Garmin GFC 500 Autopilot Flight Overview

[Niko182]

27 minutes ago, Oscar Avalle said:

Aspen can drive de autopilot?

 

Nope. It works with a g5 as your backup to the aspen, but then the entire system is a bit funky.

[Rmag]

5 hours ago, Oscar Avalle said:

Aspen can drive de autopilot?

No

[PT20J]

The Garmin autopilot is a completely different architecture than other autopilots. With a Bendix King or S-TEC, there is a computer that gets inputs from the attitude indicator and controls the servos.  In the GFC 500, the control panel is not the autopilot computer. It’s just a control panel. (It also has the audio functions and some monitoring circuitry.) Most of the autopilot logic is built into the attitude indicator — some is in the servos. That’s why it only works with Garmin devices that contain the autopilot logic (G5, G3X, GI275). 

Skip

[William Munney]

I know it’s an old thread but still a very good video.  And, the GFC 500 isn’t going anywhere.  In fact, I am having one installed next month in the Ovation.

A few things from some experience with auto flight systems:

If you have the TO/GA button (Pronounced “toe-guh”) you should use it for takeoff in  (TO/TO) to a safe altitude before you select your roll and pitch modes.  Especially during a low visibility takeoff.  What is safe?  Probably 500-1000’ above the airport.  ATC understands this.  You activate the TO/GA button as you apply takeoff power.  You are essentially commanding wings level and a pre programmed pitch attitude to the safe altitude before selecting your roll and pitch modes.

On the go-around the sequence is to press the TO/GA button as you add go-around power commanding the autopilot roll and pitch modes to GA/GA (wings level and a pre-programmed pitch attitude)…..at positive rate, select gear up……then cleanup the aircraft.  At a safe altitude, select GPS sequencing and then select your desired roll and pitch modes.

You do not want to be goofing around with autopilot modes close to the ground.  Select TO or GA as needed and fly the command bars to a safe altitude before selecting other modes.

VNAV makes life great if you know how to use it.  Practice VFR first.  Also, VNAV on the GFC500 only works to the FAF.

Use APPCH for approaches with vertical guidance:  LPV, LP+V, LNAV/VNAV, LNAV+V, ILS.  I think the visual approach’s in the GTN works too.

Use NAV for approaches with no vertical guidance.

When you are “cleared for the approach”, you can select APPCH (for approaches with vertical guidance).  This arms the approach to become active when parameters are met.  Be VERY careful NOT to select APPCH for an ILS unless you are within the service volumes for the localizer and glideslope.  False localizers and glideslopes are possible.

Every time you select an altitude, or a roll or pitch mode on the GFC 507 autopilot control head, you MUST verify your selection on the FMA’s (Flight Mode Annunciators…..or, the “scoreboard”) because THAT is what the autopilot will fly.  DO IT EVERY TIME.  More than a few aircraft have been lost because of autopilot mode confusion.  If the autopilot is doing something you don’t understand turn it off and fly the airplane.  There are NO EXCEPTIONS to this rule.

 
DO NOT just push buttons and watch the autopilot to see what it will do.  Know what modes you are in and what modes are armed and anticipate the changes to the FMA’s before they happen so you can anticipate what the autopilot should be doing before it does it.  You will then know immediately if it’s not doing what it’s supposed to be doing.

Finally, flying airplanes on automation is a separate and important skill from hand flying airplanes.  It requires a lot of study and practice as your job is now translating ATC instructions into commands that the autopilot understands.  Ultimately, you should be able to engage the automation a few hundred feet after takeoff, fly to your destination on automation and disengage it a few hundred feet from landing.  After you can do this, use it at your discretion.  

Autopilots can be a powerful safety tool or another very real danger in the cockpit depending on the user.

Hope this helps someone.

[Z W]

Nice post.

I don't like to use the TO/GO for a normal takeoff though. The attitude it provides to give Vx, while what you want on a go-around in IMC, is too nose-high for a normal departure.  It also then requires that you re-configure the autopilot entirely for your first turn - You must press HDG or NAV, then VS or IAS, then dial in your preferred VS or IAS on the wheel, then press "AP", all while possibly bumping around, entering IMC, talking to ATC, etc.

