3.Directions

DIRECTIONS

QUESTIONS TO THINK ABOUT:

How are you going to make it there?

But the good question is…..

Do you really know where you are going?

Where is the North?

What North is that one?

DIRECTIONAL DATUMS & MEASUREMENTS

Horizontal Plane > Direction

Vertical Plane > Inclination, slope, elevation


Definitions:

Course: Intendend track

Heading: Directions in which the fore-and-aft axis of the aircraft is pointingTrack: Flight path that the aircraft has followed (Track Made Good)


TRUE DIRECTION: Any direction in reference to the directions of the Geographic North Pole (True

North = TN)


MAGNETIC DIRECTION

MAGNETIC FIELD:- 2 Magnetic Poles not co-located with the

Geographic (Not antipodal)

- “Meridians” & “Parallels”. Not homogeneous! (Areas of magnetic disturbance)




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




MAGNETIC DIRECTION: Any direction in reference to the direction of the Magnetic North Pole

(Magnetic North Pole = MN)



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



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



RELATIVE DIRECTION: Any direction, measured angularly, in reference to the aircraft’s

longitudinal axis


TRUE BEARING = TRUE HEADING + RELATIVE BEARING

TB = TH + RB

TYPE OF LINESHeading

Track

Bearing

Course

HTBC

TH = True HeadingMT = Magnetic TrackRB = Relative BearingGC = 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)

VARIATIONDEFINITION: 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

VARIATION

MH = TH + VarE MH = TH - VarE

VARIATION

Variation WEST, Magnetic BEST

Variation EAST, Magnetic LEAST

DEVIATIONDEFINITION: 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

DEVIATION

DEVIATION

DEVIATION WEST - COMPASS BEST

DEVIATION EAST - COMPASS LEAST

GRID CONVERGENCEDEFINITION: 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

GRID CONVERGENCE

GRIVATIONDEFINITION: 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

3.Directions

Technology

grid direction

compass direction

magnetic north mn

true direction

relative direction

direction td

magnetic poles

magnetic meridianthrough