Air
Navigation
Air Navigation
• การนาเครื่องบินไปถึงจุดหมายปลายทาง
• ตามเวลาทีก่ าหนด
• ด้ วยความปลอดภัย
Word Navigation
• Two Latin words:
– NAVIS: ship
– AGERE: to direct or move
Dimensions of Navigation
•
•
•
•
Position
Direction
Distance
Time
Position
• The place where the aircraft stay with
respect to the reference point
– 25 NM Radian 360 degree from U-Tapao
airport
– Lat 12 °59.0’N Long 102°59.3’E
Direction
• Angular Distance between one point and
reference point , measures clockwise start
from reference point as 0°to 360°
– HDG 180°= angular distance 180° from
magnetic north
• True Direction (TD)
• Magnetic Direction (MD)
• Compass Direction (CD)
Direction use in Air Navigation
• Track (TR) is the actual horizontal
direction made by the aircraft over the
earth (due to wind) or actual path
• Course (C) is the intend horizontal
direction or travel. There are TC, MC, CC
(Gyro Compass Course) = Track Made
Good
• Heading (HDG) is the horizontal direction
in which the A/C is pointed. There are TH,
MH, CH
Direction use in Air Navigation
• Bearing: The direction of an object from an
airplane is called the bearing of the object.
• Bearing are angular measurements from
0° through 360°
– True Bearing is measured clockwise from true
north
– Relative Bearing is measured clockwise from
the heading of the airplane
• TH + RB = TB
Direction use in Air Navigation
•
The North Datum Line
– 3 kinds of North used as reference lines for
measuring direction
1. True North (TH) any meridian of long point to
TN
TN
y
50
True direction = 050°
measure clockwise
• The North Datum Line
2. Magnetic North (MN) is measured the north
magnetic poles from the observer point
TN
MN
y
050°
045°
Magnetic Direction 045°
VAR=5°E
True Direction 050°
• The North Datum Line
3. Compass North (CN) : Electricity and magnetic
field deviate the compass to CN
TN MN
CN
y
040°
Compass Direction 040°
VAR=5°E
Magnetic Direction 045°
DEV=5°E
True Direction 050°
• VARIATION (VAR)
– The difference in angular measurement
between true north and magnetic north, use true
north as reference line
– Expressed as an angle east or west of true
north
– When the compass needle points east of true
north, the variation is said to be East
– When the compass needle points west of true
north, the variation is said to be West
– Isogonic Line: the line that equal VAR
– Agonic Line: the line that VAR equal to zero
Agonic Line
คือ เส้นที่ลากผ่านตาบลที่มี VAR เป็ น 0
Isogonic Line คือ เส้นที่ลากผ่านตาบลที่มี VAR เท่ากัน
• Deviation (DEV)
– The angle between MN and CN use MN as reference
line
– East of MN, it is deviation east
– West of MN, it is deviation west
•
•
•
•
VAR WEST Magnetic Best +
VAR EAST Magnetic Lest –
DEV WEST Magnetic Best +
DEV EAST Magnetic Lest –
Direction
• Cardinal Point (N, S, E, W) and
intercardinal point (NE, SE, SW, NW)
• Numerical system divided the horizon in to
360° starting with 000° (N) clockwise to
090°(E) , 180°(S) and 270°(W) and back to
N
• The circle of direction called Compass
Rose
Using Variation and Deviation
C
Compass
Direction
D
Deviation
357
1E
093
2E
M
V
Variation
T
True
Direction
358
2E
360
จะต้องถือMCเท่าใดจึง
จะทาให้ T เป็ น360
Error 2°east
095
5W
090
3E
185
10 E
105
Magnetic
Direction
1W
090
5E
270
2W
095
D
M
C
V
T
Compass Deviation Magnetic Variation
True
Direction
Direction
Direction
179
2W
173
13 E
186
152
2W
150
10 E
160
1W
11 E
340
2E
10 E
5E
5E
2W
4W
150
220
050
Dimensions of Navigation
• Deviation = มุมทีต่ ่ างกันระหว่ าง Magnetic North กับ
Compass North ซึ่งจะเปลีย่ นแปลงไปตามทิศหัว บ. และจะ
เปลีย่ นไปตามสถานที่
• Compass Swing
• DEV East, Compass Least
• DEV West, Compass Best
• Magnetic heading = 095º DEV 5º E Find Compass heading ?
