Jump to content

STEC 55x ILS capture


Recommended Posts

 

On 12/2/2017 at 2:40 PM, PaulM said:

I flew a few approaches today.  The 1st RNAV did not switch to APR mode, but I may have not been on a published segment to the FAF.

The second RNAV approach (LPV) enabled APR+GS mode as soon as I hit the NAV button from HDG.

Checked an ILS and it also immediately went into APR+GS when hitting the NAV button.
So, the APR button is only required for VOR approaches and perhaps GPS non Localizer precision.  

I also adjusted the roll centering on the way home. 

I flew a whole bunch of approaches this past Monday for 6 in 6 + automation testing & the new software rev.  S55X behavior only.. 

All approaches were flown with GPSS as full procedures until the leg before the FAF.. 

I found some interesting things when deleting the "hold/procedure turn" at the beginning of an approach, it seemed to create a  discontinuity. 

the AP will not go into APR or GS capture mode from an enroute GPSS nav.   you have to push a button.   (hence why my 1st RNAV didn't switch in December, I joined the RNAV on the base leg) 

Flew a RNAV LNAV+V... outside the FAF hit APR to get approach mode + GS couple for the +V indications.  that +V goes all the way to the ground, it doesn't stop at  the MDA. 

Flew a ILS with full GPSS procedure turn.   MGJ ILS03.. the procedure turn is outside of NISSN so it was GPSS all the way to NISSN and then auto-switched to LOC. (but we were already centered by the step down segment)   The STEC remained in NAV mode and needed a button  (APR) to engage APR/GS.  (It did not go to ROL mode)

Flew another RNAV LP+V... again needed to push APR to engage APR/GS

So,   the conclusion is that the STEC needs to have a button pushed on the segment outside of the FAF.  APR always works.  This is normal with Vectors to final, but is an additional press for GPSS full approaches. 

I will do some more testing to see if just pressing "NAV" works just outside the FAF. 

I will also test the procedure turn to LOC G1000 auto-switch when the turn is from the FAF, which should switch to LOC before we are established on the inbound course. 

 

Link to comment
Share on other sites

 
I flew a whole bunch of approaches this past Monday for 6 in 6 + automation testing & the new software rev.  S55X behavior only.. 
All approaches were flown with GPSS as full procedures until the leg before the FAF.. 
I found some interesting things when deleting the "hold/procedure turn" at the beginning of an approach, it seemed to create a  discontinuity. 
the AP will not go into APR or GS capture mode from an enroute GPSS nav.   you have to push a button.   (hence why my 1st RNAV didn't switch in December, I joined the RNAV on the base leg) 
Flew a RNAV LNAV+V... outside the FAF hit APR to get approach mode + GS couple for the +V indications.  that +V goes all the way to the ground, it doesn't stop at  the MDA. 
Flew a ILS with full GPSS procedure turn.   MGJ ILS03.. the procedure turn is outside of NISSN so it was GPSS all the way to NISSN and then auto-switched to LOC. (but we were already centered by the step down segment)   The STEC remained in NAV mode and needed a button  (APR) to engage APR/GS.  (It did not go to ROL mode)
Flew another RNAV LP+V... again needed to push APR to engage APR/GS
So,   the conclusion is that the STEC needs to have a button pushed on the segment outside of the FAF.  APR always works.  This is normal with Vectors to final, but is an additional press for GPSS full approaches. 
I will do some more testing to see if just pressing "NAV" works just outside the FAF. 
I will also test the procedure turn to LOC G1000 auto-switch when the turn is from the FAF, which should switch to LOC before we are established on the inbound course. 
 


My 60-2 is setup a little differently but what you described about the button pushing sounds correct. If I am flying a precision approach whether it is a GPS or ILS, I need to hit the Nav button to get it into approach mode.

For me, I fly using the STEC in HDG mode and the Aspen in GPSS mode. Before the FAF and after any procedure turn, I hit the NAV button to put the unit in approach mode. The GTN will be showing the LPV or have switched to VLOC.

Have you flown it using vectors to final and see what you need to do?


Sent from my iPad using Tapatalk Pro
Link to comment
Share on other sites

1 hour ago, Marauder said:

 


My 60-2 is setup a little differently but what you described about the button pushing sounds correct. If I am flying a precision approach whether it is a GPS or ILS, I need to hit the Nav button to get it into approach mode.

For me, I fly using the STEC in HDG mode and the Aspen in GPSS mode. Before the FAF and after any procedure turn, I hit the NAV button to put the unit in approach mode. The GTN will be showing the LPV or have switched to VLOC.

Have you flown it using vectors to final and see what you need to do?


Sent from my iPad using Tapatalk Pro

 

Chris, I think you have an APR mode as well as NAV mode on the 60-2? I do on a STEC 50 and I switch from HDG to APR for more sensitive tracking once I'm lined up on the final path, GPS or ILS. 

