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Do I have GPSS or not?


Glen Davis

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7 minutes ago, Glen Davis said:

My new to me J has a Garmin 530W and a KFC 150 Autopilot.  How do I know it it has GPSS or not.  I see no switches on the panel labeled GPSS.

Thanks,

Glen

can you upload good pictures of every corner of your panel

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That was the same setup I used to have. Took me a while to realized how the 530 and the 150 interacted. The KFC would follow the magenta GPS  purse perfectly till I came up to an approach. If the approach had a hold the KFC 150 would go off to lala  land once I passed the hold fix. I learned that it was best to switch from NAV mode to HDG mode to start the approach, then switch back to NAV or better yet APP mode once stablished inbound on the approach. Other than that the 530/150 combination flew together very well.

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In my experience, with a standard installation, you will not have GPSS unless you have something wired between the 530 and the autopilot. If you have the standard Bendix-King instruments, there are a couple options to add GPSS in between the two such as a DAC GDC31, but this usually has a switch mounted on the panel to toggle between HDG mode and GPS mode. I looked into this a while back. You other option would be digital flight instruments (Aspen, G5, etc) that have built in converters to follow the GPS track. 
 

 

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GPSS requires a device that converts GPS steering commands from the 530W to heading steering for the autopilot. Somewhere there would be a pushbutton or switch to switch the autopilot HDG input between the HSI heading bug and GPSS. When in GPSS,  you would put the autopilot in HDG mode and it would fly the magenta track including holds and DME arcs.

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This is a good reason after buying a new-to-you airplane to get with an instructor (1) who is Mooney specific, but also (2) knows the various combos of avionics and teaches you how to fly approaches with what you have.

Email them a picture of your panel and interview the person and see if they have a good working knowledge of what you have. How do I know this? I had never flown an airplane with a decent autopilot until I bought a Mooney 231 way back when that had a KFC200. I got a one hour check-out with no time spent on the avionics. It took me awhile to figure things out and I probably wasn't as safe as I should have been in the meantime. When I picked out an instructor to help me finish my instrument rating I learned a lot more about what everything would do. Shame on me,  I should have done that a lot sooner. Much more important with what's in panels now. Stepping into a glass panel without transition would make you feel like a dog feels when he's watching TV.

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5 hours ago, PT20J said:

GPSS requires a device that converts GPS steering commands from the 530W to heading steering for the autopilot. Somewhere there would be a pushbutton or switch to switch the autopilot HDG input between the HSI heading bug and GPSS. When in GPSS,  you would put the autopilot in HDG mode and it would fly the magenta track including holds and DME arcs.

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This. Legacy autopilots like the 140 don't have GPSS built-in. It is a separate unit with a GPSS switch that converts course information from the GPS into heading instructions for the autopilot. You flip the switch to "GPSS" and put the autopilot on HDG. If one was installed it would show in the avionics log (and have a an AFMS).  Some aftermarket PFDs like the Aspen have that capability included in installation.

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Sorry for being a wise arse upfront.

Here is how I know I have GPSS:

a81a69fff5fef0a421f2e1ec574e0289.jpg

If you don’t have an Aspen, Garmin G5/275 or any of Garmin’s full PFD/MFDs, you probably don’t have it. The aftermarket ones that I have seen are the DAC GDC31 and the STEC GPSS modules.
457b76d0ef1d2a8274eed372d0e4d05a.jpg

If you have an aftermarket unit, you will most likely have a switch like shown above.


Sent from my iPad using Tapatalk Pro

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If you don’t have some kind of device to be able to run your AP controller in heading mode and “cut the corner” in a 90 degree bend, you don’t have GPSS.  It appears you don’t have that capability from looking at your panel photos  

I had a similar setup as you currently have and I installed a G5 HSI which gave me GPSS capabilities.  Huge upgrade to the KFC150 and also gave me a backup AH which I did t have.  

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Good news Glen...

Based on your pics... your panel has mid nineties hardware like mine...

GPSS can be added to that...

Expect to have to research a few things... specific hardware models are better at allowing GPSS to be interfaced with...

The DAC GDC is/was a popular add on for a while...

If you got one, it would be clearly referenced in your ship’s logs...

So many color screens include the GPSS as an option...

BK autopilots are pretty good at knowing how to round the corners at waypoints... they need the GPSS to do it automatically... without the GPSS, they give a flashing light to tell you when to turn...  :)

Some BK GPS don’t have the hardware to interface the GPSS box... I think the KLN94 was extra limited... but not the KLN90B...

 

While you are looking... Turning by hand, is not so memory intensive as leveling off at an assigned altitude...

Be on the look out for things that can include altitude awareness to your tool box...

This is another box that can added to the panel... or included in a nifty color screen... :)

 

If you’re flying along.... and your GPS is following a flight plan... and your AP is in heading mode... you are using GPSS...

Otherwise...

  • your AP would be following a heading, not the flight plan...
  • The GPSS keeps altering what the AP is using for guidance, by giving it new headings...
  • Without GPSS, your AP will be in Nav mode flying to the next waypoint in the flight plan...

