Noob IFR Question - NAV to APR

[Virtual-Chris 682]

Hi, I'm using G1000 in the 208B Grand Caravan to do low altitude IFR flights (with ILS Approach).

At what point are you supposed to switch the AP from NAV mode to APR mode?

Also, as I got close to the runway, I switched off AP to manually land... but the nose popped up and was all over the place... I'm guessing as the AP unwound all the trim or something?  Is this normal?

Thanks!

Edited September 30, 2020 by Virtual-Chris

[HPG 403]

I usually turn approach mode on when both my horizontal and vertical magentas are centered. It's my understand that this should happen automatically however, but it has never worked for me.

This was in the 1.8.3 patch notes, my understanding could be wrong though.

Quote

• G1000 : automatically switches from NAV to LOC when needed.

 

[Highmike 68]

Anytime your glideslope indicator is green or magenta (whichever it may be), and you're below the glideslope, and your localizer is reasonably centred, i.e. you're lined up on the runway, anytime these three conditions are met you can hit the APP button. I tend to do it sooner rather than later, but that could be just me.

You'll want to do your own experiments with variations on this and you'll get the drift of how and when to hit it, but keep in mind the programming of the auto approach function is still a bit iffy in this sim compared with other sims like FSX or P3D.

[Flyfaster_MTN002 412]

1 hour ago, Virtual-Chris said:

Hi, I'm using G1000 in the 208B Grand Caravan to do low altitude IFR flights (with ILS Approach).

At what point are you supposed to switch the AP from NAV mode to APR mode?

Also, as I got close to the runway, I switched off AP to manually land... but the nose popped up and was all over the place... I'm guessing as the AP unwound all the trim or something?  Is this normal?

Thanks!

To make life easier be sure to put your final waypoint (GPS FIX) in the FP as the IAF for the approach and then just engage APPR upon arrival at said FIX

[Virtual-Chris 682]

52 minutes ago, Flyfaster said:

To make life easier be sure to put your final waypoint (GPS FIX) in the FP as the IAF for the approach and then just engage APPR upon arrival at said FIX

I'm just using the built-in flight planner for now. And of course it has several waypoints from the start to the end. I looked at the approach plates and can tell at which point I should be entering the approach and which one I should be intercepting the glide slope.
 

Should I be engaging Approach mode at the first ILS waypoint or where I Intercept the glide slope?

 

I'm guessing from what others are saying I should enable it once I Intercept the glide slope. 

Edited October 1, 2020 by Virtual-Chris

[JimBrown 596]

I'm not a real world pilot, so take this with a grain of salt... I usually hit the LOC button when the bottom horizontal indicator is almost at the center. I then hit APPR when the vertical indicator is about half way towards the center. From what I've read, you really want to hit APPR before the vertical indicator hits the center but after it has started moving down towards the center. It is not necessary to hit the LOC button first, one could go straight to the APPR button if one wished. But if I'm approaching the ILS low enough, I may be on the localizer well before the glide slope.

Just the way I do it. Doesn't mean its right. 😉

...jim

[Ajb376 59]

As a real world pilot, I'll chime in, 5 degree deflection - IE the CDI (green line - ILS or LOC) or Nav (magenta line - RNAV) is deflected and directly over one of the closest dots on the HSI.

ILS - Heading mode, vectored to final by approach, Approach in standby and it should flip when you activate approach to final. 

RNAV - NAV (GPS) mode and approach in standby.

Explain It Like I'm 5 version: the little green or magenta line thingy is over the two closest white transparent dots on the compass in the PFD on the G1000.

 

[Flyfaster_MTN002 412]

50 minutes ago, Virtual-Chris said:

I'm just using the built-in flight planner for now. And of course it has several waypoints from the start to the end. I looked at the approach plates and can tell at which point I should be entering the approach and which one I should be intercepting the glide slope.
 

Should I be engaging Approach mode at the first ILS waypoint or where I Intercept the glide slope?

 

I'm guessing from what others are saying I should enable it once I Intercept the glide slope. 

In a perfect world yes assuming you are on and/or below the glide path, but with the bugs this thing has who knows at this point. Try leaving the AP in NAV mode the way I described above, and see if it auto-sequences to APPR mode when it hits the IAF.

[Moria15 950]

3 hours ago, Virtual-Chris said:

I'm just using the built-in flight planner for now. And of course it has several waypoints from the start to the end. I looked at the approach plates and can tell at which point I should be entering the approach and which one I should be intercepting the glide slope.
 