• DEV East, Compass Least
• Compass heading = 090º
A pilot maintain compass heading of 270O , but the
deviation in aircraft compass card correction is 5O E,
and the magnetic variation around here is 8OW.
What is the true heading?
OK
a.
273O
b.
267O
c.
283 O
d.
276 O
Distance (Air Navigation)
• A partial separation between two points
and measured by the length of line joining
them
•
•
•
•
1 NM = 1 ลิปดาของ Great circle = 6,080.20 ฟุต
1 SM = 1.6 KM
1 NM = 1.85 KM
1 SM = 0.87 KM
Time
• The time of the day
– Zulu time
– Local time
• An elapsed interval
Dimensions of Navigation
•
•
•
•
Longitude/The Equator
Meridians/Anti-Meridians
Prime Meridian
Time
Local Time = UTC +E
-W Local Conversion Factor
การหา Local Conversion Factor = 1+2+3
1. Longitude(องศา)/15
= ชั่วโมง ( ไม่ คดิ เศษ)
2. นาเศษขององศามาคูณด้ วย 4
= นาที
3. นาค่ าลิปดามาคูณ 4 หารด้ วย 60 = นาที
เช่ น GMT 0200 hrs, 30 June, local longitude 68 degrees 21 minutes E.
1. 68/15 = 4 เศษ 8 = 4 ชั่วโมง
2. 8*4
= 32 นาที
3. 21*4/60 = 1.4 นาที หรือ 1 นาที 24 วินาที
Local Conversion Factor = 1+2+3 = 4 ชั่วโมง 33 นาที 24 วินาที
Local Time = UTC +E
-W Local Conversion Factor
= 02:00 +04:33:24
= 06:33:24
Local time 2000 hrs, 15 February, local long 137
degrees 15 minutes W.
What is UTC ( Conversion factor is +9)
a.
1100 hrs, 15 February.
b.
1100 hrs, 16 February.
c.
0500 hrs, 15 February.
OK d.
0500 hrs, 16 February.
UTC = Local Time + Conversion Factor
= 2000+9 =2900 = 2400 + 0500
= + 1 วัน เวลา 0500
Twilight.
คือ แสงเงินแสงทองที่เกิดขึ้นก่อนดวงอาทิตย์ข้ ึนและหลังดวงอาทิตย์ตก
แบ่งออกเป็ น 3 ช่วง
6O
Civil Twilight.
เริ่ มต้นหรื อสิ้ นสุ ดลงเมื่อศูนย์กลางของดวงอาทิตย์อยูต่ ่ากว่าขอบฟ้ า 6O
12O
Nautical Twilight.
เริ่ มต้นหรื อสิ้ นสุ ดลงเมื่อศูนย์กลางของดวงอาทิตย์อยูต่ ่ากว่าขอบฟ้ า 12O
18O
Astronomical Twilight.
เริ่ มต้นหรื อสิ้ นสุ ดลงเมื่อศูนย์กลางของดวงอาทิตย์อยูต่ ่ากว่าขอบฟ้ า 18O
10O
Observational Twilight.
เริ่ มต้นหรื อสิ้ นสุ ดลงเมื่อศูนย์กลางของดวงอาทิตย์อยูต่ ่ากว่าขอบฟ้ า 10O
Sunrise = ขอบบนของดวงอาทิตย์สมั ผัสกับขอบฟ้ า
Sunset = ขอบล่างของดวงอาทิตย์สมั ผัสกับขอบฟ้ า
Unit of Speed
• Rate of change of the position of the
object
• Speed = Distance / Time
• Ft/sec
• Mph
• Knot (NM/hr)
• Km/hr
Type of Navigation
• Dead reckoning navigation
• Piloting navigation or Map Reading
• Radio and radar navigation or electronic
navigation
• Celestial navigation or astro navigation
Dead Reckoning (DR)
• Determine where the aircraft should be or will
be, based on the wind applied to its true heading
and true airspeed from the last known position.
