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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 twopoints on the curved surface of the earth lies along thegreat circle passing through these points

Rhum Line : is a line crossing all meridians at a constantangle. 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

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Advantages to fly a Rhumb Linecourse instead of great circle

1. In low latitude, a R/L closelyapproximates a great circle

2. Over short distances, a R/L and G.C.nearly coincide

3. A R/L between points on or near thesame meridian of longitude approximatesa great circle

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Definition of Map Terms

Conformality (correct representation of angles) :

1. To be conformal, a chart must have uniformscale around any points, though notnecessarily a uniform scale over the entiremap.

2. Meridians and Parallels must intersect atright angleMercator and Lambert are conformal

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Developed and UndevelopedSurface

The surface of sphere or spheroid is saidto be undevelopable because no part of itmay be spread out flat without distortion

A plane, cylinder or cone which can beeasily flattened, is called developablesurface .

Projection on these surface are termedConical, Cylindrical, and AzimuthalProjection

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1.Plane 2.Cylinder 3.Cone

Azimuthal Cylindrical Conical

Develop for flat of the earth

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Point of Tangency

Names of Charts are different due to point of tangency such as a plane of projectiontangent.

Tangent at the Equator , called Equatorial Proj Tangent at the Poles , called Polar Proj

Tangent at other places , called Oblique Proj

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Point of Tangency

N N N

W W W

S S S

E E E

Tangent at Pole

called POLAR Tangent at Equator

called EQUITORAIL Tangent at other point

called OBLIQUE

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Projection

The method of representing all or part of the surface of a sphere or spheroid on aplane surface is called a map or chartproject.

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Gnomonic Proj

(Proj from the center of the sphere)

Stereo Proj

(Proj from theopposite side of the

sphere)

Orthographic Proj

(Proj from theinfinity)

Projection

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Azimuthal Projection

1. Polar Tangency 3 names1. Polar Azimuthal Gnomonic Proj2. Polar Azimuthal Stergographic Proj3. Polar Azimuthal Orthographic Proj

2. Oblique Tangency 3 names1. Oblique Azimuthal Gnomonic Proj2. Oblique Azimuthal Stergographic Proj3. Oblique Azimuthal Orthographic Proj

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Azimuthal Projection

3. Equitorail Tangency 3 names1. Equitorail Azimuthal Gnomonic Proj2. Equitorail Azimuthal Stergographic Proj3. Equitorail Azimuthal Orthographic Proj

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Common Charts Used inNavigation

1. Map Reading2. Plotting and Measuring Course

Directions and Distance

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Ideal Chart

1. Comformality ( ) Parallels and meridians must intersect at 90 Scale or scale expansion must be the samealong the meridians as it is along theparallelsScale vary point to point but it is the same in

all direction (Scale of any point independentfrom Azimuth)

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Ideal Chart

2. Constant and Correct Scale Constant ratio to bear to distance on the earth

3. Correct Shape Representation

4. Correct Area Representation5. Coordinate Easy to Located

6. Rhumd Lines as Straight Lines (Mercator map)

7. True Azimuth

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Cylindrical Projection (Mercator)

The only cylindrical projection used for air NAV is theMERCATOR

GERHARD MERCATOR design this type of chart first in1569

The other types of the Mercator are Oblique Mercator and Transverse Mercator

Plane Mercator Oblique Mercator

Transverse Mercator Polar CylindricalGnomonic Proj

N

S

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Mercator Projection Its graticule can be imagined by visualizing a

cylinder tangent at the equator to a translucentglobe with a light source at the center.

All parallels and meridians on the globe will beprojected on the cylinder as straight lines crossingat right angles

Meridians will be evenly spaced, whereasdistance between parallels will increase rapidlywith 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 theequator.

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Best suited for use Mercator Projection iswithin 25 - 30 of the equator

In low latitudes, rhumb line and great circlewill be close together; at middle and upper latitudes the amount of divergence becomesquite marked.

The great-circle route will always be shorter,and it is part of the navigators duty todetermine whether the bother of plotting and

the increased risk of error in flying a seriesof changing heading is justified by thesaving in distance.

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Characteristic of Mercator

1. ConformalityThe meridians and parallel appear as straight lines, intersectedtogether at right angle

2. AreaThe area is not equal and are Greatly exaggerated in height Lat.

3. ScaleScale correct only at the equator else where it expand as thesecant of Lat .Using mid-lat scale to measure distance

4. Great Circle appear as curve line convex to the nearestpole

5. RHUM Line appear as a straight lines (The meridianparallel together)

1. Rhum Line is the lines the success that cross the successive

meridian at the same angle

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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

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The Advantage of Mercator

1. Position in Lat and Long are easy to plot2. Easy to fly follow R/L track

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The Disadvantage of Mercator

1. Difficulty of measuring large distanceaccurately

2. Conversion angle (C.A) must be appliedto Great Circle bearing before plotting

3. The chart is useless in polar regionabove 80 N or S since the polar cannotbe shown conversion angle

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Conversion Angle

The meridians converge towards the poles . AGreat Circle (GC) gives shortest distancebetween 2 positions while R/L running between

the same position cut meridian at the sameangle. It is spiral curve and therefore represent a longer

distance that means that there will be adifference between the R/L angle which the GCangle at the start point and the ending point of the track

