Nav 03 Flashcards
Direction
Position of one point in space relative to another, without reference to the distance between them
Angle that a live makes w/ some reference datum line passing through the point
Always measured clockwise from the datum
Always expressed in a three figure group
Quadrant points
NE, NW, SE, SW
Sexagesimal
Base of 60, used for time and direction
East
Direction in which the earth is spinning
West
Direction opposite to East
North
Direction of the North Pole
South
Direction opposite to North
True direction
Direction measured w/ reference to the direction of the geographic North Pole
Magnetic direction
Direction measured w/ reference to the direction of mag North at the place
Magnetic force
2 regions on the surface of a magnet where its attractive force is the greatest
Attractive force is treated as if it emanates from 2 internal points called poles
Poles are the position of the greatest field intensity
Magnetic Meridian
Direction of the horizontal component of the earth’s magnetic field at a point
Secular change
Average value changes in the earth’s magnetic field over time, reflecting changes in the earth’s core = unpredictable
Local anomaly
Anomaly caused by metal on earth or man made materials
Annual variation
Average monthly values of the magnetic elements are corrected for secular change
Magnetic storms
Solar flares cause irregularities in the earth’s magnetic field
Soft iron magnetism
Caused by the magnetism induced into soft material. Consists of magnetic fields induced solely by the earth’s magnetic field
Varies w/ changes in heading and magnetic latitude
Isogonal
Line on a map joining points of equal variation
Not coincident w/ the magnetic meridian and therefore does not indicate the direction of the earth’s field at a point
Agonic line
Line on a map joining points of zero variation
Variation
Horizontal angle between true north and magnetic north
West is best, East is least
Hard iron magnetism
Caused by the permanent magnetism (metal structures) and DC circuits of the a/c
Remains constant w/ changes to heading and magnetic latitude
Deviation
Angular difference between compass north and magnetic worth
West is best, East is least
