Magnetic CompassMagnetic Compass

Magnetic CompassMagnetic Compass

Oldest and most reliable instrumentOldest and most reliable instrument Construction of CompassConstruction of Compass

Two bar magnetsTwo bar magnets Jeweled bearingJeweled bearing Compass cardCompass card Expansion chamberExpansion chamber Compass fluidCompass fluid Compensating magnetCompensating magnet Compass weightCompass weight Lubber lineLubber line

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Different errorsDifferent errors

OscillationOscillationVariationVariationDeviationDeviationCompass dipCompass dipNortherly turningNortherly turningAccelerationAcceleration

OscillationOscillation

Result of movementResult of movementWeights in compassWeights in compass

CorrectionCorrectionTake average headingTake average heading

VariationVariation

Difference of true and magnetic northDifference of true and magnetic north

CorrectionCorrectionUse chart correctionUse chart correction

DeviationDeviation

Errors in indicated heading due to local Errors in indicated heading due to local magnetic fieldsmagnetic fields

Different in each airplaneDifferent in each airplane

CorrectionCorrectionWeights in compassWeights in compassCorrection in airplaneCorrection in airplane

Compass DipCompass Dip

The angle of magnetic flowThe angle of magnetic flow

CorrectionCorrectionWeight installed in compassWeight installed in compass

Compass unbalanced to compensate for Compass unbalanced to compensate for vertical fieldvertical field

Unbalanced condition causes compass to Unbalanced condition causes compass to overshoot north and undershoot southovershoot north and undershoot south

CorrectionCorrectionUN/OSUN/OSUndershoot NorthUndershoot NorthOvershoot SouthOvershoot South

Northerly Turning ErrorsNortherly Turning Errors

Acceleration ErrorAcceleration Error

When heading east or westWhen heading east or west Compass indicates north on accelerationCompass indicates north on acceleration Compass indicates south on decelerationCompass indicates south on deceleration

CorrectionCorrection ANDSANDS Use compass only on straight and level flightUse compass only on straight and level flight

ConclusionConclusion

ReliableReliableErrorsErrors

OscillationOscillation VariationVariation DeviationDeviation Compass DipCompass Dip Northerly turning errorsNortherly turning errors Acceleration errorsAcceleration errors

Be aware of correctionBe aware of correction UNOS & ANDSUNOS & ANDS ECTECT