Great question...

Better to have asked, than to assume...

+1 For getting some assistance familiarization with your hardware...

Part of my transition training was a long X-country using all the buttons and dials... in IMC...

Just too much detail... to pick it up by reading... :)

Too much risk... if you miss something important... 

PP thoughts only, not an instrument guy...

Best regards,

-a-

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By sheer luck, someone just offered for sale a used DAC GDC31 on BeechTalk this morning.  Better get in touch quickly if you're interested.  Seller reports it was used with a GNS 530W and KFC 150.  You'll need to source the annunciator and switch separately, however.

https://www.beechtalk.com/forums/viewtopic.php?f=44&t=191283

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Great idea!

compare the benefits for the G5 to its brother the GI275...

Just to be sure...

The 275 has more stuff and costs more... but may make sense if connected to an autopilot...

You may have to become an avionics expert to have an informed decision... :)

Best regards,

-a-

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  • 2 years later...

Hello.  I'm upgrading to dual GI-275s (and I have a GNS 530, as well as a KFC-150, which is why I chose the GI-275s over G5's).    My installer seems to think that my autopilot doesn't have GPSS capabilities.   I realize now that's not accurate - but my question is: will the GPSS function be available automatically, or do I need to ensure that my installer configure the GI-275s specifically to make GPSS available?

 

Thanks!

 

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2 hours ago, hnorber said:

Hello.  I'm upgrading to dual GI-275s (and I have a GNS 530, as well as a KFC-150, which is why I chose the GI-275s over G5's).    My installer seems to think that my autopilot doesn't have GPSS capabilities.   I realize now that's not accurate - but my question is: will the GPSS function be available automatically, or do I need to ensure that my installer configure the GI-275s specifically to make GPSS available?

 

Thanks!

 

I'm not an installer, but since the KAP 150 as no inherent GPSS capability, you want to ensure that the GI175 is configured properly. 

"GPSS" generally means capable of following course/heading ("steering") commands from the GPS rather than the flight plan course. I don't know every combination out there but I've seen three distinct ways GPSS is  accomplished.

With a modern digital AP like the GFC500/600/700, GPSS is just part of the standard NAV function. Not even a separate button. If GPS is the nav source and the AP is in NAV mode, you have GPSS.

With something like the STEC 55X, the AP does it, but you have to tell it you want GPSS rather than simple NAV. You press the NAV button twice and it cycles between the modes.

Then you have units with no native capability at all. With those, GPSS is based on an interface between the GPS and the PFD (not the AP). The GPS sends the information to the PFD, which (simplistically) sees them as heading instructions. GPSS on the PFD end is "pay attention to the headings given by the GPS, not by the pilot." The autopilot is typically in HDG mode, not NAV.

I'm pretty sure your KAP 150 is in the last group. Automatic? Dunno. But unless we are dealing Garmin-Garmin-Garmin, my assumption is that it needs to be properly configured. 

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Hmmm.  Now I have to go play with mine. :)

I have a KAP-150 and Aspen 1000 Pro with GTN-650Xi.

I have been flying in NAV and GPSS.  But it seems if I have GPSS on, I should have the autopilot in HDG mode.

How about for approaches?

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Legacy autopilots have a NAV mode that tracks a course to keep you on the centerline. 

Modern GPS navigators have all kinds of capabilities beyond that: they will fly DME arcs, holding patterns, have turn anticipation for flying by a fix without overshooting, etc. These navigators interface directly with a modern autopilot to allow it to fly these curved courses. 

GPSS is a workaround to allow legacy autopilots to do the same thing. The GPSS converter (either a separate device or now more commonly built in to some piece of newer avionics) converts the GPS navigator roll steering digital commands to an analog output that the autopilot can understand. To do this, it alters the autopilot HDG input. So to fly a heading, you put the autopilot in HDG and turn off GPSS. To fly a GPS course or procedure, you put the autopilot in HDG and turn on GPSS. You only use NAV on the autopilot when tracking a VOR.

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43 minutes ago, Pinecone said:

Hmmm.  Now I have to go play with mine. :)

I have a KAP-150 and Aspen 1000 Pro with GTN-650Xi.

I have been flying in NAV and GPSS.  But it seems if I have GPSS on, I should have the autopilot in HDG mode.

How about for approaches?

Yeah, that's the way it should be working Aspen in GPSS; KAP HDG.

For approaches you want to switch to APR for the final approach segment.

I hope I explain so it makes sense. Your KAP 150 has no problem following GPS courses in NAV mode. GPS Steering helps with turn anticipation but the big deal for approaches adds the ability to follow turn commands like you might get for a procedure turn or hold in the database. If you've noticed, you saw that throughout either the HSI course needle is pointed at the inbound course. It's GPSS that flies the the entry and the turn to intercept, so you don't have to twirl the heading bug.  Once intercepting, the most common SOP I've seen is switching to APR.

Sure, GPSS will probably do a fine job on the FAS laterally, but the APR button gives you two things. A tighter lateral course and the glidepath

 

 

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