Experience operating Garmin GFC 500 in M20C

[Ragsf15e]

4 hours ago, kortopates said:

Exactly, you don't necessarily have to click on "Activate Approach" or "Activate VTF". You can just as easily go into the flight plan, scroll down to the approach portion and either do a Direct To approach waypoint, or make any leg there the active leg.

This is actually the most common way to activate the approach because it allow activating it on a leg your being vectored on to (which is the way every NPA should be flown) or activating with a waypoint other than the IAF or first waypoint in the approach (which could be an IAF or Feeder route VOR). I would only advocate using VTF on a PA because with a glide slope you no longer care about step down fixes; only verifying you crossed the FAF at the charted altitude.

PA- precision Approach, NPA- Non-precision Approach  

I’m just saying this because you didn’t draw the distinction above and it can become dangerous, I know you know this pitfall, but you’ve got to be careful saying it… if you load an approach (say on radar vectors) and then enter direct to the FAF (as you say “just go Direct to an approach waypoint”), your hsi will center up and give you steering direct to the faf.  You will also have distance to the faf.  It can very easily look like you’re “established on the approach” when in fact you’re way off of the course into the faf.  Depending on clearance, I have seen people descend to faf altitude because it looks very much like they are established.

Using vtf or activating the leg into the faf are much better.

[kortopates]

I’m just saying this because you didn’t draw the distinction above and it can become dangerous, I know you know this pitfall, but you’ve got to be careful saying it… if you load an approach (say on radar vectors) and then enter direct to the FAF (as you say “just go Direct to an approach waypoint”), your hsi will center up and give you steering direct to the faf.  You will also have distance to the faf.  It can very easily look like you’re “established on the approach” when in fact you’re way off of the course into the faf.  Depending on clearance, I have seen people descend to faf altitude because it looks very much like they are established.
Using vtf or activating the leg into the faf are much better.

Yep, direct to an approach fix is only safe when the controller tell you that which only be for an IAF or IF, never the FAF.


Sent from my iPhone using Tapatalk

[rbp]

4 hours ago, Vance Harral said:

it's my position that you're always subject to last-minute changes to your approach plan

sure, 100%.  different runway/approach? sure, if you have time just load it in,  or break off the approach, get a delay vector and reprogram.   get a clearance to a different fix on the current approach? sure, its right there in the flight plan -- activate the leg or hit D.

the issue with activating VTF is that it is not simply subjecting you to a possible 'late-in-the game change' -- activating VTF removes fixes from an approach that are in front of you (not behind you) on an approach that you are already in the middle of flying, and at the latest stage possible: heading towards final. do you really want to be at 2000 ft heading to intercept the final approach course, be given direct another fix that's no longer in your flight plan, and have to reprogram the approach? Thanks, i'll leave the approach in flight plan in.

this is moot for me anyway, as I now have a GTN

[Vance Harral]

17 hours ago, rbp said:

do you really want to be at 2000 ft heading to intercept the final approach course, be given direct another fix that's no longer in your flight plan, and have to reprogram the approach?

No, I don't want that, but I have had to deal with that, and have become proficient in doing so as part of the larger skill of rapid navigator reprogramming.

In the scenario you're describing, the fix you've been cleared to - the one that's no longer in your flight plan because you loaded VTF - must have been a fix prior to the FAF, because the FAF is never deleted from the flight plan with VTF, in any version of any navigator software.  In other words, it's either an IAF or an IF.  It's my position that being asked to reload an approach when you are still approaching an IAF or IF for that approach, is not a crisis, and should be a tool in your tool bag.  When fixing the VTF problem, the approach you have to reload is the same approach you've already loaded, just with a different transition.  So it's not like you have to select a different airport or a different approach, just a different transition.  If you can't do this in the space of a few seconds with a GTN or IFD, or even with an older GNS, then I respectfully submit you could use some more practice.

Again, I want to be really clear that I'm not advocating pilots load VTF as a matter of course, contrary to the AIM guidance.  What I am saying is that fixing the VTF problem isn't any more difficult or time consuming than fixing other types of problems you're going to run into, regardless of your position on whether you ever load VTF.

[kortopates]

On 11/11/2022 at 6:52 PM, rbp said:

do you really want to be at 2000 ft heading to intercept the final approach course, be given direct another fix that's no longer in your flight plan, and have to reprogram the approach? Thanks, i'll leave the approach in flight plan in.

Make sure you're not creating unnecessary workload with last minute changes as well. If this is a precision approach, I'll maintain that in the vast majority of times you don't need to update the flight plan because the controller caught you off guard and said "direct to XYZ IF (if it was direct to the IAF you're not on Vectors to final) as well as cleared for the approach, maintain 2000' until established.  Given its a precision approach, just maintain an intercept angle onto Final and you know that soon as you are established, wait for the GS to come down to you before descending and you have nothing to worry about.

