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John and Bill,
I have about 700 hours behind a triple display Chelton with a TruTrak
Sorcerer autopilot.
My experience is that I fly the approaches (ILS, VOR, GPS) with the
Sorcerer in GPSV mode. The Chelton then drives the Sorcerer. Use the
altitude select on the Chelton to track down to the altitudes that ATC
gives you. When you level out at the approach altitude, turn off the
altitude hold and the Chelton then feeds the data to the Sorcerer to fly
the descents. The Chelton will display the approach altitude above the
altitude strip on the right side. Note: if you are tracking on
heading also turn off the heading. Both of these are turned off by
pushing the prompts "LNAV" and "VNAV" in the upper left of the screen.
Disengage the LNAV about 20 degrees before intercept as ATC is turning
you to intercept the inbound course. Disengage the VNAV when you are
ready to track vertically inbound.
The Sorcerer then flies the approaches maintaining both vertical and
horizontal axis. You must also dial in the ILS from the Garmin 430 or
similar. Then set the OBS on the Chelton so the needles are
appropriate. Do this when you first pick up the ATIS telling you what
approach is being used. Also select the appropriate approach in the
Chelton and Garmin 430 at this time.
So let the GPSV mode in the Sorcerer fly the approaches and you verify
everything is correct with the needles displayed on the Chelton. It
will fly right down the boxes, perhaps not always exactly in the center,
but right down the approach course. Said another way, you are flying
WAAS enabled GPS for all approaches and verifying everything is a go
using the ILS/VOR/GS needles. You have 2 systems that had better be
displaying the same information.
Note: I also have WAAS on the Chelton. The system is terrific.
Carl Cadwell
Formerly IVP with 1000 hours now an Epic with 700+ hours.
John,
Don't know Chelton specifically, but generally speaking the EFIS HITS
approaches do NOT correspond exactly with the ILS or GPS glide paths -
they are typically based on a synthetic approach to the approach end of
the runway at a "standard" approach angle. Check your Chelton manuals
to confirm this.
In any event, the ONLY thing you should compare the approach to is the
glide path / course needles. If they stay centered, the TT is doing it's
job perfectly.
Regards,
Bill
John Hafen wrote:
Gents:
In my IVP, I have a Trutrak Sorcerer Autopilot wired to a Chelton twin
screen system.
I shot a few GPS approaches today and everything seemed to work ok,
except that the decent after the IAF seemed to lag behind the HITS green
squares. The plane was going down, on the "glide slope" but not as
aggressively as it should have. Kind of hanging out near the top, or
slightly above the green boxes. It was a GPS approach that I initiated
by hitting the GPSV button on the Sorcerer.
I know that altitude transitions can be made by airspeed, vertical
speed, or horizontal distance (VNAV). So if my descent was lagging, I
wonder if I need to go into Pitch Setup mode and play with the vertical
activity or vertical torque. Or some other parameter.
Or is there a way to specify a certain airspeed or V-speed for the
descent - or is it just supposed to center the boxes.
I apologize for rambling a little here. I suppose my fundamental
question is how to make the auto pilot fly the descent right in the
middle of the green boxes...... What Am I Missing?
Many thanks and Regards.
John Hafen
IVP N413AJ 175 hours
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