce power to your pre-set power settings (mine are 90 KTS /13", 2400 and TO flaps)
11. Fly on AP to just above minimums and switch off. Continue to landing or missed.

Marc

[Artiom]

Thanks Marc.
Close to what I did except step 7 - I just turner AP off when getting vectors and turned on after intercepting localizer which also put AP in ROL. So mode switching was ROL->NAV->APR. Will have to try it again next time I'm doing ILS approach.
How do you fly non precision approach with AP?

[Rick]

Artiom,

Welcome to the forum!

For what it's worth, I never used to switch to ROL mode with my KAP140. I followed Marc's steps, except I just used HDG mode for all the vectors. Once I am on the final intercept and cleared for the approach, I just hit APR and that's it.

Your problem MAY have been that the waypoint sequencing was suspended. At the bottom of the PFD, one of the center soft keys will say SUSP and be highlighted. If this is the case, you must press this button once you are vectored outside of the FAF, but before you switch to APR mode, to continue sequencing the approach. As I recall, this doesn't happen all the time, but maybe 50% - I'm not sure exactly what circumstances cause this to happen, but it is "normal" and documented (somewhere).

A non-precision approach is similar as far as lateral guidance, but you must manually set each new altitude and then set a VS rate as you past each step-down point.

[Artiom]

Rick, it is very much may be SUSP. I guess this is why Marc had Activate Approach step which I didn't have. I loaded approach expecting G1000 to activate it. Will keep an eye on it next time.

[Rick]

Rick, it is very much may be SUSP. I guess this is why Marc had Activate Approach step which I didn't have. I loaded approach expecting G1000 to activate it. Will keep an eye on it next time.

When you select the approach from the available IAPs, you can choose to either LOAD or ACTIVATE the approach. If you only LOAD it, then at some point later you must ACTIVATE it (from the menu) before the AP will fly it. The G1000 will not do this automatically for you. Activating the approach is entirely separate from the SUSP issue I was talking about, but yet another important step!

So, I guess there are at least three reasons you might not capture the LOC & GS:

1) Approach not activated (MENU -> Activate Approach)
2) AP not in APR mode (press APR button on AP)
3) SUSP is active (press the SUSP button on the PFD)

[Artiom]

Rick, it is very much may be SUSP. I guess this is why Marc had Activate Approach step which I didn't have. I loaded approach expecting G1000 to activate it. Will keep an eye on it next time.

When you select the approach from the available IAPs, you can choose to either LOAD or ACTIVATE the approach. If you only LOAD it, then at some point later you must ACTIVATE it (from the menu) before the AP will fly it. The G1000 will not do this automatically for you. Activating the approach is entirely separate from the SUSP issue I was talking about, but yet another important step!

So, I guess there are at least three reasons you might not capture the LOC & GS:

1) Approach not activated (MENU -> Activate Approach)
2) AP not in APR mode (press APR button on AP)
3) SUSP is active (press the SUSP button on the PFD)

Why would activating ILS approach in G1000 matter? It matters for LPV approach but I believe ILS is different. In case of ILS approach LOC1 provides both vertical and lateral guidance to both the pilot and (I assume) AP. So I set localizer frequency and identified it and switched to LOC1 using CDI soft button on G1000. Both lateral and GS were 2-3 dots off when I switched to APR mode. Isn't it enough for AP to follow the glide slope? As I understand APR mode is more precise version of NAV plus vertical guidance.

[Rick]

Why would activating ILS approach in G1000 matter? It matters for LPV approach but I believe ILS is different. In case of ILS approach LOC1 provides both vertical and lateral guidance to both the pilot and (I assume) AP. So I set localizer frequency and identified it and switched to LOC1 using CDI soft button on G1000. Both lateral and GS were 2-3 dots off when I switched to APR mode. Isn't it enough for AP to follow the glide slope? As I understand APR mode is more precise version of NAV plus vertical guidance.

Thinking about it now, I agree with you - activating the approach (or even loading one, for that matter) should not be required for the AP to fly a coupled approach. I just never use it that way, but no reason it shouldn't work. I still believe that the AP will not intercept the GP/GS when in SUSP mode, though, so that may have been your problem.

[Marc_CYBW]

The reason to activate the approach is to have the missed procedure ready to go. On the missed switch to GPS and NAV.

[carym]

The KAP140 is funny in how it will capture/couple and ILS. You must be close to, but not on, the LOC and must have an intercept angle that is about 30 degrees. If intercept angle is too shallow you will be too close to the LOC and it will not capture. On many occasions I have had ATC turn me too close to the LOC and I would not caputre an "activated" approach. While this is not supposed to happen with the KAP140, it does. Be prepared to hand fly the approach and turn off the KAP140 if that LOC isn't captured when you expect it to be so. If the LOC is not captured, the glide slope will not capture either.