Link to comment
Share on other sites

Chris, I think you have an APR mode as well as NAV mode on the 60-2? I do on a STEC 50 and I switch from HDG to APR for more sensitive tracking once I'm lined up on the final path, GPS or ILS. 


Nope. One button called “Nav”. If I am flying a VOR signal, like on an airway, activating the Nav button will just track the signal.

If I’m on an approach, hitting NAV on the approach to the FAF activates the APR mode.

efa302e51b5d507b4b14c209f6de7bf5.jpg


Sent from my iPhone using Tapatalk Pro
  • Like 1
Link to comment
Share on other sites

25 minutes ago, Marauder said:

 


Nope. One button called “Nav”. If I am flying a VOR signal, like on an airway, activating the Nav button will just track the signal.

If I’m on an approach, hitting NAV on the approach to the FAF activates the APR mode.




Sent from my iPhone using Tapatalk Pro

 

You have a APR light so I suppose your 60-2 goes into the more sensitive mode automatically where I have to do it manually on the 50.

Link to comment
Share on other sites

17 hours ago, Marauder said:

For me, I fly using the STEC in HDG mode and the Aspen in GPSS mode. Before the FAF and after any procedure turn, I hit the NAV button to put the unit in approach mode. The GTN will be showing the LPV or have switched to VLOC.

Have you flown it using vectors to final and see what you need to do?

This thread was started on S55X specifics.. and then G1000 behavior w/S55X was added. 

the 55x has internal GPSS steering, so we fly that in NAV-NAV mode (two pushes of the nav button).  With a GPS we will be in nav mode for the feeder, through the procedure turn and keep in NAV mode towards the FAF. 

Questions of A/P behavior have evolved since approach operations with a GPS/NAV unit are done differently from the VOR/LOC era of flying when these A/P's were designed.     You used to have to switch between HDG & NAV multiple times in a regular approach either vectors or full procedure.   

We also see generational changes in A/P's.. You used to have to hit APR (King, century, early Stec) to get the APR mode + GS capture.   Stec has changed to using NAV with the precision approach indicator from the NAV unit to go directly into APR mode.. the 55X still includes a separate APR button,.. the S60 doesn't.  

What I am seeing with RNAV and ILS approaches is that vectors to final (or any other process) needs the button (NAV or APR) to be hit on the segment right before the FAF.   Normally with VTF you are vectored to the segment before the FAF, LOC or LP is active and the AP will go right to APR mode. 

If for whatever reason you are vectored to a segment before the FAF for an RNAV or ILS and the nav radio isn't in the LOC/LP mode yet, you are going to have to push the button again when on the FAF segment. 

GPSS in your system is VTF as far as the autopilot is concerned, so your normal process is GPSS/VTF until the NAV indicates  it is in precision mode.      GPSS in the 55X is an extended NAV mode..   What I see as a universal rule is to push the button (NAV/APR) on the segment to the FAF and you will always get the desired behavior.   the A/P expects a final mode determination to be done on that segment, and needs a button push to make that happen. 

 

Edited by PaulM
  • Like 1
Link to comment
Share on other sites

This thread was started on S55X specifics.. and then G1000 behavior w/S55X was added. 
the 55x has internal GPSS steering, so we fly that in NAV-NAV mode (two pushes of the nav button).  With a GPS we will be in nav mode for the feeder, through the procedure turn and keep in NAV mode towards the FAF. 
Questions of A/P behavior have evolved since approach operations with a GPS/NAV unit are done differently from the VOR/LOC era of flying when these A/P's were designed.     You used to have to switch between HDG & NAV multiple times in a regular approach either vectors or full procedure.   
We also see generational changes in A/P's.. You used to have to hit APR (King, century, early Stec) to get the APR mode + GS capture.   Stec has changed to using NAV with the precision approach indicator from the NAV unit to go directly into APR mode.. the 55X still includes a separate APR button,.. the S60 doesn't.  
What I am seeing with RNAV and ILS approaches is that vectors to final (or any other process) needs the button (NAV or APR) to be hit on the segment right before the FAF.   Normally with VTF you are vectored to the segment before the FAF, LOC or LP is active and the AP will go right to APR mode. 
If for whatever reason you are vectored to a segment before the FAF for an RNAV or ILS and the nav radio isn't in the LOC/LP mode yet, you are going to have to push the button again when on the FAF segment. 
GPSS in your system is VTF as far as the autopilot is concerned, so your normal process is GPSS/VTF until the NAV indicates  it is in precision mode.      GPSS in the 55X is an extended NAV mode..   What I see as a universal rule is to push the button (NAV/APR) on the segment to the FAF and you will always get the desired behavior.   the A/P expects a final mode determination to be done on that segment, and needs a button push to make that happen. 
 


Your post brings out an important point about flying with an autopilot - you better know how it works.

I have flown as a safety pilot over the years with pilots who still didn’t fully understand what parameters needed to be met or the buttonology needed for an approach. I was in the same boat when I moved over to the Aspen and GTN, even though I had flown with the STEC 60 for 14 years.