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Conversion Angle

Conversion Angle (CA) is the angular difference between a great circle bearing anda R/L bearing

Or angle between a great circle are joiningtwo places on earth and a R/L between thetwo places

CA = (C(CH) Long /2) sin mean Lat

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Difference of Long (D Long) is the angular difference between two longitude angle from

0 Long to 180 E and 180 W Long such as :from A to B DLong = 150 -15 =135 W

NP DLong 135 W

15W

150W

Pri-meridian

GreenwichMeridian

Anti-meridian

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Change of Long (CH.Long) is the angular difference between two Longitude angles (Incase of crossing prime-meridian or anti-meridian From A to C CH.Long = 15W + 60E = 75E

From C to B CH.Long = 120E + 30W = 150W(180-60)+(180-150)

B 150W

A 15W C 60E

East West

CH.Long150W

CH.Long75E

Note: Same Direction (-)

Difference Direction (+)

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Difference of Lat (DLat) is the angular difference between two Lat. Angle . For instance, the north pole and the equator have a DLat of 90 from the north pole tothe equator the DLat is 90S. If from the

south pole to equator , DLat is 90 N From 20N to 40 N DLat = 20N 1 = 60 NM yield 20N = 20 60 = 1200 NM

40N

20N0

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Change of Lat (CH.Lat) is the angular different between two Lat angle (in case of crossing equator) such as from 30N to 30SCH.Lat is 60S. if from 30S to 30N CH.Lat60N

0

30S

30N

CH.Lat60N

CH.Lat60S

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Example, When the A/C is in position Lat35 15 SLong 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

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Conic Projection

The Conic Projection bases on conetangent reduce earth every place

The great majority of aeronautical chartin use today are based on conicprojection

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.

b f l

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Lambert Conformal ConicProjection

In a simple conic project the cone is heldtangent to the globe along a line of latitudecalled the standard parallel .

Scale is exact everywhere along this standardparallel, 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.

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For equal distribution of scale error,standard parallels are chosen at one-sixthand five-sixths of the total spread of latitudeto be represented. To map the U.S, whose lat is from 25 to 49 ,

standard parallels of 29 and 45 (one-sixthand five-sixths of the total spread ) wouldproduce an equal distribution of scale error.

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Conic Projection

Simple Conic Projwith one StandardParallel (S.P.)

Lambert ConicProj with twoStandard Parallel(S.P.)

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101%

100%

98%

100%

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The Lambert

All meridians are straight lines that meet in a common pointbeyond 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.

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Characteristic of The Lambert

1. Conformal2. Scale correct on S.P. contracted inside and

expand outside3. Area not an equal area4. Shape distortion small5. GC. curves concave to parallel of origin

considered as straight line6. Rhumb Line curves concave to nearer pole7. Graticule meridians straight line ,

- parallel concentric circle

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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

NP

SP

90 N

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Modified polar stereographic proj. usedsecant plane as plane of tangency

(Graticule) The meridians are straight lines, radiatingfrom the pole.

The parallels are concentric circles expandsaway from the pole

NP

180

0

270 090

Polar Sterographic Graticule Greenwich Meridian

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Characteristic of Stereographic

1. Conformal2. Correct at pole tangency3. Shapes: distorted away from pole4. Area: distorted away from pole5. GC. Curve concave to pole to 90 N,

considered as straight line about 70 N6. Polar Stereographic used only 80 N near

north and south pole

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Map Reading

Determination of the aircraft position bymatching natural or built-up features withtheir corresponding symbol on a chart

Parallels and Meridians

Equator is 0 reference for Lat

Prime Meridian is 0 reference for Lat

Pass Greenwich

Parallel of Latitude

Longitude

Meridian

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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 40N Long 10104E

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Grid System1. GEOREF System (GEO GRAPHIC REFENCE

SYSTEM)Consist of 4 letters and 4 numbers1. Divided meridian 360 / 15 = 24 spaces

Each 24 has letter run from A to Z except I and O, start fromsouth 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 ) per each2. Each sqr (15 15 ) divided by 15 = 1

Define letter A to Q except I and O

Total 225 spaces (1 1 ) per each3. Each 1 divided by 60 = second

Reading: Right Up or Long - Lat

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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

M N P Q R S T U V W X Y Z A B C D E F G H J K L

UG

Q

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P

O

N

M L

K

J

H G

F

E

D C

B

A B C D E F G H J K L M N P Q

UGEK3010

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Aeronautical Chart

1. Charts for Visual Flight Rules (VFR)World Aeronautical Charts (WAC)1:1,000,000

Sectional Charts 1:500,000VFR Terminal Area Charts 1:250,000

2. Charts for Instrument Flight Rules (VFR)Enroute ChartStandard Instrument Departure (SID)Standard Terminal Arrival (STAR)

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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 and80 S

Modified Polar Stereographic Project from80 N and 80 S to the pole

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1. (TopographicalSymbols)

2. (Aeronautical Symbols)

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. (Topographical Symbols)

1. (Contour Lines)

2. (Gradients Tints)

S.L. 1,000 ft : dark green1,000 2,000 ft: weak green2,000 10,000 ft : brown to dark brown

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3. (Spot Elevation)

4. (Hachure or Shading)

5. (Drainage or Hydrography) Blue

6. (Cultural Features) Chart Legend

7. (Vegetation)