The document defines several types of directions used for navigation including: True direction which references the geographic North Pole, magnetic direction which references the magnetic North Pole, compass direction which can differ from magnetic due to interference, grid direction which references grid lines on a chart, and relative direction which is measured from the aircraft's axis. It also defines concepts like variation which is the difference between true and magnetic direction, deviation which is the difference between magnetic and compass direction, and convergence which is the difference between grid and true direction.

2. Where is the North?
What North is that one?
How are you going to make it there?
But the good question is…..
Do you really know where you are going?

3. Horizontal Plane > Direction
Vertical Plane > Inclination, slope, elevation

4. Definitions:
Course: Intendend track
Heading: Directions in which the fore-
and-aft axis of the aircraft is pointing
Track: Flight path that the aircraft has
followed (Track Made Good)

5. TRUE DIRECTION: Any direction in reference to the
directions of the Geographic North Pole (True
North = TN)

6. MAGNETIC DIRECTION
MAGNETIC FIELD:
- 2 Magnetic Poles not co-located with the
Geographic (Not antipodal)
- “Meridians” & “Parallels”. Not
homogeneous! (Areas of magnetic
disturbance)

9. MAGNETIC DIRECTION:
MAGNETIC FIELD:
- ANGLE OF DIP: Angle crated between the
horizontal (Parallel to the earths
surface) and vertical (Perpendicular
to the Earths surface) components of
the magnetic field. Isoclinal / Aclinic
lines
Horizontal component = Magnetic
direction

12. MAGNETIC DIRECTION: Any direction in reference
to the direction of the Magnetic North Pole
(Magnetic North Pole = MN)

14. COMPASS DIRECTION: Any direction in reference
to the Compass North (Compas North Pole = CN)
Due to the fact of the compass being
imperfect and to the possible
electromagnetic fields induced on the
needle, the compass will not indicate the
real magnetic north > COMPASS NORTH

16. GRID DIRECTION: Any direction in reference to the
Grid North (GN).
The Grid North is associated with the Grid
Reference Meridian (Grid Datum Meridian).
GRID: Parallel lines, printed on a chart, that are
parallel to the Grid Reference Meridian.(Widely
used on Polar Stereographic charts

18. RELATIVE DIRECTION: Any direction, measured
angularly, in reference to the aircraft’s
longitudinal axis

19. TRUE BEARING = TRUE HEADING + RELATIVE BEARING
TB = TH + RB

20. Heading H TH = True Heading
Track T MT = Magnetic Track
Bearing B RB = Relative Bearing
Course C GC = Grid Course
Course means intended track. But , when
crourse is used, track is only used to refer the
path already flown
If not specifying a particular type of line:
DIRECTION (TD, MD, GD)

21. DEFINITION: Relationship between a direction given in
term of True and terms of Magnetic
Relationship between the direction of the
Geographical Meridian and the Magnetic Meridian
through the same place. Isogonal/Agonic lines
EASTERLY : If MN seems to lie to the east of
the TN
WESTERLY: If MN seems to lie to the west of
the TN

22. MH = TH + VarE MH = TH - VarE

23. Variation WEST, Magnetic BEST
Variation EAST, Magnetic LEAST

24. DEFINITION: Relationship between a direction given
in relation to the MN and the same given in
relation to the CN.
Relationship between the direction of the Magnetic
North and the one to which the compass points for
any given position on the Earth.
Measured in degree from the Magnetic North MN

26. DEVIATION WEST - COMPASS BEST
DEVIATION EAST - COMPASS LEAST

27. DEFINITION: Defined for a position, is the
angular difference between the direction
towards the Grid North and the Meridian in
that position.
Angular difference between GN and TN on
a particular position.
East: TN lies to the east of GN
West: TN lies to the west of GN

29. DEFINITION: In a position, is the angular
difference between the Grid North and the
Magnetic North in that position.
Includes both, Grid Convergence and
Magnetic Variation (GRIV)
ISOGRIVES: Lines joining positions with the
same grivation