Aeronautical charts Flashcards
Projection
Method used to represent a spherical shape on a flat surface (results in some distortion of shape and size)
What increases distortion
Larger mapped areas have larger distortion
Orthomorphic
Correct shape/conformity (it has been mathematically adjusted)
If a projection is to be orthomorphic what conditions must be satisfied
- Shapes and features must be correctly placed
- Meridians and latitudes must intersect at right angles as they do on the earths surface
- Scale at any point must be independent of direction (for any part of the chart the scale is the same along both parallels and meridians, although it may vary over large distances it must be within certain limits and have a constant rate of change)
Mercator orthomorphic?
Yes
Mercator poles projected?
No
Mercator scale constant?
No (increasing away from equator)
Mercator shapes correctly represented?
Yes (areas arent)
Mercator meridians of longitude
Parallel straight lines equidistant apart
Mercator parallels of lattitude
Straight lines expanding away from the equator
Mercator adjoining sheets
If if same scale they will fit together N-S and E-W
Mercator Great circles
Curved convex to the nearest pole
Mercator rhumb lines
Straight lines
Lambert conformal orthomorphic
Yes (conformal)
Lambert conformal poles projected
Yes
Lambert conformal scale constant
Yes
Lambert conformal shapes correctly represented
Yes (areas not quite)
Lambert conformal meridians of longitude
Straight lines converging at the poles
Lambert conformal parallels of latitude
Arc’s concave to the nearest pole
Lambert conformal adjoining sheets
If using the same standard parallels they will fit E-W but not N-S
Lambert conformal great circles
Closely resemble straight lines
Lambert conformal rhumb lines
Curved lines concave to the nearest pole
Lambert conformal conical projection process of creating
Cone cuts the earths surface at 2 places called the standard parallels and then it is mathematically adjusted to make it orthomorphic
Lambert conformal advantages
- Can map polar regions, poles and high latitudes
- Can measure distances accurately
- Can plot great circles so it is good for radio wave maps
Lambert conformal parallel of origin
it is equidistant to the standard parallels
Lambert conformal uses
It is selected by the ICAO to be used for aeronautical maps for mid-high latitudes
Mercator creation process
Can be imagined as a cylinder being placed around a globe with a light source at the centre of the earth projecting the parallels and meridians onto the cylinder which can then be laid flat
Mercator uses
It gives correct representation of bearings, in aviation maps are only to be used for equatorial regions
Mercator disadvantages
- Very large distances are difficult to measure
- Cant plot great circle radio bearings
- Cant be used above 70 N or S latitude because of scale expansion
Aerodrome plates
AIP vol 4, contains
- runway dimensions, bearing, length, surface, slope, group rating
- circuit direction and height
- aerodrome elevation
- frequencies
- operational aerodrome info
- lighting
- fuel and passenger facilities
Aeronautical charts types
- VPCs (visual planning chart): used for planning, yellow chart, scale 1:1,000,000
- VNCs (visual navigation chart): used for in flight navigation, can either be blue with a scale of 1:500,000, green with a scale of 1:250,000 or orange with a scale of 1:125,000
Chart scale
The ratio of a given distance on a map to the actual earth distance it represents
Chart legend
Provides a key for airspace, geographical features and symbols
Relief
It is the variation in height and slope of the earths surface above MSL, it can be found on the chart legend depicted by colour tinting, shading, spot heights and max elevation figures