Instead I prefer to configure the autopilot to fly my planned departure, which means flight director on, heading mode engaged, heading set to runway heading, vertical speed set to 500+ FPM, altitude bug set. This allows me to follow the flight director and heading bug on takeoff manually until 500 feet AGL, then engage the autopilot and be fully configured just by pressing the "AP" button.  Also passing 500 feet AGL I will roll the heading bug over to my assigned heading, or enter NAV mode to go on-course, whichever is appropriate.

An alternative to this is instead of HDG, to leave it in ROL mode, and pre-set your heading bug to your assigned heading if you have one. So when you begin your first turn and press the AP button, you just also press HDG and you're configured and don't have to remember what your assigned heading was during takeoff. This maybe works better and removes one item you have to remember (your assigned heading), but I like having the heading bug available to follow to fly runway heading, in addition to the flight director, which in this scenario is not actually tracking runway heading.

So for me, the TO/GO is more of a GO button. But I'm curious to hear if anyone sees issues with what I've developed above as my practice or does it differently.

A note - I had to add each of the autopilot configuration steps to my pre-taxi checklist to start getting it all right, after the GFC500 was installed. Highly recommend that to anyone learning this new autopilot - there are a lot of configurations you can make on the ground to make your life easier right after takeoff.

[midlifeflyer]

7 hours ago, Z W said:

don't like to use the TO/GO for a normal takeoff though. The attitude it provides to give Vx,

It does? Do you have a reference for that? (If I have it, I use it for all takeoffs - one less thing to forget when its needed). 

If so, I'm trying to make sense why. Primary use is a missed approach and I can't see a need for Vx. 

In terms of "differently, TOGA is my initial climb. My heading bug and altitude are pre-set. If it's a straight ahead initial climb beyond the altitude limitation, I engage the AP in TOGA mode.  HDG (or NAV as appropriate)  mode (whether Flight Director or full AP) comes at the point when I am going to turn. The basic TOGA climb is comfortable enough that switching to IAS/FLC is the last step.

I agree completely with a mini-checklist at least at the beginning. I don't, but that's only because my engagement sequence is pretty much the same regardless of equipment - I even engage old autopilots in their default mode before switching to HDG/NAV and climb.

[Marc_B]

In my aircraft with GFC500, it seems that the pitch for TOGA is somewhere between Vx and Vy and closer to best glide coincidentally.

If anyone is aware of design intentions or how Garmin determined default pitch for the airframe I’d love to learn more!

but TOGA is a mode meant to get away from the ground and not a “flying” mode…meaning I quickly switch to a IAS mode for climb in the climb out. 

[Z W]

The AFM supplement for the GFC500 for a M20M (shown below) says TOGA establishes a 7 degree nose up pitch. I thought I had a scan of mine but can't find it right now.

Calling it Vx was inaccurate on my part, although I believe it produces performance close to that at full power, but I do know it is referencing pitch, not airspeed.

In my plane it's enough nose up pitch to startle passengers who are not expecting it and is more nose up pitch than I like to use on a standard climb-out for sure.

[midlifeflyer]

13 minutes ago, Z W said:

The AFM supplement for the GFC500 for a M20M (shown below) says TOGA establishes a 7 degree nose up pitch. I thought I had a scan of mine but can't find it right now.

Calling it Vx was inaccurate on my part, although I believe it produces performance close to that at full power, but I do know it is referencing pitch, not airspeed.

In my plane it's enough nose up pitch to startle passengers who are not expecting it and is more nose up pitch than I like to use on a standard climb-out for sure.

 

Yes, I know it's 7 degrees. That seems to be fairly standard across many light GA aircraft makes and models.  

I don't know what it ends up doing in a Bravo, but I've been using 7 to 10 degrees for a basic departure climb is almost all of the 30+ makes and models I've flown over the past 3 decades.  Mostly curious at this point.

[Mooney in Oz]

19 hours ago, William Munney said:

Ultimately, you should be able to engage the automation a few hundred feet after takeoff

A very well written post and thank you for it. Just one matter - From the AFMS Limitations section -

The autopilot must be disengaged below 800 feet AGL for all operations other than approach operations.

I interpret this as the AP must not be engaged until above 800 feet.

The only exemption to this I believe is engaging the YD as there is nothing to say you can’t and it can be operated independent of the AP.

