Ranking and Comp of AutoPilots

Discussion in 'Flight Following' started by TimRF79, Feb 22, 2021.

  1. TimRF79

    TimRF79 Pre-takeoff checklist

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    As I am looking at my next plane, I realize I don't know much about autopilots.
    Which autopilot is better than who, which has what functions/limitations.
    Has anyone ever compared them and made a chart.
    Especially:
    KAP140, GFC 700, GFC 500, STEC 55x, TRIO, TruTrak, original Cessna AP's
     
  2. asicer

    asicer Final Approach

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    Autopilots are largely computers of some sort. Just like laptops, latest generations are generally better than previous generations.
     
  3. TimRF79

    TimRF79 Pre-takeoff checklist

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    Depends, for the normal work functions (Outlook, Excel) the difference of a I7 4th gen to an I7 11th gen is not noticeable...
     
  4. asicer

    asicer Final Approach

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    The GFC700 is integrated to the G1000, so it's not something you can easily add. The GFC500 is integrated with the G5 and GI275. It has the same capabilities as the GFC500 but it has a dial that you can spin for AS/VS climbs instead of repeatedly tapping the buttons like on the GFC700.

    The Trio and TruTrak are of the same generation as the GFC500 but have less capability. Both don't have flight director outputs, aren't approach certified and can't follow a VOR/LOC/ILS (GPS only). The plus side is that neither require a G5/GI275 and are cheaper/easier to install.

    I don't know much about the STEC 55x, so I'll let someone else weigh in.

    The older units don't have GPSS built-in. They all need an external converter of some sort. There's a couple flavors of KAP140. Some can do an altitude hold, some can do altitude pre-select and some can do neither. All of the KAP140's are rate-based and therefore depend on a turn coordinator (on G1000 planes its hidden behind the panel).
     
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  5. NordicDave

    NordicDave Pattern Altitude PoA Supporter

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    :yeahthat:

    The hot ticket is the the GFC700 in the 2nd and newer generation G1000's, or the GFC500 which is the same AP developed for retrofit. All digital from head unit to servo's. Stunning performance following compass vectors when needed by ATC or GPS/VOR/ILS/LOC. Combine with a Gramin GPS the GFC500 will also provide VNAV in addition to RNAV navigation.

    It's what everyone wants, but might outside of budget.

    All else is pretty much a compromise, though given this is POA follow-on posts will have guns blazing for something else.

    I have an old Cessna wing leveler 1 axis A/P and still going strong which tracks headings and GPS. It reduces my workload when needed and will upgrade later as funds permit.
     
    Last edited: Feb 22, 2021
  6. NordicDave

    NordicDave Pattern Altitude PoA Supporter

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    You can make your won comparison chart based on what is required for your missions. Consider Analog (primarily rate based) verses partial or full Digital?, Tracks a heading?, RNAV only or RNAV + VNAV?, 1-Axis (wing leveler)?, 2 axis with altitude hold, or 3 axis with yaw dampener?, Compatibility with existing and future upgrades?

    In the end you arrive at the same answer everyone does:
    • GFC-700 or KAP-140 is G1000 only and you're stuck with what Cessna provides you
    • GFC-500 best overall retro-fit A/P which also required GI-275 or G5 EFIS
    • STEC 55x excellent if you already own one, but close in price to Garmin so why buy it new
    • STEC 20, 30, or Legacy Cessna A/P; add GPSS steering and use it it as a wing leveler until it breaks
    • 3100, is excellent and worth upgrading if already own the servo's installed from an earlier model
    If you don't want to track a heading (I know I do, easier to vector as directed)
    • TrueTrak or Trio are good lower cost options
    After ruling out GFC500, it's what compromises are you will to make balanced with what is already installed in the plane - in my opinion.
     
  7. asicer

    asicer Final Approach

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    TruTrak can now interface with an Aspen or G5 for heading. Trio has documented interfacing with Aspen or G5 for heading but it hasn't been approved yet.
     
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  8. NordicDave

    NordicDave Pattern Altitude PoA Supporter

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    If I had a G5, probably better to spend the extra $2K over the TruTrak for the GFC-500 kit. Worth noting B-K has bought TruTrak and it's now Bendix-King Aero Cruze 100. I REALLY wish B-K would get their act together as a competitor to Garmin, but they seem to have a keen corporate skill of shooting themselves in the foot and abandoning legacy customers.
     
  9. Katamarino

    Katamarino Cleared for Takeoff

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    How does the inbuilt autopilot in the G3X experimental compare to the GFC500, does anyone have experience?
     
