Definition of Map Terms
• Map Scale = Chart Length / Earth Length
– Small Scale Big Area Less Detail
• 1:1,000,000
– Large Scale Small Area More Detail
• 1:250,000
• Great-Circle Distance: the shortest distance between two
points on the curved surface of the earth lies along the
great circle passing through these points
• Rhum Line : is a line crossing all meridians at a constant
angle.
– This is the line which an aircraft tends to follow when steered by
a compass
– It is a greater distance than the great-circle route between the
same two points
Advantages to fly a Rhumb Line
course instead of great circle
1. In low latitude, a R/L closely
approximates a great circle
2. Over short distances, a R/L and G.C.
nearly coincide
3. A R/L between points on or near the
same meridian of longitude approximates
a great circle
Definition of Map Terms
•
Conformality (correct representation of
angles) :
1. To be conformal, a chart must have uniform
scale around any points, though not
necessarily a uniform scale over the entire
map.
2. Meridians and Parallels must intersect at
right angle
Mercator and Lambert are conformal
Developed and Undeveloped
Surface
• The surface of sphere or spheroid is said
to be undevelopable because no part of it
may be spread out flat without distortion
• A plane, cylinder or cone which can be
easily flattened, is called developable
surface .
• Projection on these surface are termed
Conical, Cylindrical, and Azimuthal
Projection
Develop for flat of the earth
2.Cylinder
3.Cone
1.Plane
Azimuthal
Cylindrical
Conical
Point of Tangency
• Names of Charts are different due to point of
tangency such as a plane of projection
tangent.
• Tangent at the Equator, called Equatorial Proj
• Tangent at the Poles, called Polar Proj
• Tangent at other places, called Oblique Proj
Point of Tangency
E W
W
N
N
N
E
E W
S
S
S
Tangent at Pole
Tangent at Equator
Tangent at other point
called “POLAR”
called “EQUITORAIL”
called “OBLIQUE”
แบบการจาลองแผนที่ Projection
• The method of representing all or part of
the surface of a sphere or spheroid on a
plane surface is called a map or chart
project.
Projection
Gnomonic Proj
Stereo Proj
Orthographic Proj
(Proj from the center
of the sphere)
(Proj from the
opposite side of the
sphere)
(Proj from the
infinity)
Azimuthal Projection
1. Polar Tangency 3 names
1. Polar Azimuthal Gnomonic Proj
2. Polar Azimuthal Stergographic Proj
3. Polar Azimuthal Orthographic Proj
2. Oblique Tangency 3 names
1. Oblique Azimuthal Gnomonic Proj
2. Oblique Azimuthal Stergographic Proj
3. Oblique Azimuthal Orthographic Proj
Azimuthal Projection
3. Equitorail Tangency 3 names
1. Equitorail Azimuthal Gnomonic Proj
2. Equitorail Azimuthal Stergographic Proj
3. Equitorail Azimuthal Orthographic Proj
Common Charts Used in
Navigation
1. Map Reading
2. Plotting and Measuring Course
Directions and Distance
Ideal Chart
1. Comformality (รู ปร่ างเหมือนจริ ง)



Parallels and meridians must intersect at 90°
Scale or scale expansion must be the same
along the meridians as it is along the
parallels
Scale vary point to point but it is the same in
all direction (Scale of any point independent
from Azimuth)
Ideal Chart
2. Constant and Correct Scale
– Constant ratio to bear to distance on the earth
3. Correct Shape Representation
4. Correct Area Representation
5. Coordinate Easy to Located
6. Rhumd Lines as Straight Lines (Mercator
map)
7. True Azimuth
Cylindrical Projection (Mercator)
• The only cylindrical projection used for air NAV is the
MERCATOR
• GERHARD MERCATOR design this type of chart first in
1569
• The other types of the Mercator are Oblique Mercator
and Transverse Mercator
N
Plane Mercator
Oblique Mercator
S
Transverse Mercator
Polar Cylindrical
Gnomonic Proj
Mercator Projection
• Its graticule can be imagined by visualizing a
cylinder tangent at the equator to a translucent
globe with a light source at the center.
• All parallels and meridians on the globe will be
projected on the cylinder as straight lines crossing
at right angles
• Meridians will be evenly spaced, whereas
distance between parallels will increase rapidly
with latitude.
• Scale on a Mercator is true only along the equator.
Elsewhere it expands as the secant of the latitude,
so that at 60°N or S , scale is twice that at the
equator.
• Best suited for use Mercator Projection is
within 25 - 30° of the equator
• In low latitudes, rhumb line and great circle
will be close together; at middle and upper
latitudes the amount of divergence becomes
quite marked.
• The great-circle route will always be shorter,
and it is part of the navigator’s duty to
determine whether the bother of plotting and
the increased risk of error in flying a series
of changing heading is justified by the
saving in distance.
Characteristic of Mercator
1.
Conformality

2.
The meridians and parallel appear as straight lines, intersected
together at right angle
Area

3.
The area is not equal and are Greatly exaggerated in height Lat.
Scale

Scale correct only at the equator else where it expand as the
secant of Lat .
Using mid-lat scale to measure distance

