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  • Convergence vs converg angle

    Hi,
    I am really confused on these 2 things:

    When I see a question like this:
    A Lambert conformal conic chart has a constant of the cone of 0.80. A straight line course drawn on this chart from A (53?N 004?W) to B is 080? at A; course at B is 092?(T). What is the longitude of B?

    I assume 92-80 is 12 being the conversion ANGLE. but, its actually the convergency....and a formula convergency = CH long x Constant of the cone is used.

    Other times I see a similair question maybe not specifying a Lamberts, maybe specifying a grid, or no chart mentioned at all and 12 will turn out to be the conversion ANGLE ( IE inbound track 90 degrees and true track 102 degrees ) and convergency would in fact be 24 degrees.

    How do we know which one to choose? seems comletely arbitrary...

  • #2
    Re: Convergence vs converg angle

    Hi,

    Convergency is the amount by which a great circle track direction changes.

    Conversion angle is the angle between the great circle track and the rhumb line track.

    Baz

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    • #3
      Re: Convergence vs converg angle

      Ok Thanks Baz,

      Hopefully that helps.

      Comment


      • #4
        Re: Convergence vs converg angle

        How about here ( if u have a moment )

        The automatic flight control system (AFCS) in an aircraft is coupled to the guidance outputs from an inertial navigation system (INS). The aircraft is flying between inserted waypoints No. 3 (55?00'N 020?00'W) and No.4 (55?00'N 030?00'W). With DSRTK/STS selected on the CDU, to the nearest whole degree, the initial track read-out from waypoint No. 3 will be:

        answer

        The conversion angle is 1/2 convergency.

        Conv= 10 x sin 55 = 8 degrees
        Conv Angle = 1/2 x 8 = 4 degrees

        Convergency is the amount by which the Heading will change if you follow the GC track. So at 20W TRK 274 , at 25W TRK 270 and at 30W TRK266

        Its the conversion angle thats applied to the Rhumb line track not convergency.


        Is not the INS , in this mode, showing GC tracks between waypoints? So how is the last line correct?
        This is what messes me up

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        • #5
          Re: Convergence vs converg angle

          Originally posted by Baz View Post
          Hi,

          Convergency is the amount by which a great circle track direction changes.

          Conversion angle is the angle between the great circle track and the rhumb line track.

          Baz
          However this now makes sense. so...

          Comment


          • #6
            Hello,
            Somebody can help me?
            I tried this one
            A Lambert conformal conic chart has a constant of the cone of 0.80. A straight line course drawn on this chart from A (53
            Last edited by Bob747; 01-10-2018, 10:12.

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