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Need Help with an ATPL question!

  • 07-07-2011 4:07pm
    #1
    GKJK
    Closed Accounts Posts: 54 ✭✭


    Ok Met question that I just cant seem to get here...

    You are planning a flight at FL 290, which of these upper wind and temp charts would be nearest to your flight level?

    a. 850hPa
    b. 300hPa
    c. 500hPa
    d. 700hPa

    anybody able to help??

    I tried the 27ft = 1hPa thing and could work it out

    Maybe I'm looking at it wrong!


Comments

  • #2
    Lustrum
    Registered Users, Registered Users 2 Posts: 759 ✭✭✭Lustrum


    The 300hpa chart roughly corresponds to FL300, there's doesn't seem to be any kind of formula to work it out, you just have to learn them.

    The decrease of 1hpa/27ft is only applicable at the lower levels of the troposphere, as you go up and air pressure decreases, the change of height per 1hpa increases eg. at MSL it's 1hpa/27ft, at FL180 it's 50ft/hpa and at FL390 it's 105ft/hpa (all rough figures).

    Write these down on a sticky and have them on the wall beside you:
    200hpa = FL390
    250hpa = FL340
    300hpa = FL300
    400hpa = FL260
    500hpa = FL180
    600hpa = FL140
    700hpa = FL100
    850hpa = FL50

    Any others you can interpolate between these and figure it out


  • #3
    GKJK
    Closed Accounts Posts: 54 ✭✭GKJK


    Lustrum wrote: »
    The 300hpa chart roughly corresponds to FL300, there's doesn't seem to be any kind of formula to work it out, you just have to learn them.

    The decrease of 1hpa/27ft is only applicable at the lower levels of the troposphere, as you go up and air pressure decreases, the change of height per 1hpa increases eg. at MSL it's 1hpa/27ft, at FL180 it's 50ft/hpa and at FL390 it's 105ft/hpa (all rough figures).

    Write these down on a sticky and have them on the wall beside you:
    200hpa = FL390
    250hpa = FL340
    300hpa = FL300
    400hpa = FL260
    500hpa = FL180
    600hpa = FL140
    700hpa = FL100
    850hpa = FL50

    Any others you can interpolate between these and figure it out

    ah yes now that you say that i remember a table in the book!!...though looking at it now it's a bit understated..they could have kind of drawn more attention to it!..how and ever thanks for the help!! :)


  • #4
    bombs away
    Closed Accounts Posts: 291 ✭✭bombs away


    there's a few questions in the exam that take information directly from that table so memorising it is a pretty good idea ;)


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