1. Latitude, Longitude, Earth's Magnetism & Compass Errors4 . 2
Latitude, Longitude, Earth's Magnetism & Compass Errors

2. Meridians of Longitude and Parallels of Latitude
circles on the earth’s surface whose planes lie parallel to the equator
equator is a great circle on the surface of the earth lying equidistant from the poles
measured from 0° to 90° north and south of equator
measured in degrees (°), minutes (’) and seconds (”)
semi great circles joining the true or geographic poles of the earth (true meridians)
measured from 0° to 180° east and west of prime meridian
180th meridian is called the International Date Line
measured in degrees (°), minutes (’) and seconds (”)
Note: there are 60 minutes in a degree and 60 seconds in a minute

3. Determining Geographical Coordinates
Intersection of the lines of latitude and longitude marking a position on a map
used to locate a fixed object on the earth’s surface
change of latitude and the change of longitude between two places relate one position on the surface with another

4. Time and Longitude
Solar Day - interval between two successive transits of the sun. It is divided into 24 hours.
The sun travels around the earth once every day. It travels 360 degrees of longitude in one day.
Time can therefore be expressed in terms of longitude:
24 hours degrees longitude
1 hour - 15 degrees longitude
1 min - 15 minutes longitude
1 sec - 15 seconds longitude

5. Time and Longitude cont’d
360 degrees longitude - 24 hours
1 degree longitude - 4 min
1 minute longitude - 4 sec
1 second longitude - 1/15 sec

6. Coordinated Universal Time (UTC)
Used so that a universal standard time exists for reference at any point on the earth
based upon measurements of time in a number of places on the earth.
It is also referred to as Z or zulu time.
UTC replaced Greenwich mean time (GMT), which was once the universally accepted standard.
UTC is the local mean time for the prime meridian.
Winter time is the same as Standard Time.

7. NOTE: You must use the buttons in the Confirmation Stage

8. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #1 - Name a semi great circle joining the true poles of the earth. A
Meridians of longitude B
Parallels of latitude C
Meridians of latitude D
Parallels of longitude

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13. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #2 - What is the length of 15° longitude? A
24 hours B
1 hour C
1 minute D
1 second

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18. Magnetism True North is the north pole of the earth.
Magnetic North is the direction the compass needle lies without considering deviation.
Magnetic north is not a fixed position.
The magnetic field of the earth changes as magnetic north moves about in a circle.

19. Magnetic Variation
Defined as the angle between the true meridian and magnetic meridian in which the compass needle lies.
It is also known as magnetic declination in other disciplines.

20. Converting between True and Magnetic Heading
To convert from True to Magnetic Heading:
Add Westerly Variation
Subtract Easterly Variation
Example:
True Heading: 320°
Variation: 6° West
Find Magnetic Heading.
320° + 6° =
326°

21. To convert from Magnetic to True Heading:
Add Easterly Variation
Subtract Westerly Variation
Example:
Magnetic Heading: 256°
Variation: 3° West
Find True Heading
256° - 3° =
253°

22. Helpful Reminder
East is Least West is Best

23. Compass Deviation
The angle between the magnetic heading and the compass heading.
Compass heading is magnetic heading corrected for deviation.

24. Converting between Magnetic and Compass Heading
To convert from Magnetic to Compass:
Add Westerly Deviation
Subtract Easterly Deviation
Example:
Magnetic Heading: 050°
Deviation: 2° West
Find Compass Heading.
050° + 2° =
052°

25. To convert from Compass to Magnetic
Add Easterly Deviation
Subtract Westerly Deviation
Example:
Compass Heading: 201°
Deviation: 1° West
Find Magnetic Heading.
201° - 1° =
200°

26. All variation and deviation can be remembered by:
T - True Track
V - Variation
M - Magnetic Heading
D - Deviation
C - Compass Heading

27. NOTE: You must use the buttons in the Confirmation Stage

28. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #3 - What is the angle between the true meridian and the magnetic meridian? A
Magnetic heading B
Compass heading C
Variation D
Deviation

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33. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #4 - If your aircraft has a true heading of 240° and there is a variation of 20° West, what is the magnetic heading? A
220° B
260° C
240° D
250°

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38. Compass Errors
A compass has several errors which may lead it to not point directly to magnetic north.
Knowledge of their presence will assist the pilot in correcting for them.

39. Magnetic Dip
The earth’s lines of force are horizontal at the equator but become vertical towards the poles.
Causes the compass to tend to dip in higher latitudes.

40. Northerly Turning Error
The compass will misread when the aircraft is in a banked attitude and turning.
Error is most apparent on headings of north and south and is greatest over the poles.
Always make sure the wings are level while reading the compass on north or south headings.

41. On turns from the north, northerly turning error causes the compass to lag.
On turns from the south, northerly turning error causes the compass to lead.

42. Acceleration Error
On east and west headings, acceleration causes a turning moment, tending to rotate the magnet system and so causing deflection of the compass card.
When the airplane decelerates, a similar effect is seen but the deflection will be in the opposite direction.
The effect of acceleration and deceleration compass errors is nil on north and south headings.
When reading the compass on east or west headings, always make sure that airspeed is constant.

43. While flying an east/west heading, acceleration causes the
compass to register a turn to the north.
While flying an east/west heading, deceleration causes the
compass to register a turn to the south.

44. NOTE: You must use the buttons in the Confirmation Stage

45. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #5 - The error on turns from north where the compass lags is known as A
Magnetic dip B
Acceleration and deceleration error C
Northerly turning error D
Easterly and westerly error

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50. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Let's try a few review questions on Navigation:
Question #6 - The compass needle dips toward the surface of the earth at the poles. What is this error called? A
Magnetic dip B
Acceleration and deceleration error C
Northerly turning error D
Easterly and westerly error

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55. Navigation Latitude, Longitude, Earth’s Magnetism, and Compass Errors
Congratulations!!
You have now completed the Latitude, Longitude, Earth’s Magnetism, and Compass Errors lesson of the Navigation Module. Of course, this lesson is always available to you for future reference if required.
You are now ready to move along to the next Navigation lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam.
Good Luck!