Flying ILS with Sorcerer

[sj_rv7]

Today I programmed the ILS in my GNS480 and engaged the Sorcerer. When I press the GPSV button I get a GPSV-FLG indication. It does not capture the glideslope. If I engaged the GPSS it follows the loc pretty well and I'm using vertical speed select for the glideslope.

How do I get it to couple to the ILS? Can't find anything in the manual for this.

Steve
RV7

[PhantomPholly]

GPSS is a GPS-only mode.

See "NAV/LOC Course Mode" in the User's Manual (http://www.trutrakflightsystems.com/documents/SorcererOperationManual.pdf) on page 5. Basically, once you are on a heading to intercept the Localizer and are below the Glideslope, you will need to switch the autopilot mode to Localizer mode; adjust the intercept angle if not 30 degrees, and select Altitude Hold. This will "arm" the approach mode, and once the needle starts moving towards center you will see the autopilot start changing course to intercept.

If you are above the Glideslope, or if you neglect to select Altitude Hold, it will not begin the descent.

However, from personal experience I typically found that using Localizer only and manually dialing in a vertical descent rate gave a "nicer" approach - the autopilot will tend to "hunt" for the glideslope, and the "ideal" vertical activity setting on the final approach may be very different than the "ideal" setting in cruise.

[TrutrakTech]

PhantomPholly to the rescue again!

Steve, you'll need to push the NAV button on the Sorcerer to engage the analog mode. It will ask you for the course, use the knob to select. Push the knob to move the cursor to intercept angle. Once you've set the angle, push the knob again. This will put it in that mode. As Pholly said, make sure you're in Alt Hold mode or the AP will not capture the glideslope.

The GPSS and GPSV modes work for LPV approaches. Thanks!

[sj_rv7]

Thank you. The ILS worked great today. Next step is precision GPS.

Steve

[Dane]

Too bad there is no way to capture the glide slope via vertical speed from above. The steps you have to go through to arm the glide slope seem a bit awkward. Basically you have to be in level flight, in Altitude Hold, below the glide slope, for it to arm. Not all approaches lend themselves well for this.

[PhantomPholly]

Too bad there is no way to capture the glide slope via vertical speed from above. The steps you have to go through to arm the glide slope seem a bit awkward. Basically you have to be in level flight, in Altitude Hold, below the glide slope, for it to arm. Not all approaches lend themselves well for this.

Well, for what it's worth if you are 5 miles out you could descend a bit more than one dot below glideslope and then just hit Altitude Hold. That should cause it to arm, but I'm not positive.

Also, for what it's worth my comments on the ILS over correcting might have more to do with the airplane I was in than any weakness in the autopilot. My experience was in a Lancair 235 with a fixed pitch prop and a 118hp motor - an airplane that is renowned for it's pitch sensitivity. The TT was "tuned" for pleasant flight at 180mph, and thus probably was NOT "tuned" for slow flight.

Bottom line? Always test your systems in all regimes of flight on a nice sunny day before you ask them to do their job in the soup.

[Dane]

I had a talk with the folks at the T/T Booth in Oshkosh and learned a thing or two that I thought I'd pass on.

First of all; The Autopilot has to be in Altitude Hold (with a Glide Slope signal present) for something like 7 seconds for the Glide Slope to arm. There is no diving down to capture the glide slope.

Second; if you try to arm the glide slope without a signal, you will just get a Flag message. The glide slope does not go from Flag to Arm on its own.

So here's the scenario, and let’s just assume a GPS Approach with a WASS Navigator (GPS Glide Slope). On Downwind if you push the GPSV button, you will get a 'GPSV Flg' message and the autopilot will never capture the Glide Slope. On Final, (outside the final approach fix) when the GPS Glide slope is present but all the way at the top of the case (it's the purple dot on my display) pressing GPSV shows 'GPSV Hld'. A few seconds later (maybe 7 seconds) I get an audio alert that says "Glide Slope Armed" and the display goes to 'GPSV Arm'. As the glide slope comes down and reaches center I get another audio alert that says "Glide Slope Coupled". The display on the front panel changes again to indicate that it is tracking the Glide Slope and down we go, following the GPS Glide Slope.

It works more or less the same with the ILS Glide Slope. It won't arm if the signal is flagged and must be in Altitude Hold for 7 Seconds while below the Glide Slope, to arm, and couple to the Glide Slope.

If I am wrong about this, perhaps someone will set me straight, but this is my understanding of the system as of 6:00 PM on August 1st 09.

Hopefully this information will appear in a future version of the Instruction Book.

[PhantomPholly]

Yes, it seems a bit awkward.

As long as you have the ILS needles on your HSI, you can always just dial in a vertical speed and fly the approach. No waiting to "arm" using that method.