TBM 850 - ILS capture problem

[Area 21]

I'm having a problem capturing the ILS.

I am doing an ILS approach without the PMS50-GTN750 GPS, I am flying in HDG + HSI LOC 1 heading on the ILS, APPR armed, ALT FAP. When I arrive on the axis via a 45° route, the TBM 850 captures the LOC then the G/S without problem.

I am flying in GPS mode with Airport+waypointS+Airport flight plan with the PMS50-GTN750 GPS.
When I arrive on the last leg I switch to HDG to join the IF of the ILS approach (I do not use the approach function of the GTN 750). To do this I leave GPS mode for LOC 1 mode, I enter the ILS frequency on the GTN 750 and engage it (green frequency), I align the HSI LOC 1 heading on the ILS, APPR armed, ALT = FAP. The PFD displays the LOC and G/S well but when I arrive on the axis via a 45° route the TBM 850 continues in the direction of the HDG.

What am I doing wrong, please?

[sd_flyer 6,272]

Did you hit APR button on autopilot?

[Area 21]

Yes, I mention it in my message "....I align the HSI LOC 1 heading on the ILS, APPR armed, ALT = FAP..."

I feel like using the PMS50-GTN750 for airport to airport navigation prevents me from ending up with a traditional ILS approach.

[sd_flyer 6,272]

3 minutes ago, Area said:

Yes, I mention it in my message "....I align the HSI LOC 1 heading on the ILS, APPR armed, ALT = FAP..."

I feel like using the PMS50-GTN750 for airport to airport navigation prevents me from ending up with a traditional ILS approach.

Did you switch GPS to VLOC?

[Area 21]

Yes, I mention it in my message "...To do this I leave GPS mode for LOC 1 mode, I enter the ILS frequency on the GTN 750 and engage it (green frequency), I align the HSI LOC 1 heading on the ILS, APPR armed, ALT = FAP. The PFD displays the LOC and G/S well but when I arrive on the axis via a 45° route the TBM 850 continues in the direction of the HDG." by pressing [CDI]

after pressing [CDI] the GPS (purple) changes from GPS to VLOC (green) and the HSI changes GPS to LOC 1.

[MattNischan 3,955]

In order to do this, you must also arm NAV mode as well. I don't believe pressing APPR automatically arms NAV for capture, but only G/S in this case you are describing.

[sd_flyer 6,272]

40 minutes ago, Area said:

Yes, I mention it in my message "...To do this I leave GPS mode for LOC 1 mode, I enter the ILS frequency on the GTN 750 and engage it (green frequency), I align the HSI LOC 1 heading on the ILS, APPR armed, ALT = FAP. The PFD displays the LOC and G/S well but when I arrive on the axis via a 45° route the TBM 850 continues in the direction of the HDG." by pressing [CDI]

after pressing [CDI] the GPS (purple) changes from GPS to VLOC (green) and the HSI changes GPS to LOC 1.

Given that you intercept localizer in HDG. If you activated approach and arm APR mod prior intercept autopilot should establish on localizer itself 

[Area 21]

I completely agree with you.

I have the impression that using the PMS50-GTN750 for airport-to-airport navigation generates a malfunction if we switch to a traditional ILS approach.

If anyone has encountered this problem, I would be happy to read about it.

[Flyfaster_MTN002 412]

Fly the RNAV. Problem solved 🙂

[Bert Pieke 7,628]

7 hours ago, MattNischan said:

In order to do this, you must also arm NAV mode as well. I don't believe pressing APPR automatically arms NAV for capture, but only G/S in this case you are describing.

That is actually contrary to established procedures:   NAV to get aligned with the runway (final), set heading bug, switch to HDG mode, switch GPS to VLOC mode with correct ILS frequency dialed in, check for HSI needles active, switch to APR.

APR should capture both the localizer and the glideslope.

[Bert Pieke 7,628]

9 hours ago, Area said:

To do this I leave GPS mode for LOC 1 mode, I enter the ILS frequency on the GTN 750 and engage it (green frequency)

The moment you push the CDI key on the GPS, to switch from GPS mode to VLOC mode, the GPS is out of the picture.  You are now flying without a GPS, just with a NAV radio.  Anything you can do without a GPS in the panel, you can do with the GPS in VLOC mode.

[rick celik 1,272]

Download the extra package for the TBM website for the GTN, this solved my navigation problems with the TBM. At work currently but maybe someone can point you to direct link.

fyi the package is located on the PMS website. 

Edited November 30, 2023 by Ridvan Celik

[ark 1,306]

10 hours ago, MattNischan said:

In order to do this, you must also arm NAV mode as well. I don't believe pressing APPR automatically arms NAV for capture, but only G/S in this case you are describing.

The Bendix/King KFC 325 Autopilot Pilot's Guide says this when discussing using the Approach mode to intercept and capture the localizer:

Any horizontal tracking mode may be employed during Approach Arm phases, but will cancel automatically upon initiation of Approach Capture and Track.

Likewise, the Guide also says Glideslope capture deactivates any other vertical mode.

So typical autopilot operation in my experience.

Al

Edited November 30, 2023 by ark

[Area 21]

Many thanks to everyone for your opinions.

I am going to do a flight with GPS navigation then traditional ILS approach first with HDG then as you recommend NAV mode and finally APPR.
Thanks also @Ridvan Celik for the info on the GTN750 module for the TBM850, I just downloaded it.

[rick celik 1,272]

1 hour ago, Area said:

Many thanks to everyone for your opinions.

I am going to do a flight with GPS navigation then traditional ILS approach first with HDG then as you recommend NAV mode and finally APPR.
Thanks also @Ridvan Celik for the info on the GTN750 module for the TBM850, I just downloaded it.

Sure no problem, your nav equipment should work with that package installed. I wasn’t even aware of that extra package until two weeks ago, couldn’t do ils or rnav approaches at all, until I installed it.
 

Let us know how you go 🤙🏼