KAP 140 autopilot FAQ

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JetJockey
Airman First Class
Posts: 73
Joined: 06 Nov 2011

Re: KAP 140 autopilot FAQ

Post JetJockey »

Bert Pieke wrote:If I am flying with the RXP GNS in GPS mode and the autopilot in NAV mode,
and push APR, the autopilot goes to HDG mode - only a second push of APR
gets me to approach mode.

Secondly, with an LPV approach, the autopilot does not capture the glideslope,
but holds altitude, when in APR mode.

Edit: I am aware that the basic KAP140 does not capture LPV glideslope (only ILS),
but later KAP140 models do... so please can you upgrade your installed KAP140 to WAAS
capability? This would make sense with a WAAS equipped GNS530 in the panel.. :-)

Quoting from a RW KAP140 guide:

"NAV/APCH Modes

... In NAV mode, the autopilot will track whatever the CDI is set to, whether it be GPS, VOR, LOC, or ADF (if the airplane is equipped). In approach mode, the sensitivity of the autopilot is increased, so it holds to tighter tolerances. It also will track the glide slope on an ILS approach in APCH mode (as well as the glide slope on a WAAS approach, if equipped)."
+1 This would be an excellent u/g for a modern trainer.

Ray
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jimjones
Airman
Posts: 32
Joined: 10 Dec 2009

Re: KAP 140 autopilot FAQ

Post jimjones »

Autopilot malfunction and solutions.

Update v1.22

While trying to monitor clickspot problems and use the autopilot my computer experinced some anomalies during a 106 min test. After triming and staying trimed for a minute a succesful change to a set altitude was accomlished and stayed at altititude for 20 minutes. After hovering the cursor over a clickspot to see captions to test if they had disappeared it was noticed that the plane was beginning to OSCILLATE and the oscillation INCREASED in aplitude with time. This seems counter to what I would expect. After reaching a large ocillation of about 1500 to 2000 FPM the oscillation then began to
decrease in amplitude and then settled down to near 0 FPM. I was having similar problems just going into and out of the FSX menus.

1) Why did hovering over a captioned clickspot cause oscillations?
2) And why the increase in oscillation amplitude?

This, problem 1, was not occuring in full screen mode, so perhaps the higher frame rate has something to do with the problem. Fullscreen FPS=19, windowed mode FPS=11. The problem is akin to that of trying to fly at a slow FPS and not bring able to control the plane.

Problem 2 may be a programming problem but who knows?

In conclusion for best results with the autopilot use full screen mode, maximize framerate and avoid clickspot hovering.

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bmd
Airman
Posts: 29
Joined: 24 Aug 2009

Re: KAP 140 autopilot FAQ

Post bmd »

Hello,

I have bought the A2A C172R Trainer from SimMarket Sept, 29 2013. i.e after the update 1.03 became available. And I have had probleem using the autopilot. It seem to me taht because the purchase was after the rerlease of the update 10.3, the installation of this update was not necessary.

However I have installed today the update 1.03. And now I can use the autopilot without problem. So whatever the date of purchaase, the installation of update 1.03 may solve your problem with the autopilot.

Have a good day

Benoit

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Lewis - A2A
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Re: KAP 140 autopilot FAQ

Post Lewis - A2A »

bmd wrote:Hello,

I have bought the A2A C172R Trainer from SimMarket Sept, 29 2013. i.e after the update 1.03 became available. And I have had probleem using the autopilot. It seem to me taht because the purchase was after the rerlease of the update 10.3, the installation of this update was not necessary.

However I have installed today the update 1.03. And now I can use the autopilot without problem. So whatever the date of purchaase, the installation of update 1.03 may solve your problem with the autopilot.

Have a good day

Benoit
Yes the test update is required as its not part of any installer. It's currently a test update that will eventually make it into the next Accu-sim core update


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bmd
Airman
Posts: 29
Joined: 24 Aug 2009

Re: KAP 140 autopilot FAQ

Post bmd »

Hello Lewis,

Thank for the information. Have a good day

Benoit

Heronjr
Airman
Posts: 42
Joined: 10 Sep 2013

Re: KAP 140 autopilot FAQ

Post Heronjr »

Last flight from KCOE-KYKM Coeur d'Alene-ID to Yakima-WA, I had problems approaching the ILS at KYKM, as the GS, though captured, was not sensed by the AP. The speed was 65-70 by the time of LOC interception, the AP accepted the APR change from NAV, and the GS letters appeared on the AP. The HDG was set in the same radial of the LOC. I have just upgraded to 1.03, and with the previous version I could make some ILS approaches successfully.

