GTN-650 and SV Interaction With Go Around Button

[Dynon101]

Any GTN-650 and SV drivers out there who can help me understand the integrtion???

My airplane is close to flying and I am reading the SV and GTN-650 Pilot User Guide and "chair flying" the integrated system and trying to figure out what this magic will do.

Firstly, It seems that the NOSE UP button on my SV Autopilot panel is considered the "Go Around button"? (SVPUG 8-16)

It is a bit more complex when the GTN gets into the mix...The GTN-650 P1002 pin 10 is the "System ID Program" and I can tell the GTN that when this pin sees ground it will activate the GA mode so I have the wire from that pin connected to a "Remote Go Around" push button on my grip.

I am curious what the GA button will do with the SV-1000 integration with the GTN-650.

Let say I have selected the GTN to be my nav source and am flying a ILS and GS and I am inside the FAF with the GS captured.

I assume that when the GS is captured then the SV ALT level off function will not respect the altitude preselect...if so I assume it would be good practice to set the ALT BUG to the Missed Approach altitude?

So what happens when I get to DA and press the GA button? The SV Pilot User Guide 8-27 states "Upon activation of the GA function
the active vertical autopilot mode switches to VS with the default climb vertical speed target or IAS with the current indicated airspeed target. The lateral autopilot mode switches to TRK with the current track."

I assume that description is with respect to a "generic navigator". Does anyone know what happens with the GTN-650 with a Remote GA button?

I assume the vertical guidance will become a VS climb based on the programmed VS speed in the SV AUTOPILOT SETUP > PITCH AXIS page (IE 500 FPM)?

If the HSI source is still selected to GTN then would the course guidance become NAV tracking to the Missed Approach course or will it really simply just fly TRK until the pilot selects some kind of LNAV mode?

I assume that the HITS picture on the PFD will change from the descending boxes and then after the GA button is pushed SV will simply show a trail of level boxes up at the Missed Approach Altitude and show the course to the MAP...in other words the climb portion of the Missed Approach is all me and I am looking up to see the Highway course at the Missed Approach Altitude??

Thanks for helping me understand this system!!!

 

[krw5927]

Let say I have selected the GTN to be my nav source and am flying a ILS and GS and I am inside the FAF with the GS captured.

I assume that when the GS is captured then the SV ALT level off function will not respect the altitude preselect...if so I assume it would be good practice to set the ALT BUG to the Missed Approach altitude?

You got it.  If you're using the autopilot for lateral and vertical guidance on this approach, you would begin at some IAF presumably in NAV+ALT hold mode to follow the GTN's guidance laterally at the initial altitude.  You would arm "VNAV", so that the autopilot will start down the glideslope once it is captured.  Once the autopilot transitions to VNAV mode, it will ignore the altitude bug. It can be a very useful thing at this point to pre-select your missed altitude with the altitude bug - that way when you go missed and hit the "nose-up" button, the AP will climb at your default rate and capture this altitude automatically.

So what happens when I get to DA and press the GA button?  The SV Pilot User Guide 8-27 states "Upon activation of the GA function
the active vertical autopilot mode switches to VS with the default climb vertical speed target or IAS with the current indicated airspeed target. The lateral autopilot mode switches to TRK with the current track." 

I assume that description is with respect to a "generic navigator".  Does anyone know what happens with the GTN-650 with a Remote GA button? 

When you hit the GA button on the 650, the 650 will respond and give guidance to the missed approach point and hold.  The autopilot however, will ignore this and happily fly straight ahead just as described in the manual until you tell it once again to follow NAV from the 650 (just hit the "NAV" button). 

Keep in mind of course that because we're talking specifically about an ILS approach, you'll also be switching between GPS and VLOC modes in the 650 prior to the FAF and back again at the MAP (the 650 can do this automatically).  You'll get the process down with practice.

I assume the vertical guidance will become a VS climb based on the programmed VS speed in the SV AUTOPILOT SETUP > PITCH AXIS page (IE 500 FPM)?

Yep.

If the HSI source is still selected to GTN then would the course guidance become NAV tracking to the Missed Approach course or will it really simply just fly TRK until the pilot selects some kind of LNAV mode?

As above, it'll fly TRK until selecting "NAV" for the lateral autopilot mode.

I assume that the HITS picture on the PFD will change from the descending boxes and then after the GA button is pushed SV will simply show a trail of level boxes up at the Missed Approach Altitude and show the course to the MAP...in other words the climb portion of the Missed Approach is all me and I am looking up to see the Highway course at the Missed Approach Altitude??

Thanks for helping me understand this system!!!

Yep.  I didn't personally find HITS all that useful for IFR, so I turned it off.  You're required by regs to follow needles and altitudes, and for me the HITS boxes just added clutter.

 

[Dynon101]

KRW5927,

This is really helpful to my "chair flying" exercise and understanding of the integration of the GTN and the SV. THANKS for your time!!!

 

[krw5927]

Sure thing. I think the reason Dynon programmed the go-around mode to fly TRK instead of immediately switching back to NAV is because for the default obstacle departure procedure you are expected to fly runway heading to an altitude of 400' AGL prior to turning on course (at a minimum climb gradient too).

That's just a guess though.