777 Neptune Groundschool Navigation

The Graticule The Graticule is a system of (imaginary) intersecting lines along the surface of the earth Its purpose is for fast and accurate location Consists of Meridians of Longitude that run north – south, measuring East and West Parallels of Latitude that run East – West, measuring North and South

Navigation terms Pilotage is navigation with reference only to landmarks Dead Reckoning is navigation via a predetermined route factoring wind, true airspeed, heading, groundspeed, and an estimated time of arrival Radio Navigation is navigation by use of radio waves Inertial Navigation is navigation via a built in compass Satellite Navigation is navigation via use of GPS The act of navigation consists of these various methods in combination with each other

Heading and Bearing Heading is the direction of the longitudinal axis measured in degrees clockwise from north North is 0 or 360 East is 90 South is 180 West is 270 Bearing is the measured of an angle between an observer and the object measures clockwise from north with reference to the observer

Variation The earth has two North Poles True north – an arbitrary point on earth Magnetic north – the north that all compasses point to In special cases, where an observer stands, true north = magnetic north, in which case the observer is on an Agonic Line – line joining area of no variation In most cases, the where the observer stands, true north ≠ magnetic north, in which case the observer is on an Isogonic Line – line joining areas of equal variation The difference (in degrees) between true and magnetic north is Variation

Deviation In an ideal world, a magnetic compass would point exactly to magnetic north This is not the case due to interferences by external sources (other magnets, electronic waves, ect) To account for this, we use Deviation – the difference between magnetic north, and the direction that the compass is pointing in

Determining heading We now know that not all heading are the same, we have True heading – based off true north Magnetic heading – based off magnetic north Compass heading – bases off the direction the compass points When flying you have no way to actively determine true or magnetic north, only you compass heading Compass heading is different, therefore there must be a way to convert between headings

Calculation of true, magnetic and compass heading True heading Variation Magnetic heading Deviation Compass heading +/- variation True Track Magnetic Track +/- drift +/- drift +/- deviation +/- variation True Heading Compass Heading Magnetic Heading

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 320° 6° West ??? Example: True heading: 320° Variation: 6° West Magnetic Heading ???

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 320° 6° West 326° Example: True heading: 320° Variation: 6° West Magnetic Heading 320° + 6° = 326°

??? The other way around… West (-) East (+) ??? 3° West 256° Example: True Heading Variation Magnetic Heading Deviation Compass heading ??? 3° West 256° Example: Compass heading: 256° Deviation: 3° West Magnetic haeading. ???

256° - 3° = 253° The other way around… West (-) East (+) 253° 3° West True Heading Variation Magnetic Heading Deviation Compass heading 253° 3° West 256° Example: Compass heading: 256° Deviation: 3° West Magnetic haeading. 256° - 3° = 253°

??? ??? West (-) East (+) 5° West 005° Example: Compass heading: 005° True Heading Variation Magnetic Heading Deviation Compass heading ??? 5° West 005° Example: Compass heading: 005° Deviation: 5° West Magnetic haeading. ???

005° - 5° = 360° West (-) East (+) 360° 5° West 005° Example: True Heading Variation Magnetic Heading Deviation Compass heading 360° 5° West 005° Example: Compass heading: 005° Deviation: 5° West Magnetic haeading. 005° - 5° = 360°

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 010° 020° 3° East Example: True heading: 010° Variation: ??? Magnetic Heading 010° + ???° = 020°

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 010° 020° 3° East Example: Magnetic Heading: 020° True heading: 010° Variation 020° - 010° = 010° West

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 010° 010° West 020° 3° East ??? Example: Magnetic Heading: 020° Deviation: 3° East Compass Heading ???

Calculation of true, magnetic and compass heading West (+) East (-) True Heading Variation Magnetic Heading Deviation Compass heading 010° 010° West 020° 3° East 017° Example: Magnetic Heading: 020° Deviation: 3° East Compass Heading 020° - 003° = 017°

??? 12° East ??? West (-) East (+) 4° West 005° Example: True Heading Variation Magnetic Heading Deviation Compass heading 12° East ??? 4° West 005° Example: Compass heading: 245° Deviation: 4° West Magnetic haeading. ???

005° - 004° = 001° 12° East 001° West (-) East (+) 4° West 005° True Heading Variation Magnetic Heading Deviation Compass heading 12° East 001° 4° West 005° Example: Compass heading: 245° Deviation: 4° West Magnetic haeading. 005° - 004° = 001°

??? 12° East 001° West (-) East (+) ??? 4° West 005° Example: True Heading Variation Magnetic Heading Deviation Compass heading ??? 12° East 001° 4° West 005° Example: Magnetic Heading: 241° Variation: 12° East True Heading ???

001° + 012° = 013° 12° East 001° West (-) East (+) 013° 4° West 005° True Heading Variation Magnetic Heading Deviation Compass heading 013° 12° East 001° 4° West 005° Example: Magnetic Heading: 241° Variation: 12° East True Heading 001° + 012° = 013°

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