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Experience operating Garmin GFC 500 in M20C


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If you have a Garmin GFC 500 in your M20C, I would appreciate knowing your tips, tricks, "gotchas," or other useful suggestions on safely operating this autopilot in a short-body Mooney.  Of particular concern is the auto-trim and system management best practices.  

Most of my flights are about 500 NM in light to moderate IMC on the East Coast.  I've been hand flying for 53 years, but it's past time for some backup.  I would have preferred a simpler autopilot with altitude hold and GPSS.  Alas, the S-Tec 30 is no more and it seems the GFC 500 is the new box in town.  So, how best to manage this beast?   

Many thanks. 

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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.

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2 hours ago, Van Lanier said:

If you have a Garmin GFC 500 in your M20C, I would appreciate knowing your tips, tricks, "gotchas," or other useful suggestions on safely operating this autopilot in a short-body Mooney.  Of particular concern is the auto-trim and system management best practices.  

Most of my flights are about 500 NM in light to moderate IMC on the East Coast.  I've been hand flying for 53 years, but it's past time for some backup.  I would have preferred a simpler autopilot with altitude hold and GPSS.  Alas, the S-Tec 30 is no more and it seems the GFC 500 is the new box in town.  So, how best to manage this beast?   

Many thanks. 

It's a great auto-pilot, and there are others with much more experience than I have, but here's a few things. Part of it depends on what kind of NAV you have in the plane. Most of these are not groundbreaking.

  • I use IAS climbs and VS descents to make sure I don't get too slow in a climb. Some pilots have had issues with oscillations in IAS mode and have documented it here on MS. When you push the IAS button it sets the climb to your current IAS. Instead of making a quick change to the target IAS, (say I'm level with an IAS of 140 but want to climb at 120) I wait a couple seconds and then use the dial to change it slowly and I haven't had the oscillation issue. 
  • Before TO I will set it to either my cruising altitude or first assigned altitude.
  • Before TO if I have been assigned a heading after departure I will set it to that, or if nothing assigned I set it to runway heading.
  • Biggest "gotcha" occurred when in GPS mode following a flight plan and ATC either gives you a heading to fly or a xx° turn. Before pressing the HDG button to switch to heading mode, push on the heading knob to set it to your current heading, then switch to HDG mode. If not the second you press HDG it is going to start a turn to whatever you had the bug set to last.
  • This is dependent on your NAV. If you have an approach loaded and you activate the approach it is going to turn you to the first point in the loaded approach. Typically here in SoCal it is always vectors to intercept, so I won't activate the approach in my NAV until I make sure the leg I am intercepting is the active on in my NAV.
  • It may never happen to you, but I have had a couple times I reached for something and my arm bumped the TO/GA button which caused the plane to start a pitch up. The first time I thought "What the heck is it doing?" Which brings me to my last one.
  • This goes for all auto pilots, but if it ever starts doing something unexpected just press the disconnect button, then figure out what it is doing. 
  • If you are set up so that it will fly a coupled approach from your NAV, you need to be below glideslope when you engage APR mode for it to intercept and follow it down. If you are above it is just going to keep flying you right along your merry way without descending.
  • The auto-trim is great, if I am hand flying an approach it makes it simple to make very small corrections to pitch without taking my right hand off the throttle.
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Van - great question, I’m glad you asked it.  I’m about to embark in the GFC 500 M20C experience myself and had similar questions. 
 

Skates - great descriptions and recommendations.  Thank you for sharing them.  
 

for those who also have experience with the GFC 500 has yours ever started unnecessarily adjusting trim?  I used an older auto-pilot that periodically decided to start trimming for no apparent reason.  More of a pain than a problem but annoying none the less.   

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6 minutes ago, S.C. said:

Van - great question, I’m glad you asked it.  I’m about to embark in the GFC 500 M20C experience myself and had similar questions. 
 

Skates - great descriptions and recommendations.  Thank you for sharing them.  
 

for those who also have experience with the GFC 500 has yours ever started unnecessarily adjusting trim?  I used an older auto-pilot that periodically decided to start trimming for no apparent reason.  More of a pain than a problem but annoying none the less.   