About the only I could imagine taking the time to reprogram the approach leg is if the controller said" Direct to XYZ IF, cleared for the approach, maintain 2000' until crossing XYZ". Now I do need XYZ because we can't rely on the map to tell when we've crossed XYZ. But still I have never gotten such an approach clearance on a PA in all my instrument years.   

[rbp]

On 11/12/2022 at 3:13 PM, Vance Harral said:

fixing the VTF problem isn't any more difficult or time consuming than fixing other types of problems you're going to run into

ok, maybe i wasn't clear -- its not that its more difficult -- its the point in time when its happening.

at some point during the flight, I come down to doing only one of two things: continuing the approach to a landing or going missed. anything else happening in the airplane (navigator, configuration, radios, seat back tray tables, chit chat, etc) has to wait until I'm out of a critical phase of flight. maybe that point in time comes later in the approach for you than it does for me, but I'm OK with that. its a kind of "personal minimum" for me

[DGates]

I have (or will have, long story) a GFC500 in a 1965 M20C.  I did not have the auto trim option installed.  Does anyone have operational experience in a GFC500 install without the trim option?  I assume I will get "trim up // trim down" messages and I would adjust the trim appropriately.  How much of a PITA is that in operational practice? 

 

The long story:  I got the plane painted, then moved it to the avionics shop.  The GFC500 install was completed short of the servos themselves, supply chain backorder and the shop placed the order late due to an oversight.  I took delivery of the finished avionics install that included dual GI-275's, replacement comm2, and a EI CGR30 C&P combo engine monitor.  All finished ... except for the GFC500 servos.  This is the status now, I got to fly the plane for two weeks before departing on a one year deployment assignment to Korea, which is where I am now. The end result is I have yet to experience all that GFC500 goodness in MY plane, though I have used a GFC500 a fair bit in a Cirrus SR20, I know it's gonna be pretty cool.  

I have the option of spending a few additional AMU's and go ahead and purchase the trim servo option, probably a quick and easy install, when I return from Korea and my bank account has a chance to get refilled with AMU's.  Interested in pro's and con's of doing so?  I mean, trimming by hand isn't that hard, right?  I'm on the fence regarding ordering the trim option.  

 

Thoughts?

[kortopates]

Just now, DGates said:

I have (or will have, long story) a GFC500 in a 1965 M20C.  I did not have the auto trim option installed.  Does anyone have operational experience in a GFC500 install without the trim option?  I assume I will get "trim up // trim down" messages and I would adjust the trim appropriately.  How much of a PITA is that in operational practice? 

 

The long story:  I got the plane painted, then moved it to the avionics shop.  The GFC500 install was completed short of the servos themselves, supply chain backorder and the shop placed the order late due to an oversight.  I took delivery of the finished avionics install that included dual GI-275's, replacement comm2, and a EI CGR30 C&P combo engine monitor.  All finished ... except for the GFC500 servos.  This is the status now, I got to fly the plane for two weeks before departing on a one year deployment assignment to Korea, which is where I am now. The end result is I have yet to experience all that GFC500 goodness in MY plane, though I have used a GFC500 a fair bit in a Cirrus SR20, I know it's gonna be pretty cool.  

I have the option of spending a few additional AMU's and go ahead and purchase the trim servo option, probably a quick and easy install, when I return from Korea and my bank account has a chance to get refilled with AMU's.  Interested in pro's and con's of doing so?  I mean, trimming by hand isn't that hard, right?  I'm on the fence regarding ordering the trim option.  

 

Thoughts?

 Lots of experience in C172's simply because its a makes for a much cheaper 2-axis auto-pilot install. But I haven't experienced that in a Mooney yet. But, yes, if your changing speed, or speed and altitude, you'll get messages to trim manually and if not done fairly quickly, the autopilot will simply disconnect. The messages are quite obvious and I shouldn't imply you have little time to correct trim, just don't ignore the messages.

Adding the electric trim isn't trivial, but not hard, but every servo is considerable work yet this is tied to switch on the yoke. 

Certainly takes away from the experience of seeing the AP control the plane entirely, including a procedure turn or course reversal and VNAV descents without any help from you other than loading approaches and perhaps adding altitude constraints for VNAV.

There is certainly no con's in completing the install beyond time and money.  

[Ragsf15e]

36 minutes ago, DGates said:

I have (or will have, long story) a GFC500 in a 1965 M20C.  I did not have the auto trim option installed.  Does anyone have operational experience in a GFC500 install without the trim option?  I assume I will get "trim up // trim down" messages and I would adjust the trim appropriately.  How much of a PITA is that in operational practice? 