  10. NordicDave

    NordicDave Pattern Altitude PoA Supporter

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    It's basically the same. The GFC-500 head unit is NOT the autopilot, it's just a control head to house the switches. The brains of the GFC-500 are in the G3X, G500, G5 all using the same code base; which was inherited from the GFC-700.

    The experimental versions of G3X and G5 lead in a few features which eventually trickle down to the certified G3X and G5.
     
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  11. WannFly

    WannFly Final Approach

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    looks like its for Exp only? the brain is same, you miss out of Level button and few other controls without the mode controller. from what i can tell anyway https://buy.garmin.com/en-US/US/p/607047
     
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  12. WannFly

    WannFly Final Approach

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    a couple of reviews including one from me on the GFC 500
    https://www.pilotsofamerica.com/com...installed-in-182q-and-it-is-fantastic.109745/

    https://www.pilotsofamerica.com/community/threads/review-gfc-500-in-a-pa-28-181.126607/

    since i wrote the above, i have about 80 more hours on the AP and it has worked flawlessly. I am in the process of developing a flow for engine out situation (depending on how high the fan stops) where you can just punch in Indicated airspeed hold of 72 kts (for me, yours would be diff), put on heading mode or Nav mode if airport is close by and let george fly the plane while i do rest of the stuff .. navigation, radio, troubleshooting, getting ready for a change of underwear etc.
     
  13. David Megginson

    David Megginson Cleared for Takeoff

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    Trio and TruTrack are not certified for IFR approaches, so if that's important to you, that washes them out.

    Most older autopilots like the Century depend on the attitude indicator, so if you have a vacuum failure, you lose your autopilot at the same time, when you would otherwise have needed it most.

    Second-gen A/Ps from a couple of decades ago, like the KAP 140 and the older S-TECs (e.g. the S-TEC 55x or my S-TEC 20) are rate-based. That makes them independent of the vacuum system, but they're slightly more sluggish in response than attitude-based A/Ps. They were the best option before AHRS for safety of flight. They're good enough for approaches, but you'll weave a tiny bit in strong or gusty winds, and sometimes overshoot a turn slightly.

    Modern third-generation A/Ps like the GFC 500, TruTrak/Aerocruze 100, Trio, S-TEC 3100, and Aerocruze 230 are digital AHRS-based. They're independent of the vacuum system, like the second-gen rate-based A/Ps, but have the faster responsiveness of the attitude-based A/Ps, so they're the best of both worlds (in a sense). If you're VFR only, the TruTrak/AeroCruze 100 or Trio will be the best deals. If you're IFR, you'll probably want an A/P that can legally fly coupled approaches, so the GFC 500 is the most-affordable option (if it's available for your plane).
     
    Last edited: Feb 22, 2021
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  14. TimRF79

    TimRF79 Pre-takeoff checklist

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    That is super helpful.
    What about the Avidyne DFC90, the website shows it for some 182s' as an 55x plug and play replacement.
     
  15. asicer

    asicer Final Approach

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    Actually, there's smarts in the servos too. It's a distributed system.
     
  16. David Megginson

    David Megginson Cleared for Takeoff

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    Not familiar, but I'd be shocked if it weren't also AHRS-based. Nobody would build anything else these days.

    FWIW, the S-TEC 3100 is not a slide-in replacement for the S-TEC 55X (I don't think), but you can still reuse your old servos and save some money.

    The Bendix-King AeroCruze 230 is a slide-in replacement for the KFC 150 and 200 (but not the 140).
     
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  17. wheaties

    wheaties Pre-takeoff checklist

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    Don't forget the GFC600 for twin planes coupled to a g500nxi. Makes engine out a bit safer.
     
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  18. CRQFlier

    CRQFlier Pre-takeoff checklist

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    Really wish the GFC500 didn't require the G5. I really dislike how small the screen is for the hsi. Argh.

    Sent from my SM-G960U1 using Tapatalk
     
  19. asicer

    asicer Final Approach

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    A G3x can substitute for the G5 :)
     
  20. CRQFlier

    CRQFlier Pre-takeoff checklist

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    Maybe G will sponsor me if I start YouTubing.

    Sent from my SM-G960U1 using Tapatalk
     
  21. AlleyCat67

    AlleyCat67 Pre-takeoff checklist

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    Just to say this thread has been extremely useful. Thinking of swapping out my old Century 1 and this is good info.
     