[PT20J]

In my M20J, TOGA (the GFC 500 STC actually calls for the button to be labelled GO AROUND) commands a 7 degree pitch up which works out to about 95 KIAS at sea level. Vx is 66 KIAS and Vy is 86 KIAS. I need 12 degrees to get Vx and about 10 degrees for Vy. 

I select TOGA and HDG with the runway heading bugged before takeoff. If I flew without the FD, I would take off and pitch to 7 deg and that's what I like the FD to command. But, I like it in HDG so I can just turn the bug to the first heading without changing modes. And, yes I wait until above 800 ft to engage the AP.

[Z W]

Well, I will double-check my installation then. Makes me wonder if my TOGA is set higher than 7 degrees.

[midlifeflyer]

15 hours ago, PT20J said:

In my M20J, TOGA (the GFC 500 STC actually calls for the button to be labelled GO AROUND) commands a 7 degree pitch up which works out to about 95 KIAS at sea level. Vx is 66 KIAS and Vy is 86 KIAS. I need 12 degrees to get Vx and about 10 degrees for Vy. 

Yes, that's what I've been seeing in various makes and models. More like a cruise climb than a Vx or Vy climb. 

[William Munney]

My install is not complete as of today so I have only read a generic GFC 500 POH supplement.  The pitch attitude for TO/GA is configured during the installation for make and model.  I don’t know if the lawyers will allow the install techs to change this for user preference.  But, i do know that this is supposed to be a “TO/GA” button.  (Takeoff/Go-around).

All modern flight decks incorporate a version of TO/GA.  It is designed to get you to away from the ground to a safe altitude before you engage the autopilot. Same principle on the go-around.  Pitch and roll modes are NOT selected until after the minimum safe altitude.  You are not prohibited from pitching less/ more than the command bars as the situation or personal preference dictates.  The FD command bars shows you what the AP will do if engaged and also provide a target reference when you are hand flying IF you want them,  NEVER become a slave to the FD command bars.  I have flown with people that would turn the airplane upside down and pull if that’s what the FD bars commanded.

The sequence of events should be:

TO/GA button selected at the start of the takeoff roll;  fly wings level and a pre-programmed pitch to the minimum AP engagement height; select AP ON; select a ROLL mode and verify the FMA’s and performance; select a PITCH mode and verify FMA’s and performance.

Doing the above also makes every takeoff the same from an automation point of view and every go-around identical to a takeoff…… but initiated at minimums instead of at the runway.

Selecting other roll and pitch modes on the ground is unnecessarily complicated and could be dangerous.  No airline I have ever worked at recommends this.  Takeoffs during low IFR conditions are busy.  IF you are going to use the automation it’s best to keep it simple near the ground. (TO/GA).  As for pre-selecting modes other than TO/GA for take off because you feel overloaded otherwise………AVIATE, NAVIGATE, COMMUNICATE……in that order.  And, slow down.  ATC only pushes you as fast as you will let them.  The rest of the “pressure” is self-imposed.

Merry Christmas all.

Edited December 23, 2024 by William Munney

[midlifeflyer]

4 hours ago, William Munney said:

The sequence of events should be:

TO/GA button selected at the start of the takeoff roll;  fly wings level and a pre-programmed pitch to the minimum AP engagement height; select AP ON; select a ROLL mode and verify the FMA’s and performance; select a PITCH mode and verify FMA’s and performance.

Is this opinion or is there a verifiable reference for “should”? 

(I don’t disagree. It’s what I do and teach. )

[PT20J]

There are reasonable differences between two pilot crew procedures and single pilot procedures.

[Marc_B]

I don’t think I’ve ever been instructed to push TOGA on takeoff roll and that’s not how I use the AP.  Most of the time I get “fly runway heading” or “turn heading…” for an instrument departure.  For me (typically single pilot IFR) I set up as much as I can on the ground when I get my clearance and I’m programming GPS.

Hand fly till 800 ft and by then I’m either on a heading or already direct to a fix.

Rather than TOGA most of the time I use IAS for climb and HDG for initial lateral mode.  Sometimes i push TOGA, dial in heading bug and press HDG and leave pitch on TO. 

[midlifeflyer]

On 4/20/2021 at 12:33 PM, flysamo said:

never knew TOGO could be used on take off

All it’s doing is giving you a FD picture for a normal climb. So why do you think it couldn’t.  