My GFC500 has never unnecessarily adjusted trim.  I have only had one issue with the GFC500 and it was an install problem and not a problem with the autopilot itself.  It was an electrical issue.  In my time using the GFC500 it has never done anything that I did not intentionally or accidentally tell it to do.  Most of the time it is an issue with me not programming or using the navigator, the autopilot was following, correctly.  The GFC500 has always done what I have told it to do.  If it does something wrong it was usually my fault, not the autopilot.

All of the advice given by @Skates97 is excellent advice.  I will add, that prior to takeoff, when lined up on the runway I make sure to push the HDG button on the autopilot to reset the heading bug to runway heading.  I also push the TO/GA button to set the flight director at a good departure attitude for climb especially if departing into IMC.

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I suspect at least some of the issues people have experienced are due to control friction. The GFC 500 servos seem more sensitive to this than legacy autopilots.

it’s common for Mooney elevator controls to have friction especially where the control shafts pass through the panel. Mooney has used at least three different designs for this bearing over the years, so they must be trying to get it right.

It is also not uncommon for the trim system to get stiff. The trim servo has to meet a trim rate specification and to do this Garmin uses a pretty large gear ratio on the chain drive which reduces the available torque.

Taking care to remediate any control friction issues before installation would be a good idea.

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4 hours ago, S.C. said:

for those who also have experience with the GFC 500 has yours ever started unnecessarily adjusting trim?  I used an older auto-pilot that periodically decided to start trimming for no apparent reason.  More of a pain than a problem but annoying none the less.   

I have not had mine do this. Like @Greg Ellis said, I haven't had it do anything that I haven't told it to do. Whenever it has started doing something I didn't want I disconnect it and eventually figure out what I had done or not done.

4 hours ago, Greg Ellis said:

I also push the TO/GA button to set the flight director at a good departure attitude for climb especially if departing into IMC.

Good point, I forgot to mention this, I do the same thing. It helps to have those little bars as reference.

Another thing to add for those getting it installed, they disconnect the universal joint on the trim tube just inside the avionics bay to put the gear on the tube for the auto-trim. When mine was done someone inadvertently turned the tube so when it was reconnected it was wrong. I found out when I was going through pre-flight and didn't have full travel of the trim. It was an easy fix, but could have been bad if I hadn't caught it before taking off. @PT20J suggested in another thread to have the installer run it all the way to one of the stops prior to disconnecting the joint.

 

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17 hours ago, Skates97 said:

It's a great auto-pilot, and there are others with much more experience than I have, but here's a few things. Part of it depends on what kind of NAV you have in the plane. Most of these are not groundbreaking.

  • I use IAS climbs and VS descents to make sure I don't get too slow in a climb. Some pilots have had issues with oscillations in IAS mode and have documented it here on MS. When you push the IAS button it sets the climb to your current IAS. Instead of making a quick change to the target IAS, (say I'm level with an IAS of 140 but want to climb at 120) I wait a couple seconds and then use the dial to change it slowly and I haven't had the oscillation issue. 
  • Before TO I will set it to either my cruising altitude or first assigned altitude.
  • Before TO if I have been assigned a heading after departure I will set it to that, or if nothing assigned I set it to runway heading.
  • Biggest "gotcha" occurred when in GPS mode following a flight plan and ATC either gives you a heading to fly or a xx° turn. Before pressing the HDG button to switch to heading mode, push on the heading knob to set it to your current heading, then switch to HDG mode. If not the second you press HDG it is going to start a turn to whatever you had the bug set to last.
  • This is dependent on your NAV. If you have an approach loaded and you activate the approach it is going to turn you to the first point in the loaded approach. Typically here in SoCal it is always vectors to intercept, so I won't activate the approach in my NAV until I make sure the leg I am intercepting is the active on in my NAV.
  • It may never happen to you, but I have had a couple times I reached for something and my arm bumped the TO/GA button which caused the plane to start a pitch up. The first time I thought "What the heck is it doing?" Which brings me to my last one.
  • This goes for all auto pilots, but if it ever starts doing something unexpected just press the disconnect button, then figure out what it is doing. 
  • If you are set up so that it will fly a coupled approach from your NAV, you need to be below glideslope when you engage APR mode for it to intercept and follow it down. If you are above it is just going to keep flying you right along your merry way without descending.
  • The auto-trim is great, if I am hand flying an approach it makes it simple to make very small corrections to pitch without taking my right hand off the throttle.

