Navigation

3.01 Foundations of NavigationReferences:

FTGU pages 177-178, 184-190Transport Canada Study and Reference Guide Glider PilotCanada 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

• What is the approximate latitude and longitude of each letter?

A.______________________ B._______________________C. ______________________ D. _______________________

A

BC

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