Aeronautical Chart, Properties & Principles

Question 1

Explain difficulties associated with representing a spherical shape on a flat surface:

Answer 1

There’ll always be a degree of distortion, impossible to convert a section of a curved surface onto a flat sheet and retain total accuracy

Question 2

Describe the process of creating a Mercator projection

Answer 2

Rectangular circle surrounding the earth and al one tangential to the equator

Question 3

Describe process of a creating a lamberts conformal projection

Answer 3

Cone over the top of the earth.

Question 4

List and explain the properties of a Mercator projection. (10 things )

Answer 4

• Conformal (orthomorphic) bearings are correct
• poles are not projected
• scale isn’t constant, increases away from equator
• shapes are represented correctly
• meridians are straight line, equi-distant
• parallels of latitude are straight line, expanding from equator
• meridians parallel of latitude
• great circles are curved convex to nearest pole
• character scale at lat angle = scale@equator x 1/cos angle

Question 5

Mercator chart disadvantages

Answer 5

• Distances are difficult to measure accurately
• Great circles can’t be plotted.
  Cannot use chart at latitudes > 70ºN & 70ºS

Question 6

Lamberts conformal projection properties

Answer 6

• poles projection
• conformal by construction (bearing at right angles)
• meridians are straight lines radiating from nearest pole
• parallels of latitude are arcs concentric and evenly spaced, concave to the same pole
• GCS are straight lines, RH are curved concave
• Charts scale considered constant

Question 7

Disadvantages of Lambert’s conformal chart

Answer 7

Area between two standard parallels, theres a small degree of compression and above, small degree of expansion.

Conformal, Constant scale or constant rate of expansion, parallels of latitude or meridians of longitude intersect at 90º

Question 8

Explain the use of Mercator projection

Answer 8

Short distance travel

Question 9

Explain the use of lamberts conformal projection

Answer 9

Useful for representing latitudes above 70º latitude, distances can be measured accurate, Great circles are plotted as straight lines. Long distance travel

Question 10

Describe the use of various NZ aeronautical charts

Answer 10

VPC - 1:1,000,000 - planning chart, portray a certain amount of topographical and cultural information of NZ
VNC - 1:500,000 - detailed topographic, cultural and aeronautical information covering all airspace in NZ
VNC - 1:250,000 - green, enlarged, congested areas
Terminal chart - 1:125,000 - orange, NZCH etc

Question 11

Explain use of aerodrome charts and associated operational data pages

Answer 11

Charts contain detailed information on many NZ aerodromes. Note each type of chart needs to be orthomorphic.