Results 1 to 3 of 3

Thread: Boeing VNAV

  1. #1
    JAMES WEBSTER
    Guest

    Boeing VNAV

    Hi guys,

    I have noticed that the Aircraft can some times fly through the VNAV limit of
    250Kts below FL100 in the climb. Sometimes to 270Kts. Flaps retracted on
    schedule etc. Is this an issue in the aircraft.txt in the CDU?

    James


  2. #2
    Enrico Schiratti
    Guest

    Re: Boeing VNAV

    > I have noticed that the Aircraft can some times fly
    > through the VNAV limit of
    > 250Kts below FL100 in the climb. Sometimes to 270Kts.
    > Flaps retracted on
    > schedule etc. Is this an issue in the aircraft.txt in the
    > CDU?


    If it is doing 6000 ft/minute in climb and it is doing more
    than 250 knots, then you might consider reducing the climb
    thrust a bit... i.e. use CLB-2 or derate it. Some
    flightmodels are overpowered.

    Ciao

    Enrico


  3. #3
    Michel Vandaele
    Guest

    Re: Boeing VNAV

    Hi Enrico,

    Additional with my émails concerning the vnav thing, I receive the info from

    the real life, that VNAV is maintaining the set mcp speed (V2+10 or 20) till

    the flap retraction altitude.
    When reaching that altitude the speed bug is always set to VREF+100.
    In the case of the B744 (from 270.000kg T/O weight on, that's higher than
    250 knts with a clean aircraft).
    Therefore crew has to ask permission for height speed to the ATC.

    As you know, actually you set the speed directly to 250 kts in PM, once A/P

    is activated.

    Hope this helps a little to understand the complex working of VNAV in B744


    Ciao

    Michel

    "Enrico Schiratti" wrote in message
    news:384363.77131@wb.onvix.com...
    >> I have noticed that the Aircraft can some times fly
    >> through the VNAV limit of
    >> 250Kts below FL100 in the climb. Sometimes to 270Kts.
    >> Flaps retracted on
    >> schedule etc. Is this an issue in the aircraft.txt in the
    >> CDU?

    >
    > If it is doing 6000 ft/minute in climb and it is doing more
    > than 250 knots, then you might consider reducing the climb
    > thrust a bit... i.e. use CLB-2 or derate it. Some
    > flightmodels are overpowered.
    >
    > Ciao
    >
    > Enrico
    >



Similar Threads

  1. VNAV speed?
    By Tarzan737 in forum PM Boeing FMC/CDU
    Replies: 1
    Last Post: 01-08-2011, 11:38 AM
  2. mode “VNAV”
    By wsixpo in forum PM Boeing FMC/CDU
    Replies: 4
    Last Post: 03-17-2010, 07:00 PM
  3. Boeing VNAV Behaviour and FP import
    By Charalampos Perivolas in forum PM General Q & A
    Replies: 3
    Last Post: 01-12-2006, 07:06 PM
  4. Test instead of VNAV on GC
    By Steve Becker in forum PM General Q & A
    Replies: 5
    Last Post: 02-01-2005, 01:44 PM
  5. Vnav Descent Again.....
    By Eddie Armaos in forum PM General Q & A
    Replies: 7
    Last Post: 11-14-2004, 07:50 PM