Navigation
3.01 Foundations of Navigation
References:
FTGU pages 177-178, 184-190
Transport Canada Study and Reference Guide Glider Pilot
Canada Flight Training Manual – Pilot Navigation
http://en.wikipedia.org/wiki/Transverse_Mercator_projection#Spherical_transverse_Mercator
3.01 Foundations of Navigation
• MTPs:
– Longitude and Latitude
– Time and Longitude
– Charts
– Lambert Conformal Conic Projection
– Transverse Mercator Projection
– Great Circles and Rhumb Lines
– Magnetic Navigation
– Units of Distance and Speed
Longitude and Latitude
• Imaginary lines make up a grid
on the surface of the earth.
• Parallels of Latitude run east to
west (like the equator), and are
numbered 0 to 90 degrees
North and South from the
equator.
• Meridians of Longitude run
north to south and are
numbered 0-180 degrees East
and West from the Prime
Meridian.
Longitude and Latitude
• Latitude is
measured in
degrees,
minutes and
seconds and
includes “north”
or “south”.
• The equator is
at 0 degrees
latitude.
• Point A is at 15
degrees north.
Longitude and Latitude
• Longitude is
measured in
degrees, minutes
and seconds and
includes “east” or
“west”.
• The Prime
Meridian is at 0
degrees longitude.
• Point A is at about
22 degrees west.
Longitude and Latitude
•
•
•
Coordinates are given by grouping the
latitude and longitude of a point together
in that order
Each degree is broken into 60’ (minutes)
and each minute is broken into 60”
(seconds)
The coordinates for Moose Jaw,
Saskatchewan are:
50°23′36″N 105°33′07″W
Confirmation
C
B
D
A
•
What is the approximate latitude and longitude of each letter?
A.______________________ B._______________________
C. ______________________ D. _______________________
Confirmation
See if you can find the latitude and longitude for
your home town. Google it and report it in the
chat box!
Time and Longitude
• Because the earth rotates, the sun appears to pass over
a fixed point on the earth at a rate that varies throughout
the year
– If we take an average throughout the year, we can calculate the
mean solar day
• The mean solar day is divided into 24 equal hours
– Each hour, the earth will rotate approximately 15 degrees
– It will take the earth 4 minutes to rotate approximately 1 degree
• This rate actually appears to vary, so we use a common
reference
– UTC (coordinated universal time) or Z (“Zulu” time)
• Time at the prime meridian
– Time zones are expressed in hours behind or ahead of UTC or Z
• E.g. PST is UTC -8 and PDT is UTC -7
Charts
• What is a chart?
• Basic Elements of Map Construction:
–
–
–
–
Area
Shape
Bearing
Distance
• Normally one of the
elements is closely
preserved, the others
become distorted.
Charts
• Projections are the mathematical basis upon which maps
are constructed
• Types of projections:
Cylindrical
Conic
Azimuthal
Lambert Conformal Conic Projection
• Parallels of Latitude are curved, and
• Meridians of Longitude converge at the
pole.
Lambert Conformal Conic Projection
Transverse Mercator Projection
Mercator Projection
Parallels of
Latitude
and
Meridians
of
Longitude
are straight
lines that
form a grid.
Great Circles and Rhumb Lines
• A great circle is a line that cuts the earth
perfectly in half, and represents the shortest
distance between two points
– An example of a great circle is the equator
• A rhumb line is a line which cuts each meridian it
crosses at the same angle
– A line which could be made
by flying the same heading
Great Circles and Rhumb Lines
 Drawing a straight line on different projections will yield
different results
 Lambert Conformal Conic Projection
 Great Circle
 Mercator (not Transverse Mercator)
 Rhumb Line
Magnetic Navigation
 The earth generates a magnetic field which is useful for
navigation using a compass
 This magnetic field is not perfectly aligned with the axis of
rotation
 This creates a magnetic north which is in a different geographic
location from true north
 The angular difference between true
north and magnetic north is known
as variation
 This is expressed in degrees east or
west of true north
Magnetic Navigation
• Isogonic lines connect areas of equal variation
• Agonic lines connect areas of 0 variation
Magnetic Navigation
• It is possible to convert a true heading to a
magnetic heading or a compass heading using
the TVMDC method
• More on doing this, and on using a compass, in
3.03
Units of Distance and Speed
• 1 Statute Mile (SM) is 5 280 feet
• 1 Nautical Mile (NM) is 6 080 feet
–1 Knot is 1 Nautical Mile per Hour
• The ratio of 1 NM to 1 SM is 1.15
Confirmation
Identify the type of projection. What are its characteristics?
Confirmation
Identify the type of projection. What are its characteristics?
1650 Map of the Ancient World