While it’s not necessary and some don’t teach it for takeoff, others do because consistency builds a habit that makes it less likely you will forget it when you need it. This is especially true with new equipment but it applies to many flight operations.

My flying club has an airplane with TOGA. When I do checkouts or recurrent training, I see lots of pilots who don’t use it for takeoff. Most of them don’t use it for a go-around or missed approach either. Debrief:

Me: any reason you didn’t use the TOGA in that go-around/missed approach?

They: I forgot.

[Marc_B]

@midlifeflyer interesting that the AFMS says basically nothing about TO. How do you typically teach programming and using AP leading up to and at takeoff?

Curious where press the button as you advance throttle came from and if you use that practice?  Certainly understand that with GA…

[midlifeflyer]

1 hour ago, Marc_B said:

@midlifeflyer interesting that the AFMS says basically nothing about TO. How do you typically teach programming and using AP leading up to and at takeoff?

Curious where press the button as you advance throttle came from and if you use that practice?  Certainly understand that with GA…

@William Munney and I use the same sequence.

After startup

• Flight plan entered
• Altitude and initial heading bugged

Before takeoff

• TOGA pressed.

After takeoff - ≥ 800 AGL

• AP engaged
• HDG mode
• Climb mode

There is at least one modification. On an IFR departure with an initial turn  below 800', the switch to HDG mode will come earlier and before AP engagement.

To answer your other question, press the button as you advance throttle is kind of what you want to do in the go-around/missed approach situation where the initial climb is (almost) invariably straight ahead.  But it  may have its rom the G1000./GFC700 combo. If the aircraft uses a lever throttle, the TOGA button is often integrated into the throttle (DA40 pic). With a vernier throttle you can just stick out your thumb as you throttle up (C182 pic). Ideally an aftermarket install of a GFC 500 or 600 will place it in that kind of position, but I know that's not always the case.  I just do it as one of the last pretakeoff items at the hold short line.  With the variety if aircraft I fly, it just makes more sense for me.

 

[Fly Boomer]

On 4/20/2021 at 11:33 AM, flysamo said:

never knew TOGO could be used on take off

I don't know if anyone does, or if it's legal, or if it's a good idea, but TO is an abbreviation for TakeOff, and GA is an abbreviation for Go Around.  Hence TOGA or TO/GA.

[Pinecone]

59 minutes ago, midlifeflyer said:

@William Munney and I use the same sequence.

After startup

• Flight plan entered
• Altitude and initial heading bugged

Before takeoff

• TOGA pressed.

After takeoff - ≥ 800 AGL

• AP engaged
• HDG mode
• Climb mode

There is at least one modification. On an IFR departure with an initial turn  below 800', the switch to HDG mode will come earlier and before AP engagement.

To answer your other question, press the button as you advance throttle is kind of what you want to do in the go-around/missed approach situation where the initial climb is (almost) invariably straight ahead.  But it  may have its rom the G1000./GFC700 combo. If the aircraft uses a lever throttle, the TOGA button is often integrated into the throttle (DA40 pic). With a vernier throttle you can just stick out your thumb as you throttle up (C182 pic). Ideally an aftermarket install of a GFC 500 or 600 will place it in that kind of position, but I know that's not always the case.  I just do it as one of the last pretakeoff items at the hold short line.  With the variety if aircraft I fly, it just makes more sense for me.

  

Mine  Easy to extend thumb and hit it when advancing the throttle.   Guard was 3D printed by a friend.

 

[midlifeflyer]

6 minutes ago, Fly Boomer said:

I don't know if anyone does, or if it's legal, or if it's a good idea, but TO is an abbreviation for TakeOff, and GA is an abbreviation for Go Around.  Hence TOGA or TO/GA.

Yes, people do. And many think it's an excellent technique. That's a matter of personal preference. 

But why do you think it might not be legal to have command bars displaying a 7 degree departure pitch attitude on an attitude indicator?

 

[Fly Boomer]

1 minute ago, midlifeflyer said:

Yes, people do.

But why do you think it might not be legal to have command bars displaying a 7 degree departure pitch attitude on an attitude indicator?

 

Check out my response above.

[midlifeflyer]

1 minute ago, Fly Boomer said:

Check out my response above.

Dunno. I see two posts by you in this thread and neither talks about why your think it might not be legal.