lat/vert modes when engage AP

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APACHE 56
Posts: 29
Joined: Fri Mar 22, 2013 10:08 pm
Location: Merritt Island, FL

lat/vert modes when engage AP

Post by APACHE 56 »

There are several modes for the LAT/VERT AP which are explained (after a fashion) in the 2009 User Manual. My question is: when you engage the AP (I have a GRT AP and dual HX with a GTN 650) what mode should the LAT and VERT default to? You can press the softkeys and the AP modes show up (as I write this I can't recall what configuration mine went to) and you can change them which begs the question: should you change them and when.
Another question: If you are following a flight plan you have entered into the GTN, for example, which modes should the AP be in (relevant if different from question above).

I am getting my IFR skills dusted off and the "buttonology" of these systems is sometimes vexing. As an aside the GTN is dead simple but I am not sure that the GRT EFIS and AP are expecting me to press some key button at sine critical time.

thanks,
Don
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: lat/vert modes when engage AP

Post by Bobturner »

Don,
You are correct that there is a certain amount of button pushing. That is the price for all the capability. I have a Trio but controlling it from the HX should be the same as yours.
1. Push the right hand knob (knob, not button) once. This asks for the desired altitude (enter with right knob) and also brings up the autopilot menu. For lateral navigation using your gps select gnav; for vor, select enav; for flying a heading (e.g., vectors) select hdg (push left knob to center heading bug; rotate left knob to change). Vnav should be in alt.
2. Push the right knob again. It will ask for climb rate or airspeed to use, depending on setup programing. Adjust with right knob or choose preprogrammed buttons. Buttons also let you change to FD display.
3. Push right knob again. You should be good to go. Makesure the nav source matches what you told the autopilot.

I'll tackle approaches later, I need to run!
APACHE 56
Posts: 29
Joined: Fri Mar 22, 2013 10:08 pm
Location: Merritt Island, FL

Re: lat/vert modes when engage AP

Post by APACHE 56 »

BOB,
THANK YOU.
Eagerly awaiting the "approaches" tutorial.
DON
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: lat/vert modes when engage AP

Post by Bobturner »

Okay, first a correction. On the autopilot menu (after pushing right knob once) the vertical options are labeled VERT or something like that. You can select to climb at a desired VS (vertical speed), or a desired ASP (airspeed); AUTO is my default and it has you climb on an airspeed, but descend at a given VS. The last item in the list is VNAV; only use this to manually engage a glide slope.
Also, I have assumed your Garmin GPS uses the ARINC coupling to the HX. IF not, the gnav will not work. You can use enav and track the gps but you will loose the gps steering (anticipation) commands, nor will it do GPS LPV approaches. But I presume ARINC is hooked up.

1. Precision GPS (LPV) approach. Set up the autopilot as above, using gnav (gps), enav(vor), or HDG (vectors) to navigate from the initial approach fix toward the final approach. Before intercepting, push right knob once, select GPSV ARM from the list, push right knob twice to exit. Have your gps configured for the approach (I think you need to do this before arming the HX).
2. IF and only if you have the latest software, "Execute" will appear above a button. Push button to confirm. Older software this won't happen.
3.At final course intercept, autopilot will automatically go to gnav mode and turn on course; at glide slope intercept it will automatically go to VNAV mode, and will say "captured" on the upper right corner of the PFD. At GS intercept, autopilot will pitch down to track GS. You probably want to reduce power at this time to avoid excessive speed. Re-trim if needed (Trio will trim automatically).
4. At GS intercept and "capture", the word "Missed" should appear above the center button. More on missed approaches later. IF you see runway environment prior to DA, disconnect autopilot and land, assuming you have required visibility. You can set an altitude bug for the DA but this is for you only, the autopilot does not see it. In an emergency the autopilot will continue to fly the aircraft until it hits nose first on the runway.
NOTE: if you are using gnav to track from the IAF to the FAF, and there is a racetrack course reversal, the gps and autopilot will fly it without doing anything, as long as you only need one turn around the track. If you need to hold, push OBS on the GPS to suspend waypoint sequencing (set OBS to desired course, inbound). GPS will fly you in the hold.

ILS approach
1. Use gnav (gps), enav (VOR), HDG (vectors) to navigate from initial approach fix toward localizer.
2. Tune a nav source to the ILS frequency. This must be done first. Do not tune multiple radios to an ILS frequency (I think the default is to use #1 nav but this is confusing). The nav source does not need to be selected on the efis, use gnav if the gps is navigating, HDG if vectors, etc.
3. Push right knob once, select "ILS armed" from the list. Push right knob twice to exit.
4. The EFIS will scan all nav sources looking for an ILS.
5. It will attempt to set the course bug on the HSI to the final approach course. It will ask you to verify. If it's wrong go to HSI page and set manually.
6. Newest software only, "execute" appears. Push button to acknowledge you want to do the ILS.
7. As you approach the localizer, it will automatically switch over to enav, automatically select the nav source tuned to the ILS frequency, and track the localizer.
8. At glide slope intercept, autopilot will pitch down. Reduce power to maintain desired speed, re-trim if needed.
9. "capture" should appear in upper right, "missed" on bottom of page, of PFD.
10. When runway environment in sight with visibility minimums okay, disconnect autopilot, land by hand.

