14 / 20

The position A (75°N, 34°E) of an aircraft and the position B (75°N, 50°E) of an NDB station are plotted on a polar stereographic chart projection and are connected with a straight line. Determine the true bearing from position B to position A, given:

Magnetic variation at position A: 32°W
Magnetic variation at position B: 60°W

  • A
    050º
    ​​
  • B
    278°
  • C
    082°
  • D
    310°

Refer to figure.

We can create a triangle made up by the North Pole (P), position A and position B.

The angle at P will be the difference between longitude of position B and position A.

  • Postion B = 50º; Position A = 34º
    Angle at P = 50º - 34º = 16º

Position A and B are located at the same latitude, which means: OA = OB. Therefore, the triangle APB is isosceles; and Angle at A = Angle at B.

The sum of angles of a triangle equals 180º. Consequently, Angle A and Angle B:

  • 180º - 16º = 164º
    164º / 2 = 82º

True bearing from position B to position A equals the angle measured clockwise from the True North at position B to the line connecting B to A. Angle at B = 82º. Therefore, True bearing from position B to position A = 360º - 82º = 278º

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.

  • Spain
    4
  • Belgium
    1
  • Czech Republic
    1
  • France
    1
  • Ireland
    1
  • Serbia
    1