Navigation Flashcards
Define Air Navigation
The art and science of efficiently directing an aircraft from one place to another and determining the aircrafts position.
Essential problem of navigation
Where are we?
Where are we going?
How will we get there?
When will we get there?
Shape of the earth?
Oblate spheroid
Shape of the earth for Nav purposes
Perfect sphere
True Poles
Extremities of the diamater about which the earth rotates
Magnetic Poles
Extremeties of the diameter indicated by a north seeking compass
Great Circle
Line on the earths surface which with a centre and radius the same as the earth
Small Circle
A line on the earth with a centre and radius not the same as the earth
Equator
A great circle which is perpendicular to the axis of rotation and equidistant of both poles.
Meridians
Semi-great circles that join the poles
Parallels of Latitude
Small circles parallel to the equator
Rhumb lines
A regularly curved line that cuts all meridians at a constant angle
Problem of representing a curved surface on a flat map
Distortion
Properties of an ideal map
Conformality
Constant scale
Equal area
Great circles are straight lines
Rhumb lines are straight lines
Adjacent maps fit together
Geographic position easily fixed
Properties of conformality
Scale expanision/contraction is independant of azimuth/direction
Shape on chart conforms with area being portrayed
Meridians and parallels cut at right angles
Mercator Projection Properties
Great circle is curved convex to pole
Scale is constant only at the standard parallel
Bearings are correct
Rhumb lines are straight
Equator and meridians are only great circles with straight lines
Mercator Limitations
Cant depict poles
Must apply conversion angle to great circle tracks
Distortion of large shapes
Large distances are difficult to measure
Limited to 70N-70S
Rhumb lines are straight
Great circles are convex
Lamberts Conformal Properties
Great circles are straight lines
Rhumb lines are curved concave to nearest pole
2 standard parallels
Constant scale
Conformal
Maps fit E-W if same parallels
What must you be careful of when plotting on a lamberts conformal projection?
Lines of longitude convergence
Methods of scale
Fraction (1:100 000)
Words (One inch to one mile)
Graphically
Major properties of aviation charts
Latitude/longitude grid
Elevation in feet
Mercator/lamberts projection
Centrally controlled
High level instrument charts
ERC (H)
ONC
Low level visual charts
ERC (L)
VNC
One grid of LAT/LONG chart
ERC (L)