 

The long story:  I got the plane painted, then moved it to the avionics shop.  The GFC500 install was completed short of the servos themselves, supply chain backorder and the shop placed the order late due to an oversight.  I took delivery of the finished avionics install that included dual GI-275's, replacement comm2, and a EI CGR30 C&P combo engine monitor.  All finished ... except for the GFC500 servos.  This is the status now, I got to fly the plane for two weeks before departing on a one year deployment assignment to Korea, which is where I am now. The end result is I have yet to experience all that GFC500 goodness in MY plane, though I have used a GFC500 a fair bit in a Cirrus SR20, I know it's gonna be pretty cool.  

I have the option of spending a few additional AMU's and go ahead and purchase the trim servo option, probably a quick and easy install, when I return from Korea and my bank account has a chance to get refilled with AMU's.  Interested in pro's and con's of doing so?  I mean, trimming by hand isn't that hard, right?  I'm on the fence regarding ordering the trim option.  

 

Thoughts?

I currently have an stec 30a which is 2 axis, no trim.  It annunciates required trim similarly.  

If you just want to use the airplane for long vfr cross country and the occasional approach, it’s fine without the auto trim.  Thats how I use my airplane, and it’s just fine to help out in occasional ifr / imc.  If you use it in imc a lot and fly a reasonable number of approaches and use it in busy airspace, I’d get the auto trim and give yourself one less thing to worry about.

[MikeOH]

2 hours ago, DGates said:

I have (or will have, long story) a GFC500 in a 1965 M20C.  I did not have the auto trim option installed.  Does anyone have operational experience in a GFC500 install without the trim option?  I assume I will get "trim up // trim down" messages and I would adjust the trim appropriately.  How much of a PITA is that in operational practice? 

 

The long story:  I got the plane painted, then moved it to the avionics shop.  The GFC500 install was completed short of the servos themselves, supply chain backorder and the shop placed the order late due to an oversight.  I took delivery of the finished avionics install that included dual GI-275's, replacement comm2, and a EI CGR30 C&P combo engine monitor.  All finished ... except for the GFC500 servos.  This is the status now, I got to fly the plane for two weeks before departing on a one year deployment assignment to Korea, which is where I am now. The end result is I have yet to experience all that GFC500 goodness in MY plane, though I have used a GFC500 a fair bit in a Cirrus SR20, I know it's gonna be pretty cool.  

I have the option of spending a few additional AMU's and go ahead and purchase the trim servo option, probably a quick and easy install, when I return from Korea and my bank account has a chance to get refilled with AMU's.  Interested in pro's and con's of doing so?  I mean, trimming by hand isn't that hard, right?  I'm on the fence regarding ordering the trim option.  

 

Thoughts?

Like Rags I have an STEC-30 with altitude hold and NO auto/electric trim.  It's never been a big deal to me to trim when it tells me; nor has it ever disconnected because I waited too long.  Frankly, I like the fact I can NEVER have a trim runaway occur.  IFR I'm trimmed for speed before the FAF, so I drop the gear, disengage alt hold, and come on down adjusting power as needed; very little messing with the trim required until slowing for landing.

[Van Lanier]

Gents, 

Many thanks for the replies, insights, and recommendations regarding the GFC 500 and LPV approaches.  There is a lot of know-how in this group, and I appreciate you sharing it.  There is clearly a mind shift (and some serious training) required to safely and effectively using the GFC500, but that's the fun of mastering new technology.  Pressing on. 

[davesly]

On 11/9/2022 at 2:42 PM, Greg Ellis said:

I have some experience with the autopilot in my 63 C model but I have not been able to fly it very often.  Plane has been in the shop for its annual and a cylinder overhaul.  I'm still learning on it.  It flew great to and from Oshkosh this summer.  

It is a great autopilot and handles the plane well even in moderate turbulence.  @Skates97 has quite a bit of flight time in his and may be able to chime in a little more than I can.

Greg,

   Did you need to update your ailerons?  I have a 1962 and it seems there is no STC for pre-1965 M20C's

[davesly]

8 minutes ago, davesly said:

Greg,

   Did you need to update your ailerons?  I have a 1962 and it seems there is no STC for pre-1965 M20C's

https://www.garmin.com/en-US/newsroom/press-release/aviation/garmin-receives-additional-gfc-500-autopilot-certifications-3/

I just noticed that there was a recent (2021) AD that now covers pre-1965.  I assume this means I do not need to replace my ailerons.

 

[Greg Ellis]

12 hours ago, davesly said:

https://www.garmin.com/en-US/newsroom/press-release/aviation/garmin-receives-additional-gfc-500-autopilot-certifications-3/

I just noticed that there was a recent (2021) AD that now covers pre-1965.  I assume this means I do not need to replace my ailerons.

 

I did not have to replace my ailerons.  Nor should you.  Look at the supported aircraft which includes the 1962 C model.

https://www.garmin.com/en-US/p/604257#additional