• PDDT
• P – Position or coordinate (Lat, Long)
• D – Direction (Truth North)
• D – Distance (NM)
• T – Time
Piloting Navigation or Map Reading
• The identification of landmarks from their
representation on a chart and the
utilization of this information to fix the
position of the aircraft or to establish lines
of position.
• Checking Dead Reckoning
• Cannot be used when the ground is
obscured by clouds or when flying over
water
Radio and Radar Navigation or Electronic
Navigation
• Determine the aircraft position by
intersecting of position line which radiated
by the radio compass
• VOR, ADF/NDB, TACAN, LORAN
Celestial Navigation
• Stars move in relation to each other, but
slowly that today almost the same in
ancient Greece
• Main propose is to provide a means of
positioning the aircraft and checking the
aircraft heading
• Required for celestial LOP (Almanac and
Sight Reduction Table)
THE EARTH’S SURFACE
• The primary instrument in navigation is a map of
the earth’s surface
The Shape of the Earth
• Earth’s size and shape: Oblate Spheroid
• For air navigation : Perfect Sphere
• Earth Rotation as Spinning Ball
• Axis of rotation as axis of the earth
• The ends of the axis of the earth are pole, North
pole and South pole
• Midway between them lies the great circle is the
equator
• Polar Diameter = 6,864.57 nm
• Equatorial Diameter = 6,887.91 nm The
difference between Polar Diameter and
Equatorial Diameter is 23.34 nm
• Ellipticity (Ratio) = 23.34 / 6887.91 = 1/295
Axis of the earth is inclined gives
4 seasons
23 1/2°
6864.57nm
6887.91nm
66 1/2°
Oblate Sphere
Perfect Sphere
Earth and Coordinates
Circle on a Sphere
• Great Circle
– Plane can pass through the center of the sphere
• Meridian of Longitude or a meridian
– Half of a great circle passing through the poles is The
Meridian of Longitude or meridian
– Prime meridian is the great circle
passing through Greenwich,
England
– Longitude is measured around
The earth both eastward and west ward
from Prime meridian, through 180°
• Small Circle
– Any circle formed by a plane which does not
pass through the center of the sphere
– Latitude or Parallel of Latitude except Equator 0°
– Latitude range from 0° at the equator to 90°N
and 90°S at the pole
– Any of latitude other than
the equator is
0°
0°
a small circle parallel to it
“Parallel of Latitude”
“Parallel”
• Segments of a circle, called arcs, are
measured in degrees, minutes, and seconds
• Any circle is divided into 360 equal parts ,
each curved arc would be 1° in length
• A degree is divided into 60 equal parts forms
arcs of 1 minute each, and one sixtieth of
minute is a second
• For very fine measurement beyond a
second, decimal parts are used
• 8°40’7.18’’
• All meridians intersect at right angles with
parallels of latitude
“A small circle is formed on the surface of the earth by intersection
of a plane which dose not pass through the center of the earth.”
“Great circle – Pass through
the center of the earth”
เส้ นเกลียว(Rhumb line)
คือ เส้ นที่ตัดเส้ นเมอริเดียนถัด ๆ
ไป ด้ วยมุมคงที่
MAP and CHART
• MAP is a small scale, flat surface
representation of some portion of the earth
surface such a representation design for
NAV.
• Term maps and charts are used
interchangeably.
• A map is to look at, a chart is to work on.
– Enroute charts, approach charts
Map Projection
• A round surface cannot be flattened
without some stretching, wrinkling, or
tearing called “Distortion”
• To minimize errors
• The framework of meridians and parallels
on any map is called “the Graticule”
Definition of Map Terms
• Statue Mile (s.m.): a distance as 5,280 ft
• Nautical Mile (n.m.) : a distance as 6,080 ft
or 1.15 s.m. It is the length of a minute of
arc on the equator ; since the equator is a
great circle, one minute of arc will be a
nautical mile on any Great Circle, and
hence distance can be measured along
any meridian.