Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: MCP Problem

  1. #1
    Our new friend needs to reach 10 posts to get to the next flight level
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    MCP Problem

    Good evening,

    I try to explain my problem.
    When I'm engage VNAV after Takoff (no matter at what altitute), the aircraft autopilot executes a "descent" before climbing again.
    I have tried many things. But no luck. Maybe someone can help?

    I'm using the PM MCP and the CP MCP Hardware

    Thank you
    Best regards
    Norbert

  2. #2
    500+ This must be a daytime job Sean Nixon's Avatar
    Join Date
    Jun 2008
    Location
    EGNT
    Posts
    713
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    I have experienced this too, although it seems random and I haven't yet figured out under what circumstances it occurs. Is it happening all the time for you?

  3. #3
    Our new friend needs to reach 10 posts to get to the next flight level
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Quote Originally Posted by Sean Nixon View Post
    Is it happening all the time for you?
    Yes, all the time.

    Thank you for your answer Sean!

  4. #4
    75+ Posting Member
    Join Date
    Jan 2007
    Location
    Spain
    Posts
    146
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Quote Originally Posted by Norbert Woeller View Post
    Good evening,

    I try to explain my problem.
    When I'm engage VNAV after Takoff (no matter at what altitute), the aircraft autopilot executes a "descent" before climbing again.
    I have tried many things. But no luck. Maybe someone can help?

    I'm using the PM MCP and the CP MCP Hardware

    Thank you
    Best regards
    Norbert

    Have you checked if your first waypoint altitude restriction is not lower than the altitude you are at when you enhage the VNAV?

    Peter

  5. #5
    Our new friend needs to reach 10 posts to get to the next flight level
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Yes, Peter. All checked. Thank you for your answer.

    Best regards
    Norbert

  6. #6
    150+ Forum Groupie flightdeck's Avatar
    Join Date
    May 2007
    Location
    LOWW
    Posts
    175
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Hi Norbert,
    what about the trim?
    What is the trim reading, when you engage the VNAV?
    Are the trim wheels spinning during the initial dive?
    Cheers
    René
    René

  7. #7
    Our new friend needs to reach 10 posts to get to the next flight level
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Quote Originally Posted by flightdeck View Post
    Hi Norbert,
    what about the trim?
    What is the trim reading, when you engage the VNAV?
    Are the trim wheels spinning during the initial dive?
    Cheers
    René
    Hello René,
    hm, never have thought about that. Will test it at the weekend. I'm away from home till suterday.

    Danke und Grüße nach Wien
    Norbert

  8. #8
    25+ Posting Member



    Join Date
    Oct 2007
    Location
    Zurich
    Posts
    56
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Quote Originally Posted by Peter Nielsen View Post
    Have you checked if your first waypoint altitude restriction is not lower than the altitude you are at when you enhage the VNAV?

    Peter
    Hello Norbert,

    this is the important answer! Have a look at the first waypoints on your FMC, perhaps

    XXX 150/2000
    XXY 175/3500
    XYY 230/5000
    YYY 250/10000

    if you are between the second and the third waypoint already up to let me say 7000ft and you engage VNAV then AP will force ou down to 5000ft, thats why you dive.
    Two things to do:

    modify your waypoints [B]before take off[/B when you know you will engage very early VNAV

    ]XXX 150/2000A
    XXY 175/3500A
    XYY 230/5000A
    YYY 250/10000A

    behind the altitudes put an "A", stands for at or above; this means the given altitudes figure like minimums. By the way you can do this as well in the descent. Then you have to put a "B" behind the altitudes. Means at or below.

    second way: apply a desired Altitude for instance 15000 activate VNAV and ALT INTV (if you have cp flight MCP pro); this is a second way to modify your climb.

    If been told ind daily practice the VNAV is rarely used, usually only in the last tthird or quarter of the climb. Up to there they conduct the flight in MCP mode altitude with SPEED, ALT and V/S.

    hope this helps

    Bernhard (LSZH)

  9. #9
    25+ Posting Member
    Join Date
    Feb 2008
    Location
    Italy
    Posts
    74
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Hi Bernhart,

    your explications in my opinion is not Procedurally correct. I'll explain why.
    If you have in your climb profile an HARD restriction to a WP, like many SID had, you cant'use the A or B (soft Restrictions) because you must stay at a specified Altitude and/or Speed. The same things about ALT INTV, because you cancel the Restriction on that WP.
    Finally according to many SOP by different Airline, the Climb phase is flown at VNAV or LVL CHG: That's because the SPD/ALT/V/S don't protect you by the Stall. So normally if you don't use VNAV you must use N1 - LVL CHG.

    Normally the VNAV is engaged after cleaned the airplane. You can see that on the Normal Procedure Manual. Or you may use the VNAV at the acceleration Altitute. Ex: on the VNAV CLB Page, LSK 3 set 210/3000 (3000 feet AGL) and on LSK2 250/ as target speed. when you reach Fl100 you resert Trget Spees to ECON (the Speed calculated by the FMC)..

    I hope I explained that clear.

    Regards
    Arnaldo Vacca

  10. #10
    Our new friend needs to reach 10 posts to get to the next flight level
    Join Date
    Feb 2007
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: MCP Problem

    Quote Originally Posted by bravolima View Post
    this is the important answer! Have a look at the first waypoints on your FMC, perhaps

    XXX 150/2000
    XXY 175/3500
    XYY 230/5000
    YYY 250/10000

    if you are between the second and the third waypoint already up to let me say 7000ft and you engage VNAV then AP will force ou down to 5000ft, thats why you dive.
    Two things to do:

    modify your waypoints [B]before take off[/B when you know you will engage very early VNAV

    ]XXX 150/2000A
    XXY 175/3500A
    XYY 230/5000A
    YYY 250/10000A

    behind the altitudes put an "A", stands for at or above; this means the given altitudes figure like minimums. By the way you can do this as well in the descent. Then you have to put a "B" behind the altitudes. Means at or below.
    Hello Bernhard

    thank you very much for your very kind answer. But it's a pitty, I have checked it with a "A" behind the altitutes. So this can't be the reason for the automatic descent.

    Best regards
    Norbert

Page 1 of 2 12 LastLast

Similar Threads

  1. GS problem
    By Abrupto in forum PM General Q & A
    Replies: 12
    Last Post: 08-28-2010, 06:32 AM
  2. Ias Problem
    By AchillesP in forum PM General Q & A
    Replies: 7
    Last Post: 07-16-2008, 02:25 PM
  3. PM FCU Problem
    By imported_darrens in forum FS2Phidget Users
    Replies: 14
    Last Post: 11-09-2005, 07:59 AM
  4. Problem with 3.0.9
    By Chris97b in forum FS2Phidget Users
    Replies: 3
    Last Post: 05-28-2005, 07:10 PM