Skates, great comments!  I’d like to add a couple thoughts, but these are from a slightly different AP (GFC700), although The functions I mention should be the same…

Im just adding to what you said… When you mention no activating the approach until you have the appropriate leg selected for intercept during vtf : As soon as you started receiving your vectors, the AP should be in hdg mode.  This can happen pretty early in contact with approach.  Once in heading mode, you can “activate the approach or activate vtf” on the GPS while remaining in hdg mode on the AP.  When given the last vector to intercept final and cleared the approach, select the approach mode on the AP.  LOC and GS or GPS and GP should come up in white “standby” on the AP mode line on your G5, but the AP should be still in hdg until it intercepts when it will switch to the white modes and they will be green.  I guess I’m saying make sure everyone knows the difference between approach active on the GPS and approach mode on the AP.  They are separate.

I’m with you on my initial reaction to the AP doing something unexpected, but they have been trying to train that out of pilots (maybe unsuccessfully?). In vfr conditions, disconnecting it is probably fine.  In IFR, the level button is probably a better reaction, and then verify and select lateral and vertical modes as situational awareness allows.

Finally, the AP “mode line” at the top of your G5 or G3X needs to be in your crosscheck.  It will show the green active modes and white standby modes.  You need to make sure you’re getting what you want.  It’s easy to hit Direct on the gps to a point you’re already heading close to, see the hsi center up and move on… still in heading mode and close enough that it’s easy to miss…

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Here’s a picture of a G5 with the AP modes in green and a gps approach selected in standby (top of picture).  The white modes will replace the green and become active as the intercept happens and the appropriate conditions are met.

 

5D8781D2-4A8B-4630-ABC5-6A2742497A76.jpeg

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I'm not sure LVL is a good choice if you suspect an autopilot malfunction since LVL uses the autopilot. It's a great choice if you hand fly yourself into an unusual attitude.

"Activate" for approaches is, in my opinion, a poor choice of words because it implies that you must somehow always activate an approach before you can fly it. If you load an approach with an IAF and the flight plan has legs that get you to the IAF, the navigator will fly to the IAF and commence the procedure without any further action. Activate is just a shortcut for setting Direct To the IAF.

A lot of people use "cleared for the approach" as a cue to select APR on the autopilot. 

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31 minutes ago, PT20J said:

I'm not sure LVL is a good choice if you suspect an autopilot malfunction since LVL uses the autopilot. It's a great choice if you hand fly yourself into an unusual attitude.

"Activate" for approaches is, in my opinion, a poor choice of words because it implies that you must somehow always activate an approach before you can fly it. If you load an approach with an IAF and the flight plan has legs that get you to the IAF, the navigator will fly to the IAF and commence the procedure without any further action. Activate is just a shortcut for setting Direct To the IAF.

A lot of people use "cleared for the approach" as a cue to select APR on the autopilot. 

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I agree if you suspect an AP problem, level isn’t good.  I thought we were more talking of those times when you wondered, “why is it going that way?”  In those cases, as long as you haven’t identified a problem, the AP is most likely faithfully following your error in setting it wrong.  Level gives you a safe mode from which to re-setup the system correctly.  And you won’t end up in an unusual attitude troubleshooting.  Maybe one of the airline guys can chime in on their procedures.  Typically I think they fix the AP settings instead of disconnecting when possible.

Depending on the system there are a few other helpful things the GPS might do when you activate an approach it as well. If set to VTF, you get the FAF with the course line “obs” straight out for your intercept.  On some you also get switched to VLOC on your hsi.  Like you said, you can fly the approach without hitting activate on the gps, but you will need to do some of these things yourself.

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3 hours ago, Ragsf15e said:

Depending on the system there are a few other helpful things the GPS might do when you activate an approach it as well. If set to VTF, you get the FAF with the course line “obs” straight out for your intercept.  On some you also get switched to VLOC on your hsi.  Like you said, you can fly the approach without hitting activate on the gps, but you will need to do some of these things yourself.

I think all the Garmin systems will switch to VLOC based on proximity to the final  approach course, FAF, and nav tuning, whether you activate or not.

Many used to advocate against using VTF because it eliminated the fixes before the FAF which could be problematic if you were cleared to one of those fixes to begin the approach. Garmin seems to have fixed this (at least in the GTNs) by extending the VTF course line and including all fixes on that line. 