Non precision approaches (VOR, LNAV, etc).
Just fly these as if they were enroute flying. Use enav for VOR, gnav for gps (LNAV) (set up gps for approach). At each step down fix, push right knob, turn right knob to the new stepdown altitude, push right knob, set desired VS , push right knob to exit. Repeat for each step down fix.
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: lat/vert modes when engage AP

Post by Bobturner »

Missed approaches

1. At any time (even before takeoff) cycle thru "more" on main PFD until you see "set Missed alt". push button, dial in the missed approach altitude (this is not the DA (decision altitude), this is the altitude you will climb to for holding following a missed approach).

For miss following an LPV approach. To the best of my knowledge all gps LPV approachs have gps guidance for the miss. So to miss, just push the MISSED button on the EFIS (at any time), power up to climb (re trim if needed). As you pass the missed approach point the Garmin gps will go to "suspend". Push the OBS key on the garmin to un-suspend.
That's it. Autopilot will fly plane to pre-programmed altitude and hold. You probably want to power back once level.

Miss following an ILS:
This can be complicated, so I will use my home airport (LVK) as an example. Missed approach instructions are "climb runway heading to 1300', then climbing right turn to 3000' direct REIGA LOM, then direct TRACY intersection and hold". Now, my 420W has the following programed into it for the ILS miss: direct REIGA, then TRACY, hold. It does not know about the climb to 1300' before turning. Here's whats needed.
1. Same step one as above. At any time, on pfd, cycle thru options, find "set missed alt", push button, dial in 3000'.
2. Set up ILS approach as above. Make sure 420W is set up for ILS approach, too, since it will be used for the miss. SL30 will provide guidance during the approach.
3. AFTER GS intercept and the "Capture" appears, the autopilot is locked onto the ILS. Changing the options does nothing until MISSED is pushed. So after "Capture", push right hand knob once; from lateral options select HDG; turn left knob to put heading bug on runway heading (255 in this case). Push right knob twice to exit.
4. At DA or before, push MISSED on HX and add power. Autopilot will switch to HDG mode, and will start a climb for 3000'.
5. Passing 1300', in my case, I turn the left knob (heading bug) to the right. Plane will turn right. Continue turning heading bug to 075 (255 - 180 = 75), since I need to do a right 180 to head back to LOM. NOTE: do not turn bug too fast, too far. If I accidentally set it quickly to 090 the aircraft will turn left instead of right. It always goes the shortest way.
6. While turning I change the HX nav source from the SL30 to the 420W.
7. As the plane approaches a heading of 075, now and only now I push "OBS" on the 420W to "unsuspend" the gps. NOTE if I pushed it earlier it would draw a course line from that position to the LOM. I only want it to do that after the 180 turn.
8. push right knob once, change lateral navigation from HDG to gnav. Push right knob twice to exit. GPS will now fly the rest of the miss, including the hold.

Different approaches may require different variations, some may let you go to gNav immediately, etc.

This is a lot of stuff that needs practice, but after a while it all makes sense.
Last edited by Bobturner on Wed May 08, 2013 2:32 am, edited 3 times in total.
Bobturner
Posts: 444
Joined: Mon Mar 11, 2013 6:34 pm

Re: lat/vert modes when engage AP

Post by Bobturner »

Other notes:

In case it isn't obvious, you have to use the HX's HSI page to set the OBS for VOR tracking, or if using the gps in the OBS mode.

I like to climb on airspeed (not VS) to assure good engine cooling. But it is always the PIC's responsibility, not ATC's, to assure terrain clearance if IFR or at night. If in doubt use Vx.
Last edited by Bobturner on Wed May 08, 2013 2:33 am, edited 1 time in total.
APACHE 56
Posts: 29
Joined: Fri Mar 22, 2013 10:08 pm
Location: Merritt Island, FL

Re: lat/vert modes when engage AP

Post by APACHE 56 »

Bob Turner,
Thank you once again for the spot on tutorial. You saved me Avogadro's number in fuel cost. Flew today armed with you notes. Everything was as advertised.
I am in Central Florida (Space Coast) and we seem to have the corner on the World's Training market as we are sandwiched between Daytona and Miami. Being able to keep a vigil outside the cockpit without nav/alt worries is potentially life saving.
thanks again,
Don
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katieb
Posts: 141
Joined: Mon Dec 10, 2012 2:29 pm
Location: Shelbville, TN

Re: lat/vert modes when engage AP

Post by katieb »

Thank you Bob, that's an excellent explanation. I must admit I didn't read this thread in depth right away because I saw you had it handled. :D

I'm still working on an AP section for the HXr manual. The first part (Basic Modes & Annunciations) should be out this week. It will also apply to HX, but HX requires more button pushes than HXr due to HXr's flatter menu structure.
Katie Bosman
Pilot/Tech Writer
Jabiru USA Sport Aircraft
http://www.usjabiru.com
GRT Tech Support/Marketing 2012-2014
GRT Pilot Since 2008
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