WAAS - Roll Steering & KFC 200

[CoachTom]

Which GPSS to install with the KFC 200 and 530?

I am in the decision process of either upgrading the 530 to WAAS and adding GPSS or leaving it non-WAAS as the predominance of my approaches are using the ILS anyway.

The KFC 200 is the FD/AP installed and I did not know which GPSS would be best suited for it as it is an analog unit. If all of the GPSS' perform the same and have the same relevance in operation, then it would a decision between price and bells and whistles.

Regard the "extras"; the Icarus Sam has many additional features but costs +3 AMU to buy and install.  Conversely, the DAC GDC 31 is binary as it is egaged or disengaged and costs +2 AMU.  I do not have a reference point in price for the S-Tec or if it is like the Icarus or the GDC...

Any wisdom or lessons learned along this decision path would be greatly appreciated!!

[Guest Anonymous]

The Garmin GNS units output roll steering on the ARINC 429 interfaces.  The best option for any Bendix King autopiot is to use the ARINC 429 output of the GNS unit into an Allied Signal KA-90 Interface Adapter.

RFB

[jlunseth]

I have the 430 AW, the KFC 200 and an Icarus Sam.   I have had the Sam since the beginning of the summer.  I really like it.  I don't have any experience with any of the others.  An example of what the combination will do is an ILS.  You load the ILS in the GPS and choose your IAF, then put the KFC in "Heading" mode and push the button to activate the SAM.  Turn the course arrow on the HSI to the inbound course for the ILS, which you will need once you are on final.  The SAM and GPS will now fly the approach to final for you.  When you are established on final you choose Appch on the KFC.  The KFC will then couple to the Glideslope and take you right down to DH.

The combination will fly RNAV approaches seamlessly.  All you need to do is load and activate the approach (when cleared direct to the IAF by ATC).  It will anticipate all the turns and take over the job of keeping you on the approach course.  At the FAF I turn Alt Hold off ( I don't have Alt Select, just Alt Hold), then use the CWS to set a nose down pitch appropriate to the descent rate I want.  From there the plane flies itself down to the MDA. 

They couldn't make it much easier.

The SAM does alerts, which is one reason I got it.  You initialize it at the start of the flight by setting Altimeter, the altitude of your destination airport, and your cruise target.  It will alert you as you get to cruise altitude, and will also alert you if you are falling off cruise altitude, which is handy if something happens with the AP when you are not watching it.  It alerts you on approach and landing to "Check GUMPS" and also gives a gear alert if you get too low and don't have the gear down.  The button will read out your next waypoint and time to the waypoint, so if you are not in radar you can read the reporting information right off the button instead of having to calculate it or follow a chart. 

[danb35]

Quote: jlunseth

At the FAF I turn Alt Hold off ( I don't have Alt Select, just Alt Hold), then use the CWS to set a nose down pitch appropriate to the descent rate I want.  From there the plane flies itself down to the MDA.

[jlunseth]

Well, I wrote a nice long reply, didn't copy it, and it did not transmit.

The short of it is no, an ordinary vanilla RNAV (GPS) approach does not have a glideslope.  There are RNAV's that do, but many do not and on an ordinary RNAV, if there is a glideslope, it will not be published.  You are thinking of a WAAS or LPV approach.  The way to tell these on a plate is that there is a "WAAS" in the frequency box. 

[danb35]

On my 430W, a glideslope is generated on many non-LPV approaches--in fact, I'd say most of them.  There are some criteria where the GPS won't generate one, but it seems that it does by default.

[Jeff_S]

I have a Garmin 480 tied to an S-TEC55 A/P with the GPSS system. Flying pretty much any approach can be a nearly hands-off affair. When flying an RNAV approach with GPSS all you need to do is maintain your speed...and remember to hit the APR button on the S-TEC unit outside the FAF. If you don't do that, it won't capture the glideslope and you'll wonder why you aren't descending! (Learned that one by experience of course.)

When flying an ILS, the only difference is that once you are on or approach the final approach path, you need to be sure to hit the NAV button on the STEC so it will track the ILS signal instead of trying to follow GPS. (This is because the G480 will have automatically switched the CDI output to NAV, its software being much smarter than the wetware between the pilot's ears.) Otherwise you'll find yourself continuing on past the approach path and wondering why your plane isn't turning. (Learned that one from experience too!)

[jlunseth]

Yes, made the same mistakes.  On mine (KFC 200) it appears to be important to switch to Appr. before the glideslope hits the center line on the HSI.  If you have overshot the glideslope, even a little (you are above it), the AP does not seem to want to couple.  So best to switch to Appr. before you get there. 

It is really cool to have the plane take you right down the glideslope.  Gives you time to manage speed and set up for landing in a relaxed way.

[FlyDave]

Quote: jlunseth

Yes, made the same mistakes.  On mine (KFC 200) it appears to be important to switch to Appr. before the glideslope hits the center line on the HSI.  If you have overshot the glideslope, even a little (you are above it), the AP does not seem to want to couple.  So best to switch to Appr. before you get there. 

It is really cool to have the plane take you right down the glideslope.  Gives you time to manage speed and set up for landing in a relaxed way.