Personally, I never had an issue. If a controller cleared me to a fix I didn’t have loaded, I just asked for a different clearance. Never had one quibble. Nowadays when I get an enroute clearance to some fix I wasn’t expecting, my usual response is, “Can you give me a vector until I get that loaded, and please spell it?”

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19 minutes ago, PT20J said:

I think all the Garmin systems will switch to VLOC based on proximity to the final  approach course, FAF, and nav tuning, whether you activate or not.

Many used to advocate against using VTF because it eliminated the fixes before the FAF which could be problematic if you were cleared to one of those fixes to begin the approach. Garmin seems to have fixed this (at least in the GTNs) by extending the VTF course line and including all fixes on that line. 

Personally, I never had an issue. If a controller cleared me to a fix I didn’t have loaded, I just asked for a different clearance. Never had one quibble. Nowadays when I get an enroute clearance to some fix I wasn’t expecting, my usual response is, “Can you give me a vector until I get that loaded, and please spell it?”

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I also use the vtf mode and haven’t run into a problem, however I will load a full approach from a convenient iaf so that i have all the points initially.  Sometimes I’ll get sent to one of those.  Once tge start giving vectors, I’ll “activate VTF” to set up that last portion.

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29 minutes ago, PT20J said:

I think all the Garmin systems will switch to VLOC based on proximity to the final  approach course, FAF, and nav tuning, whether you activate or not.

Many used to advocate against using VTF because it eliminated the fixes before the FAF which could be problematic if you were cleared to one of those fixes to begin the approach. Garmin seems to have fixed this (at least in the GTNs) by extending the VTF course line and including all fixes on that line. 

Personally, I never had an issue. If a controller cleared me to a fix I didn’t have loaded, I just asked for a different clearance. Never had one quibble. Nowadays when I get an enroute clearance to some fix I wasn’t expecting, my usual response is, “Can you give me a vector until I get that loaded, and please spell it?”

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I’m a little curious what you meant about an auto switch to vloc based on proximity, etc.  I agree that will happen if you are established on the approach from an earlier point or leg, but I think the scenario we were talking about is while getting vectors nearing a final intercept.
You can certainly fly an ILS  approach without hitting activate VTF on the gps, but you will have to set the gps point to the faf if you want distance and you’ll have to manually switch your hsi to vloc prior to intercepting final.  Maybe I’m wrong though?  I learn something new everyday…

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3 hours ago, Ragsf15e said:

I’m a little curious what you meant about an auto switch to vloc based on proximity, etc.  I agree that will happen if you are established on the approach from an earlier point or leg, but I think the scenario we were talking about is while getting vectors nearing a final intercept.
You can certainly fly an ILS  approach without hitting activate VTF on the gps, but you will have to set the gps point to the faf if you want distance and you’ll have to manually switch your hsi to vloc prior to intercepting final.  Maybe I’m wrong though?  I learn something new everyday…

Assuming we are talking about the same thing, automatic VLOC switching is a setup option. Here is the description for the GNS 430W/530W:

437961211_Screenshot2022-11-10at8_21_39PM.png.bf15332362cd561c7506eb42af5cdc0d.png
 

And here’s the description for the GTN 650/750Xi:

625861165_Screenshot2022-11-10at8_22_41PM.png.8fb0f99e271ee71fdfb3cf30d50713ec.png

 

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32 minutes ago, PT20J said:

Assuming we are talking about the same thing, automatic VLOC switching is a setup option. Here is the description for the GNS 430W/530W:

437961211_Screenshot2022-11-10at8_21_39PM.png.bf15332362cd561c7506eb42af5cdc0d.png
 

And here’s the description for the GTN 650/750Xi:

625861165_Screenshot2022-11-10at8_22_41PM.png.8fb0f99e271ee71fdfb3cf30d50713ec.png

 

I believe you must “activate the approach” first for auto switching to occur.  Here’s the paragraph just previous to your 430w page…

61A5D447-E276-42E3-BE88-E40A762BE9BC.jpeg.5d6ecee17e98f0d633b9ad1ef152c805.jpeg

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8 hours ago, PT20J said:

"Activate" for approaches is, in my opinion, a poor choice of words because it implies that you must somehow always activate an approach before you can fly it.