Should I be engaging Approach mode at the first ILS waypoint or where I Intercept the glide slope?

 

I'm guessing from what others are saying I should enable it once I Intercept the glide slope. 

There were some good changes to this in 1.9.3 that majorly improved the auto switching from NAV when approaching.

If you are using the flightplanning tool from the world menu options to arrive at an ILS, you will see that the final stages are a long straight line out of the arrival runway...   when you are established this line you should hit APPR and then it should also auto switch from Nav when in range of the beacon.   (If your purple line switches to green before you are fully established on that approach line.. hit APPR then instead)

The only issue you have now is that sometimes, ATC vectores you in just a little too high to intercept the glide slope even if all the above was done correctly...

Work on this basis..  before that final turn, you will know (from ATC) how far away from the airport you are.. usually around 6/7 miles...   If ATC have you at more than 1800 ft above runway level at that point, you are likely too high for the current sim settings to always correctly intercept the glide slope when it registers.

Also remember to keep power up during approach.. I have noticed that if your power/speed is too low, then to keep you high when you do have the G/S, the sim cannot change the thrust for you on any prop aircraft, so it changes pitch to keep nose up which either drives you into a stall, or if you drop the AP, you jump into a totally nose up position...    watch the trim control as you are descending and if trim starts to nose up.. then add power 🙂

Hope this helps..

Graham

Edited October 1, 2020 by Moria15

[Virtual-Chris 682]

58 minutes ago, Moria15 said:

There were some good changes to this in 1.9.3 that majorly improved the auto switching from NAV when approaching.

If you are using the flightplanning tool from the world menu options to arrive at an ILS, you will see that the final stages are a long straight line out of the arrival runway...   when you are established this line you should hit APPR and then it should also auto switch from Nav when in range of the beacon.   (If your purple line switches to green before you are fully established on that approach line.. hit APPR then instead)

The only issue you have now is that sometimes, ATC vectores you in just a little too high to intercept the glide slope even if all the above was done correctly...

Work on this basis..  before that final turn, you will know (from ATC) how far away from the airport you are.. usually around 6/7 miles...   If ATC have you at more than 1800 ft above runway level at that point, you are likely too high for the current sim settings to always correctly intercept the glide slope when it registers.

Also remember to keep power up during approach.. I have noticed that if your power/speed is too low, then to keep you high when you do have the G/S, the sim cannot change the thrust for you on any prop aircraft, so it changes pitch to keep nose up which either drives you into a stall, or if you drop the AP, you jump into a totally nose up position...    watch the trim control as you are descending and if trim starts to nose up.. then add power 🙂

Hope this helps..

Graham

Thanks. That makes a lot of sense. I noticed the Nav switch to the beacon around the time I switched modes, but not sure if it’s because I switched modes or it was just coincidence.

From these forums and my own experience, I’ve learned to ignore the ATC as I get closer to the airport (They had me heading into a mountain last time) and instead set myself up at an altitude to intercept the glide slope as indicated on the plate. 

Good point about the throttle... I was definitely low on the throttle on the final approach, which probably caused the lurch when I disabled AP. That makes perfect sense. It will be another learning curve to get the throttle right for glide slope landings. I’m very guilty of coming in hot and high when flying VFR so dropping the throttle with full flaps on a steep approach is my MO. This nice gentle glide slope approach is going to require a bit more finesse 😉

 

[Moria15 950]

10 minutes ago, Virtual-Chris said:

Thanks. That makes a lot of sense. I noticed the Nav switch to the beacon around the time I switched modes, but not sure if it’s because I switched modes or it was just coincidence.

From these forums and my own experience, I’ve learned to ignore the ATC as I get closer to the airport (They had me heading into a mountain last time) and instead set myself up at an altitude to intercept the glide slope as indicated on the plate. 

Good point about the throttle... I was definitely low on the throttle on the final approach, which probably caused the lurch when I disabled AP. That makes perfect sense. It will be another learning curve to get the throttle right for glide slope landings. I’m very guilty of coming in hot and high when flying VFR so dropping the throttle with full flaps on a steep approach is my MO. This nice gentle glide slope approach is going to require a bit more finesse 😉

 

Yeah 🙂  keep the speed just inside the white line,  so for example  cessna 172, don't drop below 75 with one stage of flaps and you should be fine...  kill the speed right on the flare and you should be fine without the A/P trying to force trim 🙂

Graham