Thanks for ideas

Heron
Heron Domingues, Jr

Heronjr
Airman
Posts: 42
Joined: 10 Sep 2013

Re: KAP 140 autopilot FAQ

Post Heronjr »

Tested again the same ILS27 approach at Yakima KYKM and all worked well. I really don't know what could went wrong yesterday. Is there a difference between going direct from HDG to APR and going from NAV to APR?

Regards

Heron
Heron Domingues, Jr

Bert Pieke
Senior Airman
Posts: 104
Joined: 16 Sep 2013

Re: KAP 140 autopilot FAQ

Post Bert Pieke »

I have found that there is indeed a difference... not sure from the documentation
whether it works as the real thing or not.

Going via HDG, rather than straight from NAV, gives me better and more consistent results.
Bert

awash2002
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Location: KCZL

Re: KAP 140 autopilot FAQ

Post awash2002 »

The altitude hold just goes crazy up and down +/- 1500fpm will not hold altitude severe porpoising up and down 1500 fpm up and down I will hold off on flying the 172 until this problem is fixed
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lonewulf47
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Re: KAP 140 autopilot FAQ

Post lonewulf47 »

Heronjr wrote:Tested again the same ILS27 approach at Yakima KYKM and all worked well. I really don't know what could went wrong yesterday. Is there a difference between going direct from HDG to APR and going from NAV to APR?
In what situation would you go directly from NAV to APPR? However just be sure you manage the HDG bug correctly i.e. always set it to the INBOUND COURSE of the relevant navaid used - no matter whether it be a VOR or an ILS. If you are closing in to an ILS course in coupled NAV it is in any case adviseable to change to ROL mode shortly before intercepting the LOC, set the HDG bug to the LOC inbound course and THEN arm APPR. This way no unwanted HDG change to a possible attempt to a 45° intercept occurs. The KAP140 IS tricky but nevertheless easily manageable once you understand its limitations.
Oskar

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lonewulf47
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Re: KAP 140 autopilot FAQ

Post lonewulf47 »

awash2002 wrote:The altitude hold just goes crazy up and down +/- 1500fpm will not hold altitude severe porpoising up and down 1500 fpm up and down I will hold off on flying the 172 until this problem is fixed
Not sure where the problem is. Can you give more information about the issue? Just "porpoising up and down" is nothing to base an investigation upon. It might be a good idea to provide information about weight distribution, airspeed, altitude and ROC/ROD prior to engaging ALT HOLD as well as the present update state. Here I do not see any such porpoising.
Oskar

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Bert Pieke
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Re: KAP 140 autopilot FAQ

Post Bert Pieke »

lonewulf47 wrote:In what situation would you go directly from NAV to APPR?
When flying an RNAV (GPS) approach, it would make sense to switch from NAV to APPR after
the turn to final..

However, I've also found that using ROL and HDG modes prior to APPR, works a lot more
reliably.
Bert

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Lewis - A2A
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Re: KAP 140 autopilot FAQ

Post Lewis - A2A »

awash2002 wrote:The altitude hold just goes crazy up and down +/- 1500fpm will not hold altitude severe porpoising up and down 1500 fpm up and down I will hold off on flying the 172 until this problem is fixed
Check your FSX frames, if they are low you are experiencing FSX deterioration and no fix we give will fix the issue as its an FSX issue. FSX has a feature/issue/bug that is well known but has been forgotten by many. As the frames lower and FSX struggles to perform the program will start to turn stuff off and degrade performance of things like flight models and such. This in turn will have an affect on our realistic simulated autopilot and will cause issues such as some users have experienced. This also explains why we have not been able to reproduce the issue on our machines and why most users run OK. The issue was found and a reproducible case made by one of our testers and community member Oracle by setting his settings to max. The resulting low FPS causes all manner of issues and was cured when he set his PC back to his normal playable settings.
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awash2002
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Re: KAP 140 autopilot FAQ

Post awash2002 »

OK thanks Lewis I'll do that
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SkipperMac
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Re: KAP 140 autopilot FAQ

Post SkipperMac »

Bert Pieke wrote: However, I've also found that using ROL and HDG modes prior to APPR, works a lot more
reliably.
... as recommended by the manual and lonewulf above. That's what I love about this autopilot - you have to think rather than just select 'magic modes'
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