Meridians of Longitude and Parallels of Latitude semi great circles joining the true or geographic poles of the earth (true meridians) measured from.

Meridians of Longitude and Parallels of Latitude

• 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 (”)

• 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 (”)

Meridians of Longitude Parallels of Latitude

Note: there are 60 minutes in a degree and 60 seconds in a minute

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

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 - 360 degrees

longitude

– 1 hour - 15 degrees longitude

– 1 min - 15 minutes longitude

– 1 sec - 15 seconds longitude

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

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.

Confirmation Stage

NOTE: You must use the buttons in the Confirmation Stage

A

B

C

D

Meridians of longitude

Parallels of latitude

Meridians of latitude

Parallels of longitude

Let's try a few review questions on Navigation:

Question #1 - Name a semi great circle joining the true poles of the earth.

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Meridians of Longitude and Parallels of Latitude

• 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 (”)

• 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 (”)

Meridians of Longitude Parallels of Latitude

Note: there are 60 minutes in a degree and 60 seconds in a minute

A

B

C

D

24 hours

1 hour

1 minute

1 second

Let's try a few review questions on Navigation:

Question #2 - What is the length of 15° longitude?

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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 -360 degrees longitude

–1 hour -15 degrees longitude

–1 min -15 minutes longitude

–1 sec -15 seconds longitude

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.

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.

Converting between True and Magnetic Heading

• To convert from True to Magnetic Heading:– Add Westerly Variation– Subtract Easterly Variation

320° + 6° = 326°

Example: True Heading: 320°

Variation: 6° WestFind Magnetic Heading.

• To convert from Magnetic to True Heading:– Add Easterly Variation– Subtract Westerly Variation

256° - 3° = 253°

Example: Magnetic Heading: 256°

Variation: 3° WestFind True Heading

Helpful Reminder

East is Least West is Best

Compass Deviation

The angle between the magnetic heading and the compass heading.

Compass heading is magnetic heading corrected for deviation.

Converting between Magnetic and Compass Heading

• To convert from Magnetic to Compass:– Add Westerly Deviation– Subtract Easterly Deviation

050° + 2° = 052°

Example: Magnetic Heading: 050°

Deviation: 2° WestFind Compass Heading.

• To convert from Compass to Magnetic– Add Easterly Deviation– Subtract Westerly Deviation

201° - 1° = 200°

Example: Compass Heading: 201°

Deviation: 1° WestFind Magnetic Heading.

All variation and deviation can be remembered by:

T - True Track

V - Variation

M - Magnetic Heading

D - Deviation

C - Compass Heading

Confirmation Stage

NOTE: You must use the buttons in the Confirmation Stage

A

B

C

D

Magnetic heading

Compass heading

Variation

Deviation

Let's try a few review questions on Navigation:

Question #3 - What is the angle between the true meridian and the magnetic meridian?

NavigationNavigationLatitude, Longitude, Earth’s Magnetism, and Compass Errors Latitude, Longitude, Earth’s Magnetism, and Compass Errors

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Magnetic Variation Defined as the angle between the true

meridian and magnetic meridian inwhich the compass needle lies.

It is also known as magneticdeclination in other disciplines.

A

B

C

D

220°

260°

240°

250°

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?

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Converting between True andMagnetic Heading

• To convert from True to Magnetic Heading:– Add Westerly Variation

– Subtract Easterly Variation

240° + 20° = 260°

Example: True Heading: 240°

Variation: 20° WestFind Magnetic Heading.

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.

Magnetic DipThe 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.

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.

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.

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.

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.

NOTE: You must use the buttons in the Confirmation Stage

A

B

C

D

Magnetic dip

Acceleration and deceleration error

Northerly turning error

Easterly and westerly error

Let's try a few review questions on Navigation:

Question #5 - The error on turns from north where the compass lags is known as .

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Northerly Turning Error The compass will misread when the

aircraft is in a banked attitude and turning.

Error is most apparent on headings ofnorth and south and is greatest over thepoles.

When reading the compass when holdingnorth or south headings, always make surethe wings are level.

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?

NavigationNavigationLatitude, Longitude, Earth’s Magnetism, and Compass Errors Latitude, Longitude, Earth’s Magnetism, and Compass Errors

A

B

C

D

Magnetic dip

Acceleration and deceleration error

Northerly turning error

Easterly and westerly error

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Magnetic DipThe 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.

Congratulations!!

You have now completed the Latitude, Longitude, Earth’s Magnetism, Latitude, Longitude, Earth’s Magnetism, and Compass Errorsand 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!

NavigationNavigationLatitude, Longitude, Earth’s Magnetism, and Compass Errors Latitude, Longitude, Earth’s Magnetism, and Compass Errors