  22. TrueCourse

    TrueCourse Pre-takeoff checklist

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    Limited GFC500 experience so far, but impressed. With that said, the less capable autopilots that can’t shoot an approach, but with heading and altitude hold capabilities, will force you to keep your hand IFR flying skills sharper. It’s interesting that a certain level of automation is more than adequate, until a more capable system makes things easier.
     
  23. David Megginson

    David Megginson Cleared for Takeoff

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    Fully agree. It depends on the kind of IFR you do.
    • An enroute-only A/P will help reduce fatigue during the (say) 4 hours that you're just flying along in more-or-less a straight line, as well as during cruise climbs and descents.
    • An approach-certified A/P will relieve task saturation when you're at the end of that 4 hours, and suddenly have to juggle several things at once.
    I have only an older, single-axis rate-based A/P (the S-TEC 20, with the ST-901 GPSS converter), but it is approach-certified, and I've been extremely grateful for it at the end of a long, difficult flight in turbulence and low weather. I just dial the approach into my GPS, set throttle and trim, then monitor what it's doing, freeing up time for communicating with ATC, panel scan, pre-landing checks, etc etc. I personally would pay extra to keep that capability if I were upgrading.

    OTOH, if your IFR flying is mainly just popping up and down through a cloud layer, and you rarely or never fly when your destination is forecast to be IMC, then it probably wouldn't make sense to spend the extra few thousand for the GFC 500 — a less-expensive Bendix-King AeroCruze 100 (née TruTrak) will serve you just fine.
     
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  24. TrueCourse

    TrueCourse Pre-takeoff checklist

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    You mention S-TEC 20. I'll be flying an airplane with one of those soon. Supposedly this one it tracks heading, gps, nav, and has the altitude hold.
     
  25. David Megginson

    David Megginson Cleared for Takeoff

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    There are two different types of S-TEC 20 installations:

    A basic installation can keep the wings level or at a bank angle you choose (ST mode), chase your heading bug (HD mode), or try to keep your CDI centred gently (LO TRK mode) or aggressively (HI TRK mode). It doesn't know or care whether the CDI is being driven by a VOR receiver or a GPS. It can't intercept a course or fly a turn, so you do that with the heading bug, then go back to TRK when the CDI is nearly centred.

    A GPSS installation is a whole different beast. The ST-901 GPSS unit — or a Garmin G5 with GPSS support — intercepts the input for HD mode and gives you the option to follow the heading bug (like before) or take roll-steering instructions from the GPS. When you're in GPSS mode, the S-TEC 20 will fly holds, procedure turns, RNAV T-approaches, DME or RF arcs, or anything else you like.

    DM me with your email address if you'd like PDF copies of the S-TEC 20/30 manual (for a basic installation) and the ST-901 manual (for GPS steering).

    Cheers, David
     
  26. Deelee

    Deelee Cleared for Takeoff

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    wonder why the Trutrak isn't. I have seen reports of the TT coupling to an LPV and flying it to minimums. So it seems the AP is capable and is programmed to do it. Wonder why they never got it certified...
     
  27. David Megginson

    David Megginson Cleared for Takeoff

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    It would have cost them a lot more money, taken them a lot more time, and allowed them to certify for fewer aircraft models (at first). I've heard (but haven't confirmed) that Trio made the same choice.

    Certifying for enroute-only IFR allowed them to get the A/P to market faster, at a lower price—the FAA seems to have a much lower certification bar for A/Ps that won't be used in instrument approaches—so it wasn't necessarily a bad business decision. By getting to market fast and a low price, they got a lot of buzz, and sold a lot of units.

    TruTrak probably always honestly intended to go back and do the extra certification work later (and maybe charge extra for an "approach-certified" version to cover the costs), but then Bendix-King bought them and stuck them in their "cheap-VFR-autopilot" slot in the product line, while B-K was already pushing their not-very-popular developed-in-house AeroCruze 230 as their main IFR GPS for simpler planes, so it's possible (not verified) that they don't have any enthusiasm for making the AeroCruze 100/TruTrak into an internal competitor.
     
  28. TrueCourse

    TrueCourse Pre-takeoff checklist

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    Thanks for the offer. I just realized its an S-TEC 30 and I believe it does have GPSS.
     
  29. David Megginson

    David Megginson Cleared for Takeoff

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    Excellent! The only difference with the S-TEC 30 is that it also has altitude hold. It can't fly a glideslope or handle a climb/descent, though.

    Same manual for the S-TEC 20/30.
     
    Last edited: Feb 23, 2021