100% concur.  It's especially confusing because it implies the GNS/GTN navigators have some "mode" or "state" they go into, where the approach is "active".  That's not the case.  An instrument approach - which is just a flight plan with multiple legs - cannot be "active" (or "inactive") in the navigator.  Only a leg of a flight plan can be active, and only one leg can be active at any particular time.

I teach students that "activate approach" is simply shorthand for "Create a leg from present position, direct to the initial approach fix of the approach that is currently loaded, and make that the active leg in the flight plan" (VTF is a special case of this which substitutes a point out at infinity for present position).  Since that's a mouthful, and won't fit on a screen, Garmin invented a shorthand phrase for it - "activate approach".  I get that, but would have been much less confusing if they'd chosen "Goto IAF" for full approach and "Goto VTF" for VTF.

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12 hours ago, Ragsf15e said:

I believe you must “activate the approach” first for auto switching to occur.  Here’s the paragraph just previous to your 430w page…

61A5D447-E276-42E3-BE88-E40A762BE9BC.jpeg.5d6ecee17e98f0d633b9ad1ef152c805.jpeg

I’m pretty sure that the GNS considers an approach “Activated” whenever the IAF is the active waypoint, or a leg of the approach is the active leg. Maybe @donkaye or @kortopates can clarify.

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1 hour ago, PT20J said:

I’m pretty sure that the GNS considers an approach “Activated” whenever the IAF is the active waypoint, or a leg of the approach is the active leg. Maybe @donkaye or @kortopates can clarify.

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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  

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from the AIM: 

https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap5_section_4.html

Selection of “Vectors-to-Final” or “Vectors” option for an instrument approach may prevent approach fixes located outside of the FAF from being loaded into an RNAV system. Therefore, the selection of these options is discouraged due to increased workload for pilots to reprogram the navigation system.

 

https://bruceair.wordpress.com/2010/11/24/avoiding-the-vectors-to-final-scramble/

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14 minutes ago, rbp said:

from the AIM: 

https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap5_section_4.html

Selection of “Vectors-to-Final” or “Vectors” option for an instrument approach may prevent approach fixes located outside of the FAF from being loaded into an RNAV system. Therefore, the selection of these options is discouraged due to increased workload for pilots to reprogram the navigation system.

 

https://bruceair.wordpress.com/2010/11/24/avoiding-the-vectors-to-final-scramble/

The guidance from the AIM makes no distinction from PA vs NPA. On any NPA, VTF should always be discouraged because step down fixes are critical. But the PA is a safe exception that except for a very rate gotcha is safe to use VTF; especially with the GTNs that don't omit waypoints on the final approach outside of the FAF.

I used to teach no VTF with out exception like the AIM suggest, but learned there is seldom any reason not to use VTF for a PA.

So as an example, when your being vectored outside of the FAF, on a PA and the controller says something like" 2 miles from XXXX (FAF), Maintain 3000 until established" the proper thing to do is to maintain 3000 not only till i) established and ii) till the GS comes down to you and then follow it to the MAWP.

The only real gotcha is possible maximum altitudes on outside of FAF step downs on very long finals that are very uncommon. Some get concerned though when the controller is vectoring you to final and says direct to one of the IF fixed outside of the final. But in this case, just intercepting final as you have it already set up works just as well. Although with the GTN, you still have the waypoint in the flight plan and could hit direct to it, but when that happens to me despite the capability to do I won't bother as there isn't a significant difference. 

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BTW, I don't advocate relying on setting the option to automatically switch to LOC from GPS with the Garmin Navigators for two reasons:

1) the switch doesn't occur until you're final close to intercepting final. But I want to start monitoring where I am on the GS as soon as I am on what I would refer to as the base leg vector for the approach; essentially perpendicular to final. At this stage its very helpful to know if I still have time to capture the GS or if its going to be a race to get established and then descend.

2) Because the change in Mode (Loc vs GPS) causes the GNC-500 AP to disconnect, I want to be the one to switch so I can immediately re-enable the AP in approach mode - rather than be surprised by it!

