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Thread: Using the TOD and BOD markings for the decent profile

  1. #1

    Using the TOD and BOD markings for the decent profile

    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

  2. #2
    ping ping (need 10 chars to post)

  3. #3
    Do you have the AP in LAT:NAV and VER:ARM?

    Have you entered altitudes into the flight plan on the EFIS?
    Rob Hickman
    Advanced Flight Systems Inc.

  4. #4
    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

  5. #5
    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

  6. #6
    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.

  7. #7

    Success

    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

  8. #8

    Follow up questions ...

    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

  9. #9
    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.
    Highest Regards,

    Noah F
    RV-7A
    Rhode Island

  10. #10
    Nelson,

    On the flight plan page each waypoint has the following information:

    • DTK (Desired Track)
    • VSR (Vertical Speed Required)
    • DTW (Distance To Waypoint)
    • ETE (Estmated Time Enroute)


    If you maintain the VSR once you reach the TOD then you will obtain the same results as using the VFLP mode. Coincidently, at the TOD the VSR should match your current VSPD setting. However, VSR is continuously calculated from your current position so prior to TOD it will be less than your VSPD setting and after TOD it will increase if you do not start your descent.

    I hope this helps.

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