Using the TOD and BOD markings for the decent profile

[dnelson]

Hi AFS,

What do I need to do to get the AP to follow the TOD and BOD decent profile?

So far, my sequence is as follows: I've entered the flight plan into the GNS-430W, I can see the flight plan on the 4500, and the AP is receiving ARINC data from the EFIS. When I get within AWOS range, I go into the 4500's flight plan menu and select the runway. At this time, I see TOD, BOD, and the "feathers" for my selected runway on the 4500's map display. I also set the Minimums bug to pattern altitude. When I reach TOD, the AP continues to fly normally. At this point I disengage the AP and I manually fly the decent. BTW, this is for VFR approaches.

How do I get the AP to follow the TOD and BOD decent profile?

Equipment is: 4500EE w/ 8.08.12 firmware, GNS-430, AF-Pilot, and an AF-ARINC module.

I thought I had seen/read how this done somewhere but I can't seem to find it on the forums nor rev 7.4 of the EFIS's manual.

Thank you,
/\/elson

[dnelson]

ping ping (need 10 chars to post)

[Rob Hickman]

Do you have the AP in LAT:NAV and VER:ARM?

Have you entered altitudes into the flight plan on the EFIS?

[dnelson]

Hi Rob,

Next time I'm up, I'll verify the LAT:NAV and VER:ARM. Regarding the entered altitudes on the EFIS, I've set the Minimums bug to pattern altitude and the Altitude bug to my desired cruising altitude.

I did find the ILS training video:

http://www.youtube.com/watch?v=3EWVCERR0Is

Would my procedure generally be the same with the exception of not selecting the approach within the 430?

Thank you,
/\/elson

[dnelson]

Hi Rob,

Got some test flights in this weekend. I did verify that LAT:NAV and VER:ARM were displayed. Still, the A/P flew right over TOD and kept on flying straight and level. My procedures were as follows:

- Selected Direct-To on the 430 for T74.
- Set my ALT bug to 2500'
- Set my MINS bug to 1650'
- Verified LAT:NAV and VER:ARM
- Engaged the A/P, sat back, and looked for traffic
- Flew well past TOD before I manually took over to begin my descent

Thanks,
/\/elson

[chardks]

In the 4500, VER:FPL works just like VER:ARM in as it will capture the glide-slope and switch to VER:NAV. However, VER:FPL follows the flight plan altitude transitions instead of the altitude bug. Try it again but put the AP in VER:FPL mode.

[dnelson]

Hi chardks,

It worked liked like a charm! My procedure was as follows:

- Selected Direct-To on the 430 for my destination.
- Set my ALT bug to my current altitude.
- Set my MINS bug to 1650'
- Verified LAT:NAV and VER:FPL
- Engaged the A/P, sat back, and looked for traffic
- When I reached TOD, the nose gently went over for the descent. I controlled my vertical speed with the throttle.
- A bit before the airport (a couple miles?), the A/P leveled out at 1650'.

Thank you,
/\/elson

[dnelson]

Hi AFS,

I've been using the VER:FPL mode quite successfully. I've two follow-up questions when you get the chance:

- First, is there a shortcut method to selecting VER:FPL mode on the 4500? Something akin to moving the joystick upward to select VER:ALT (IIRC). I currently navigate through the menus: MAIN -> EFIS -> AP/?? -> VER -> FPL.

- What numbers do I need to fly manually in order to achieve the same results as if VER:FPL were flying?

Thank you,
/\/elson

[NoahF]

Ooh just saw this. Didn't know this was possible to do. If you are controlling vertical speed with throttle, then it would seem that the TOD & BOD are fixed lateral points in space? Or is the vertical speed controlled via the 430W? It would be very nice if the vertical FPL were joystick selectable. As a point of clarification, AFS seems to indicate that this is working off the internal flight plan, but Nelson is using the 430W's flight plan. In what box are TOD & BOD calculated? On the VNAV page of the 430W, you can input parameters about distance from the airport to reach XXX feet above the airport - does this establish the BOD? And also vertical speed can be input, which would seems to allow calculation of TOD. Is this where this is done?

Maybe I will just have to play around with this.

[chardks]

Noah,

TOD/BOD are calculated by the EFIS based on your current time to next waypoint, vertical distance between waypoints, and the vertical speed bug setting. TOD/BOD will move when the vertical speed bug is changed or there is a significant change in ground speed. It does not take your current altitude into consideration. All altitudes used in the calculations are from one waypoint to another.