 

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I got caught once off guard getting vectors from Tracon, selecting VTF, and then getting cleared for the approach via a fix, which had been ceremoniously deleted from the flight plan.

yes, it was my fault for selecting vectors to final before the clearancE, but I vowed then and there never to again use vectors to final 

 

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I see the old saw of "Don't use VTF" has come up again, and that it's now been codified in the AIM (of which I was unaware, thanks for the link).

I don't disagree with the guidance itself, particularly with the older GNS navigators and their etch-a-sketch user interface.  The problem I have with the way this guidance is usually phrased, though - including what's now codified in the AIM - is the implication that reprogramming your navigator based on a final set of intercept instructions from ATC, late in the approach game, is somehow "unreasonable" and must be avoided.  That it's too high of a workload during that phase of flight, and that you're too likely to screw up if you even try it.

Reducing workload is always a good idea, but it's my position that you're always subject to last-minute changes to your approach plan from ATC, and that being nimble enough with your navigator to handle them is a required skill for the proficient IFR pilot.  If you're proficient in that way, the "Don't use VTF" guidance becomes moot.  If you're not... well, you can avoid the problem where VTF omits points you may be cleared to; but there are similar problems unrelated to VTF that you're not going to handle well.

Here's an example: where I fly, it's not uncommon to be told to "expect the GPS 29 approach to KLMO", which you can dutifully load in the recommended manner, selecting either WOLTS or FIPPS as the IAF depending on which direction you're coming from.  Roughly half the time, the next ATC instruction - late in the game - is "cleared direct FIMUR, cleared for the approach".  FIMUR is an IF, and ATC is permitted to clear you direct to an IF rather than an IAF if the resultant turn to the final approach course is less than 90 degrees.  This is becoming more common, as T-shaped and V-shaped GPS approaches see more and more use.  To comply with such a clearance, you must push a non-trivial sequence of buttons - again, late in the approach game - even when you "did the right thing" of loading the full approach.

Here's another example: say you're approaching KBAZ (New Braunfels, TX) with winds from the northwest.  There are equally good approaches to equally good runways 31 and 35.  This is an uncontrolled airport, there is no tower/ATIS to tell you which approach(es) are "in use".  As the wind moves around and various CTAF reports roll in, the proficient pilot has no issue switching from one of these approaches to another, relatively close to the airport.  The un-proficient/less proficient pilot will be reluctant to change the approach they loaded early in the game, even if there is good reason to do so.  Sticking to the plan in this manner avoids getting wrapped around the axle of re-programming the navigator, but introduces other risks.

For these sorts of reasons, late-in-the-game reprogramming is part of what I teach as a CFII, during the final stage of instrument training and in IPCs.  If I'm simulating ATC, I don't care what you load in the navigator (including VTF).  But whatever you load, I'm going to give you a late change and see how you handle it.  If you load VTF, I'm going to clear you to an approach fix that's no longer in the flight plan.  If you load a full approach with an IAF, I'm going to clear you to a different IAF or IF.  If I can't reasonably do either of those, I'll just say that "due to wind changes, need to clear you to a different approach".  If the pilot has trouble with any of these things, I'll suggest additional training with an iPad trainer or similar, to become more familiar with the navigator.  The analogy I use is that of a typist.  Sure, you can get by with hunt-and-peck, but professionals know how to touch type.

Having said all that, the main reason I give students late-in-the-game navigator programming changes is, I want them to understand the ultimate tool in the tool bag: "Unable, I'll need vectors until I can reprogram my navigator".  As with so many things in aviation, I want my students to have plans for what they're going to do if they get into a scenario they hoped to avoid, rather than thinking they can somehow guarantee the scenario won't happen in the first place.  In my mind, saying, "I don't allow myself to get into a situation where I have to reprogram the approach", is like saying, "I don't allow myself to get into a situation where I have to land in a strong crosswind".  Of course you can make go/no-go decisions that minimize the risk of that, but you can't guarantee the weather at your destination (not even if it's the same as your departure); and we still encourage training for crosswind landings.  So it goes with navigator programming, in my opinion.

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6 hours ago, PT20J said:

I’m pretty sure that the GNS considers an approach “Activated” whenever the IAF is the active waypoint, or a leg of the approach is the active leg. Maybe @donkaye or @kortopates can clarify.

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Yes, I’d agree with that.  You do have to “activate” it somehow if you want the automated switching to vloc, but yes, there are different ways to “activate”.

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