The STEC manual for the 60 didn’t help either since it hasn’t been updated to reflect the newer technologies that can drive it.


Sent from my iPhone using Tapatalk Pro
  • Like 1
Link to comment
Share on other sites

8 hours ago, Marauder said:

 


Your post brings out an important point about flying with an autopilot - you better know how it works.

 

Totally agree.

@PaulM.  I have an Aspen Pro, IFD540 and 55x.  The 55x behaves exactly as you describe in that I have to arm APR by pressing the button in all regimes for the Glideslope to work .  I usually do this as I am approaching the IAF and below the Glideslope intercept.

Victor

Link to comment
Share on other sites

6 minutes ago, Mooney in Oz said:

@PaulM.  I have an Aspen Pro, IFD540 and 55x.  The 55x behaves exactly as you describe in that I have to arm APR by pressing the button in all regimes for the Glideslope to work .  I usually do this as I am approaching the IAF and below the Glideslope intercept.

I think we are writing the 2017 manual for the Stec... the original was based in the pre GPS era..   A modern interpretation would say fly GPSS or HDG until the FAF, and press X button outside the FAF for the final approach..  They just have not updated the documentation.    A cynic would say that they could update the software to modern standards and auto-sequence from NAV to APR upon the receiving of the precision signal..  But for now.. press that button.   I'm going to see if the Max Trescot books brought this up... they have some stuff about KAP140's.. 

I was used to always pressing APR on the last segment.... it was just that the manual for the 55x said just hit "nav".. so we were working out why that worked.. and should we use NAV or APR... .. doesn't matter.. just hit a button on the before the FAF.  

  • Like 1
Link to comment
Share on other sites

  • 2 months later...

Paul,

that might actually be a very good idea to kind of write the manual for them, how about collecting the procedures you guys use successfully for us others to reference to, verify and confirm they work with our setup as well? I've seen procedures written up for airliners for instance which are next to foolproof in a list form which actions to perform at what point. Never had a problem flying any of those airliners in the sim thereafter (was my job for a while to test sims) but this little GA AP seems to defy this kind of logic, my take still is it is because we are lacking the proper procedural narrative on how exactly to get it to do what we want.

I had one interesting suggestion the other day from someone else who flies one with an Aspen, just as an example.

The Aspen has it's own GPSS mode which in turn drives the HDG mode on the AP. What he does when he wants to intercept an ILS out of GPSS is that he concluded that the STEC 55X knows how to intercept from HDG but not from GPSS, so he drives GPSS over the Aspen which makes the AP believe he is following a heading signal, then presses HDG and NAV to arm the Localizer intercept.

It appears to me that most people nowadays do write their own books on it, as the one we got with it is outdated.

Link to comment
Share on other sites

3 hours ago, Urs_Wildermuth said:

The Aspen has it's own GPSS mode which in turn drives the HDG mode on the AP. What he does when he wants to intercept an ILS out of GPSS is that he concluded that the STEC 55X knows how to intercept from HDG but not from GPSS, so he drives GPSS over the Aspen which makes the AP believe he is following a heading signal, then presses HDG and NAV to arm the Localizer intercept.

What I suspect that Aspen person is seeing is the issue that we cover above..   The S-tec really wants you to hit a button on the segment outside of the FAF... using Aspen GPSS & HDG (VTF from the S-tec point of view).. and then hitting NAV is pressing that button.     Using the 55X GPSS mode (NAV NAV) goes all the way to the FAF, but you think, I'm in NAV mode, I don't have to press anything... but the 55x wants another NAV push, or APR push to finalize the mode settings, look at the inputs and select APR/GS. 

I just flew a GPSS LNAV+V approach to minimums and I used the APR button to arm the GS capture.    I have not yet done an ILS where the procedure turn terminates at the FAF..     That might trigger a default 45deg intercept depending on where the GPS switches from GPS to LOC.   I remember once upon a time blowing through the localizer after a GPSS procedure turn when I was transitioning, but that was an older rev of the G1000 software, and I was very new to the systems. 

  • Like 1
Link to comment
Share on other sites

A couple of things I suspect may be happening.

1. Everyone should determine at what revision level the firmware in the Fifty-Five X is operating. I don't know if this would effect these controls or not but there must be differences in operation of the different revision levels.

2. What Navigation sources are being used? WAAS, non-WAAS, VOR, other GPS. These all may have effect on the A/P 

3. Does your GPS automatically switch from GPS to VLOC? I believe there is a LOC flag from the GPS that (if connected) will trigger the APR mode on the A/P.

4. According to S-Tec NAV is used to Intercept and Track a VOR course.

5. According to S-Tec NAV APR is used to Intercept and Track a LOC and VOR front Course INBOUND.

6. GS is activated automatically after certain conditions are detected. Pressing APR when the GS is active will disable it.

7. Prior to inbound course intercept, depending on conditions, pressing the APR will force the A/P to high sensitivity of intercept and CDI needle deflection.

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.