4 . 1 Definitions

Great Circle A circle on the surface of the earth whose plane passes through the center of the earth. It is also the shortest distance between two points on the surface of the earth.

Rhumb Line A curved line on the surface of the earth cutting all meridians at the same angle. All parallels of latitude are rhumb lines.

Measurement of Direction Direction is measured in degrees clockwise from north which is 0° (or 360°). East is 90°, south is 180° and west is 270°.

Headings The direction that the aircraft nose (longitudinal axis) is pointing, measured clockwise from north. True heading is measured from true north. Magnetic heading is measured from magnetic north. Graphic updated.

Isogonic Lines Lines on a map joining places of equal variation. Also known as isogonals. These are numbered east and west according to whether the magnetic variation is to the east or west of true north.

Agonic Lines Lines on a map joining places of zero variation. Included map of Agonic Line in USA

Variation Defined as the angle between the true meridian and magnetic meridian. It is also referred to as magnetic variation.

Deviation Compass Heading The angle between compass heading and magnetic heading. The difference is caused by the magnetic fields generated from the metal airframe and engine. Compass Heading The direction that the needle in the compass is pointing.

NOTE: You must use the buttons in the Confirmation Stage

Navigation Definitions Let's try a few review questions on Navigation: Question #1 - What is curved line on the surface of the earth cutting all meridians at the same angle? A Heading B Magnetic heading C Great circle D Rhumb line

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Navigation Definitions Let's try another question on Navigation: Question #2 - What lines join places of zero variation? A Agonic lines B Isogonals C Rhumb lines D Great circle

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Bearings The position of an object relative to your aircraft. This angle is also known as the azimuth. Measured clockwise from the meridian through 360°. Has nothing to do with aircraft heading.

Standard Measurements Of Distance Statute Mile - Distance measuring 5280 feet. Nautical Mile - Average length of one minute of latitude: 6080 feet. Kilometer - 1000 meters.

Standard Measurements of Speed Speed - The rate at which an object moves in relation to a fixed object. Miles per Hour (MPH) - Speed in statute miles per hour. Knot - Speed in nautical miles per hour. Kilometers per hour (KPH) - Speed in kilometers per hour.

Airspeeds and Groundspeed Indicated Airspeed - Speed shown on the airspeed indicator. True Airspeed - Speed of the aircraft relative to the air. Groundspeed - Speed of the airplane relative to the ground.

Track The direction an airplane intends to travel over the ground. May be represented by a straight line drawn on a map. Also known as intended track or required track. Direction is the angle between this line and a meridian measured clockwise through 360°. Can be true, magnetic or compass.

Track Made Good Actual path traveled by the airplane over the ground. Like track, it may be represented by a line drawn on a map and its direction measured (if it is reasonably straight line).

Drift Drift, or drift angle, is the angle between the heading being flown and the track made good over the ground. It can be expressed in degree either left or right.

NOTE: You must use the buttons in the Confirmation Stage

Navigation Definitions Let's try a few review questions on Navigation: Question #3 - What is the length of a nautical mile? A 5280 feet B 6080 feet C 5280 meters D 6080 meters

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Navigation Definitions Let's try a few review questions on Navigation: Question #4 - What is the actual track the aircraft flies over the ground? A Bearing B Track C Track made good D Drift

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Flying Scholarship Program That answer is correct. Let's move on...

Navigation Definitions Congratulations!! You have now completed the Definitions 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!