However, I have seen folks talk about how the IFD can "round the corners" of turns when transitioning from one way point to the next so as to make tight turns easier.  However, when I was out trying a few flight plans and approaches, I noticed that I didn't see the candy-cane rounding out the corners of the turns, and the Trutrak flew exactly what was on the screen... it flew to the waypoint, and then as it passed over, it started the turn (in this case a pretty sharp 130 degree turn back, intercepted the course and flew it like normal.

I am very very new to using an IFD as well as flying with an autopilot, so please forgive my lack of experience. Is there some feature I need to turn on, or do something different when I am setting up the flight plan in the FMS to get the IFD to "round the corners" of the turns?

thanks!

"The GPSS mode allows the autopilot to follow a direct-to or multi-leg flight plan from an IFR GPS. This mode uses ARINC 429 data. This mode will anticipate upcoming turns, rounding the corners instead of overshooting the next course. It will also fly procedure turns and approaches. This mode is accessed from the track selector mode by a momentary press and release of the MODE button on the autopilot. When in GPSS Mode, the autopilot display will show GPSS on the display." trutrak

From your description, it sounds like the 130 degree turn was the reason that you didn't round the corner.  As you said, though, the map showed exactly what was going to be flown.

I believe that was it AviSteve!  Here is what the flight looked like:

https://cl.ly/0P2z0C1W071v

We were direct WITIV on autopilot.  it flew to WITIV, then right past it, it started the right hand turn (the countdown timer popped up beforehand).  it made the sharp turn back and intercepted the course to KAYAC.  Once it got to KAYAC, it looks like it actually "rounded the corner" as one would expect.  From looking at the overlay on CloudAhoy, it seems its working as expected.  I just wasn't aware it wouldn't round the corners on turns over 130...but that makes sense after thinking about it.

Heres the entire flight on Cloudahoy:  https://www.cloudahoy.com/debrief/?key=MOfHjPq5ngqnhkQ05D7E

I only have about 7 hours behind the IFD, but I am really loving it so far.  

Which TruTrak are you using?

We have the Gemini AP in our Glastar and an IFD-540 and it works quite well. As others have noted, on larger turns it won't round it, but those aren't very common.

We used to have the old TruTrak ADI Pilot II and it wasn't as smart so it wasn't rounding the corners.

Jeremy

Jeremy,

I am using the new TruTrak Vizion that recently got STC'd for Cessna Cardinals.  AviSteve was correct, its working normally, my turn was just over too much angle for the IFD / Trutrak to to do the corner rounding.  All other turns, below the (I think 130 degrees) do get their corners rounded, and the TruTrak is able to make the turns commanded by the IFD with no issues or overshoots.  

I flew it a bit today, and it worked exactly as expected.  It was just my total newbness of never having all this technology that was the problem :-)

Yep, I was wrong about the 120.  I always get these two values mixed up...  On any course change greater than 135 degrees, the FMS will treat the waypoint as a flyover.  Normally, you'll get a waypoint alert 10 seconds prior to the start of the turn.  However, on course changes greater than 120 degrees, you'll instead get the alert 30 seconds prior.

I don't remember why/how we came up with the 135 value, but the 120 value is straight out of the regs (DO-229D MOPS).

Turn transitions are computed for turns up to 135 degrees.  The map shows the turn transitions. However, deviations are provided to the active leg, not to turn transitions.  So if you're hand flying by monitoring a CDI, as you start an early turn the desired track stays the same and the needle will start to move.  At the mid point of the turn, the active leg will sequence, the new desired track will be set, and the needle will start to move back toward center as you approach the new leg.