Help with B787 autopilot

  • Hi, I need some help with the descent and landing phases using the B787 autopilot please.

    I read the tutorials and flew from Salt Lake City to San Francisco. I set a manual cruise alt (FL340) and Mach .82. All was ok during the climb and cruise.

    Just before the T/D point I set a lower speed of 280kts, and a lower altitude of 200Ft. The PFD showed "Hold" for speed and "VNAV SPD" for the vertical mode. The descent began as expected, however my altitude remained constantly above the Vertical Path indicator.

    When I activated Approach mode the Glideslope indicator remained below my descent altitude. At the airport I was 3000ft too high.

    Any ideas what went wrong here?

    I understand that the descent should start automatically when the VNAV path is intercepted, and it seemed to. But it didn't indicate VNAV Path, it was VNAV SPD ....I don't really understand what that is ....

    Finally, how do I change the cruise altitude in the flight plan, to get an accurate T/D position, like you can with the A320 INIT page? I couldn't find anywhere in the B787 FMS where this could be set.

    (Edit, I found the cruise alt setting on the VNAV page, perhaps that will help with the descent ....). I'm going to try the same flight again with the same flightplan and see if it makes a difference.

    Thanks for any tips and info!

    Further update! I completed the flight successfully ...starting the descent at the correct point obviously helped. This time the descent was below the VNAV path just before Localiser intercept, so I clicked Alt Hold and levelled off until the vertical path was centred, then clicked Approach mode and it went well from there.

    Its amazing to be able to learn about the differences between the Airbus and Boeing systems, thanks Aerofly!

    Edited 3 times, last by mcgregni (March 12, 2022 at 10:15 PM).