4.
5.
Great Circle appear as curve line convex to the nearest
pole
RHUM Line appear as a straight lines (The meridian
parallel together)
1.
Rhum Line is the lines the success that cross the successive
meridian at the same angle
• Rhumb Line
– Between 2 points, the shortest distance is the
great circle
– Fly by Rhum Line Track, the pilot must not
change HDG all the time
The Advantage of Mercator
1. Position in Lat and Long are easy to plot
2. Easy to fly follow R/L track
The Disadvantage of Mercator
1. Difficulty of measuring large distance
accurately
2. Conversion angle (C.A) must be applied
to Great Circle bearing before plotting
3. The chart is useless in polar region
above 80°N or S since the polar cannot
be shown conversion angle
Conversion Angle
• The meridians converge towards the poles . A
Great Circle (GC) gives shortest distance
between 2 positions while R/L running between
the same position cut meridian at the same
angle.
• It is spiral curve and therefore represent a longer
distance that means that there will be a
difference between the R/L angle which the GC
angle at the start point and the ending point of
the track
Conversion Angle
•
•
Conversion Angle (CA) is the angular
difference between a great circle bearing and
a R/L bearing
Or angle between a great circle are joining
two places on earth and a R/L between the
two places
• CA = (C’(CH) Long /2)× sin mean Lat
• Difference of Long (D’ Long) is the angular
difference between two longitude angle from
0 Long to 180º E and 180º W Long such as :
from A to B D’Long = 150-15 =135 W
Pri-meridian
Greenwich
Meridian
NP
15ºW
D’Long 135ºW
150ºW
Anti-meridian
• Change of Long (CH.Long) is the angular
difference between two Longitude angles (In
case of crossing prime-meridian or antimeridian
– From A to C CH.Long = 15W + 60E = 75E
– From C to B CH.Long = 120E + 30W = 150W
CH.Long
(180-60)+(180-150)
75ºE
A 15ºW
C 60ºE
Note: Same Direction (-)
East
West
CH.Long
150ºW
B 150ºW
Difference Direction (+)
• Difference of Lat (D’Lat) is the angular
difference between two Lat. Angle . For
instance, the north pole and the equator
have a D’Lat of 90º from the north pole to
the equator the D’Lat is 90ºS. If from the
south pole to equator , D’Lat is 90º N
• From 20ºN to 40ºN D’Lat = 20ºN
• 1º = 60 NM yield 20ºN = 20×60 = 1200 NM
40ºN
20ºN
0º
• Change of Lat (CH.Lat) is the angular
different between two Lat angle (in case of
crossing equator) such as from 30ºN to 30ºS
CH.Lat is 60ºS. if from 30ºS to 30ºN CH.Lat
60ºN
CH.Lat
60ºN
30ºN
0º
30ºS
CH.Lat
60ºS
• Example, When the A/C is in position Lat35°15’S
Long 10°45’E and ground station is Lat 25°45’S
Long 02°15’W what is conversion angle value?
Solve
CA=D’(CH) Long /2 × sin mean Lat
CH Long = 10°45’E + 02°15’W
= 13°
Mean Lat = (35°15’S + 25°45’S) / 2
= 61°/2 = 30°30’ = 31°
CA. = (13 /2) × sin 31
= 3°
Conic Projection
•
•
•
The Conic Projection bases on cone
tangent reduce earth every place
The great majority of aeronautical chart
in use today are based on conic
projection
There are 2 classes of conic proj.
1. Simple Conic Proj with one Standard
Parallel (S.P.) a lot of error
2. Conic Proj with 2 S.P. And expand out of
S.P.
Lambert Conformal Conic
Projection
• In a simple conic project the cone is held
tangent to the globe along a line of latitude
called the “standard parallel”.
• Scale is exact everywhere along this standard
parallel, but increase rapidly above and below
• Lambert visualized the cone as making a
secant cut, thus giving two standard parallels
• Scale along both is exact. Between them,
scale is too small, beyond them too large.
• For equal distribution of scale error,
standard parallels are chosen at one-sixth
and five-sixths of the total spread of latitude
to be represented.
– To map the U.S, whose lat is from 25° to 49 °,
standard parallels of 29 ° and 45 ° (one-sixth
and five-sixths of the total spread ) would
produce an equal distribution of scale error.
Conic Projection
Simple Conic Proj
with one Standard
Parallel (S.P.)
Lambert Conic
Proj with two
Standard Parallel
(S.P.)
101%
100%
98%
100%
The Lambert
• All meridians are straight lines that meet in a common point
beyond limits of the map
• Parallels are concentric circles whose center is at the point
of intersection of the meridians
• Meridians and parallels intersect at right angles
• Since scale is very nearly uniform around any point on a
given chart, it is considered a conformal projection
• For map reading and radio navigation the projection is
unequaled , and most areas of the world through 80
latitude are covered by aeronautical charts with scale of
1:500,000 and 1:1,000,000
• Above 80 , scale on a standard Lambert is too inaccurate
for navigational use.
Characteristic of The Lambert
1. Conformal
2. Scale correct on S.P. contracted inside and
expand outside
3. Area – not an equal area
4. Shape – distortion small
5. GC. – curves concave to parallel of origin
considered as straight line
6. Rhumb Line curves concave to nearer pole
7. Graticule – meridians straight line ,
- parallel concentric circle
Polar Stereographic Projection
• A flat surface is used, touching the N.P.
• The light is at the S.P.
• The polar sterographic is modified by using a
secant plane instead of tangent plane
• A secant เส้นตรงที่ลากตัดส่ วนโค้ง
NP
90°N
SP
• Modified polar stereographic proj. used
secant plane as plane of tangency
(Graticule)
• The meridians are straight lines, radiating
from the pole.
• The parallels are concentric circles expands
away from the pole
180
270
NP
0
Polar Sterographic Graticule
Greenwich Meridian
090
Characteristic of Stereographic
1.
2.
3.
4.
5.
Conformal
Correct at pole tangency
Shapes: distorted away from pole
Area: distorted away from pole
GC. Curve concave to pole to 90° N,
considered as straight line about 70°N
6. Polar Stereographic used only 80°N near
north and south pole
Map Reading
• Determination of the aircraft position by
matching natural or built-up features with
their corresponding symbol on a chart
• Parallels and Meridians Prime Meridian is 0 reference for Lat
Pass Greenwich
Parallel of Latitude
Equator is 0 reference for Lat
Longitude
Meridian
• Latitude and Longitude
– Latitude range from 0° at the equator to 90°N
and 90°S at the pole
– Longitude is measured around the earth both
eastward and west ward from Prime meridian,
through 180°
• Geographic Coordinate System
– Read intersection of Latitude and Longitude
– Lat first then Long
– U-Tapao : Lat 12°40’N Long 101°04’E
•
Grid System
1. GEOREF System (GEO GRAPHIC REFENCE
SYSTEM)
Consist of 4 letters and 4 numbers
1. Divided meridian 360° / 15° = 24 spaces
– Each 24 has letter run from A to Z except I and O, start from
south pole 90°S and Long 180°
– Divided Latitude 180° / 15° = 12 spaces
– Each 12 space has letter run from A to M except I
– Total 288 spaces (15°× 15 º) per each
2. Each sqr (15°× 15 º) divided by 15º = 1º
– Define letter A to Q except I and O
– Total 225 spaces (1°× 1 º) per each
3. Each 1º divided by 60 = second
Reading: Right – Up or Long - Lat
M N
P Q R S
T
U V W X
Y
Z
A
B
C D E
F G H
J
K
L
M N
P Q R S
T
U V W X
Y
Z
A
B
C D E
F G H
J
K
L
L
K
J
H
G
F
E
D
C
B
A
UG
Q
P
O
N
M
L
K
J
H
G
F
E
D
C
B
A
B
C
D
E
F
G
UGEK3010
H
J
K
L
M
N
P
Q
Aeronautical Chart
1. Charts for Visual Flight Rules (VFR)



