I'm using the TDS Garmin 750, and the LNAV component works fine - although it took me a while to work out I needed to use it in HDG mode, not Nav mode, but I can't get it to follow the glide path down.

I'm in GPS mode on the indicator below the RMI and also indicating GPS mode on the Garmin, the GPS APR mode on the indicator below the RMI is showing ARM, if I press the Approach mode on the autopilot is shows armed, and GP is shown in the autopilot annunciator on the panel, but the aircraft never descends on the glide path.

VNAV is shown in green on the bottom left of the PFD, but the glidepath red flags don't clear. It must be something obvious I'm doing wrong - but I'm not able to work out what it is?

Any ideas?

Thanks

Eugene

There is no VNAV support yet in the TDS GTN Xi.  You will get vertical guidance (glide path showing on the HSI) on an RNAV(GPS) instrument approach with vertical minimums

What exact approach is it?  I can check on my end.

It was the Liverpool EGGP RNP 27, just a short hop from Manchester EGCC, and lined up for the approach. 

Thanks for letting me know, didn't realise there was no vnav support for it. Don't think I've seen any glide path information, but will look more carefully next time. The glide path red flags are showing on the PFD and HSI. 

Eugene 

11 minutes ago, Overload said:

It was the Liverpool EGGP RNP 27, just a short hop from Manchester EGCC, and lined up for the approach. 

Thanks for letting me know, didn't realise there was no vnav support for it. Don't think I've seen any glide path information, but will look more carefully next time. The glide path red flags are showing on the PFD and HSI. 

Eugene 

Let me fly it right now and see what's up

Everything works here:

eggprnav27 by Ryan Butterworth, on Flickr

Edited October 22, 20223 yr by ryanbatc

Hmmm, interesting, I was using the autopilot, will try it in manual mode. Can you get the autopilot to intercept the glide path? 

Just now, Overload said:

Hmmm, interesting, I was using the autopilot, will try it in manual mode. Can you get the autopilot to intercept the glide path? 

I haven't specifically tried that.  But if you aren't even seeing the green triangle Glide path then there is an issue.

1 minute ago, Overload said:

Hmmm, interesting, I was using the autopilot, will try it in manual mode. Can you get the autopilot to intercept the glide path? 

I didn't fly your particular approach, but another RNAV RNP I did use autopilot in approach mode without any issues

15 minutes ago, Overload said:

Hmmm, interesting, I was using the autopilot, will try it in manual mode. Can you get the autopilot to intercept the glide path? 

Ok I intercepted just fine using autopilot.  Used APPR mode and the lights above the ADI look just like SD_Flyer's and the AP lights are shown here

Can you post a pic of your panel with the approach loaded and also the AP panel like I have below?

eggprnav27AP by Ryan Butterworth, on Flickr

Edited October 22, 20223 yr by ryanbatc

Thanks guys, great information, sim is shut down now, 2300 uk time, but will take some screen shots tomorrow, pretty sure I don't get a vnav armed indication on the autopilot, but will post a pic in the morning.

Thanks

Eugene 

So airborne from EGCC, 2000ft, RNP 27 EGGP loaded and activated, 8.4 miles to the final Approach fix UVERI,

My autopilot settings are different, in addition to the settings shown in Ryan's pic, I've also got HDG and ALT showing. The red Glide Path flags are showing and never clear. Once I reach UVERI the aircraft establishes on the final approach track, but still maintains 2000ft. Green LN and VNAV indications are showing on the HSI.

 

I found out by accident that the only way I can get it to follow LNAV is by using it in HDG mode. I don't turn the HDG bug myself, the autopilot automatically turns it to follow the LNAV tracks.

If I press the autopilot NAV button, which is the normal way to engage LNAV in GPS mode, the autopliot shows NAV ARM but it never captures the track. 

The autopilot annunciator is showing NAV, but the course is 267 degrees, it never turns towards it, unless I press  HDG mode.

 

I think the reason is something to do with the NAV/HDG issue, but still can't work it out !

Thanks for your help,

Eugene

 

 

 

 

21 minutes ago, Overload said:

So airborne from EGCC, 2000ft, RNP 27 EGGP loaded and activated, 8.4 miles to the final Approach fix UVERI,

My autopilot settings are different, in addition to the settings shown in Ryan's pic, I've also got HDG and ALT showing. The red Glide Path flags are showing and never clear. Once I reach UVERI the aircraft establishes on the final approach track, but still maintains 2000ft. Green LN and VNAV indications are showing on the HSI.

 

I found out by accident that the only way I can get it to follow LNAV is by using it in HDG mode. I don't turn the HDG bug myself, the autopilot automatically turns it to follow the LNAV tracks.

If I press the autopilot NAV button, which is the normal way to engage LNAV in GPS mode, the autopliot shows NAV ARM but it never captures the track. 

The autopilot annunciator is showing NAV, but the course is 267 degrees, it never turns towards it, unless I press  HDG mode.

 

I think the reason is something to do with the NAV/HDG issue, but still can't work it out !

Thanks for your help,

Eugene

 

 

 

 

Did you activate your approach in GPS? PROC->APPROACH->RNAV->ACTIVATE VECTOR TO FINAL ?

35 minutes ago, Overload said:

I think the reason is something to do with the NAV/HDG issue, but still can't work it out !

I'll fly the approach and test. I've had no issues with RNP approaches in this aircraft. 

35 minutes ago, Overload said:

My autopilot settings are different, in addition to the settings shown in Ryan's pic, I've also got HDG and ALT showing. The red Glide Path flags are showing and never clear. Once I reach UVERI the aircraft establishes on the final approach track, but still maintains 2000ft. Green LN and VNAV indications are showing on the HSI.

Would make more sense to be in NAV mode with GPS active on the TDS? Then as @sd_flyer mentions make sure you've activated the approach in the TDS (menu=>PROC=>activate approach). Could also be a good idea to be at 2000' at INVEB as per the approach plate. That gives you 3.5nm to slow down before starting the glidepath at UVERI. 

Edited October 23, 20223 yr by Cpt_Piett

1 hour ago, Overload said:

I think the reason is something to do with the NAV/HDG issue, but still can't work it out !

Thanks for your help,

Eugene

Decided to make a video, hopefully the quality is good enough (the cockpit is very dark, sorry) and that it might be of some help. Make sure you have the latest version of the TDS as they've updated the autopilot logic in recent updates. 

EDIT: Got a bit distracted there so speed got a bit low on the approach. No excuses 🙂

 

Edited October 23, 20223 yr by Cpt_Piett

9 minutes ago, Cpt_Piett said:

Decided to make a video, hopefully the quality is good enough and that it might be of some help. Make sure you have the latest version of the TDS as they've updated the autopilot logic in recent updates. 

 

This is good advice. 

@Overload

Also check the interface (right click the app in the Windows system tray), make sure autopilot is linked and settings are correct.

tdssettings by Ryan Butterworth, on Flickr

Edited October 23, 20223 yr by ryanbatc

19 hours ago, ryanbatc said:

Let me fly it right now and see what's up

Everything works here:

eggprnav27 by Ryan Butterworth, on Flickr

Looking at the airspeed indicator marking for max flap extension speed it appears to show on the high side of 220 knots. i think it should be 202 knots.