World Aeronautical Charts (WAC)
1:1,000,000
Sectional Charts 1:500,000
VFR Terminal Area Charts 1:250,000
2. Charts for Instrument Flight Rules (VFR)



Enroute Chart
Standard Instrument Departure (SID)
Standard Terminal Arrival (STAR)
World Aeronautical Chart (WAC)
• WACs are used for plotting and pilotage
• WAC is published by the US.Coast and
Geodetic Survey
• Scale is 1:1,000,000 They are based on
– Lambert conformal project 0° to 80°N and
80°S
– Modified Polar Stereographic Project from
80°N and 80°S to the pole
สั ญลักษณ์ บนแผนที่
1. แสดงรายการของภูมิประเทศ (Topographical
Symbols)
2. แสดงรายการเกี่ยวกับการบิน (Aeronautical Symbols)
1. แสดงรายการของภูมิประเทศ
(Topographical Symbols)
• แสดงรายการความสูงของพื้นที่ มี ๔ วิธี
1. เส้นลายขอบเขา (Contour Lines)



ทุกๆจุดบนเส้นลายขอบเขามีความสู งจากระดับน้ าทะเลเท่ากัน
เส้นชั้นความสู งอยูช่ ิดกัน แสดงว่าบริ เวณนั้นสู งชัน
เส้นชั้นความสู งอยูห่ ่างกัน แสดงว่าบริ เวณนั้นเป็ นที่ราบสู ง
2. ด้วยสี (Gradients Tints)



S.L. – 1,000 ft : dark green
1,000 – 2,000 ft: weak green
2,000 – 10,000 ft : brown to dark brown
3. ด้วยตัวเลข (Spot Elevation)
– แสดงระยะสู งที่แน่นอนด้วยตัวเลข จากระดับน้ าทะเล
4. ด้วยลายเส้นและแลเงา (Hachure or Shading)
– ลายลึก หรื อแลเงาหนาทึบ แสดงว่า ลาดชันมาก
5. แสดงรายการของพื้นน้ า (Drainage or Hydrography)
– Blue
6. แสดงสิ่ งก่อสร้างที่มนุษย์สร้างขึ้น (Cultural Features)
– Chart Legend
7. แสดงบริ เวณป่ าและพืชผล (Vegetation)