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Pilot's Handbook of Aeronautical Knowledge
Flight Instruments
Compass Systems

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Pilot's Handbook of Aeronautical Knowledge

Preface

Acknowledgements

Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making

Appendix

Glossary

Index

Northerly turning error.
Figure 7-35. Northerly turning error.

The pull of the vertical component of the Earth's magnetic field
causes northerly turning error, which is apparent on a heading
of north or south. When an aircraft flying on a heading of north
makes a turn toward east, the aircraft banks to the right, and
the compass card tilts to the right. The vertical component of
the Earth's magnetic field pulls the north seeking end of the
magnet to the right, and the float rotates, causing the card to
rotate toward west, the direction opposite the direction the turn
is being made. [Figure 7-35]

If the turn is made from north to west, the aircraft banks to
the left and the compass card tilts down on the left side. The
magnetic field pulls on the end of the magnet that causes the
card to rotate toward east. This indication is again opposite to
the direction the turn is being made. The rule for this error is:
when starting a turn from a northerly heading, the compass
indication lags behind the turn.

When an aircraft is flying on a heading of south and begins
a turn toward east, the Earth's magnetic field pulls on the
end of the magnet that rotates the card toward east, the same
direction the turn is being made. If the turn is made from
south toward west, the magnetic pull starts the card rotating
toward west—again, in the same direction the turn is being
made. The rule for this error is: when starting a turn from a
southerly heading, the compass indication leads the turn.

In acceleration error, the dip-correction weight causes the end
of the float and card marked N (the south-seeking end) to be
heavier than the opposite end. When the aircraft is flying at
a constant speed on a heading of east or west, the float and
card is level. The effects of magnetic dip and the weight are
approximately equal. If the aircraft accelerates on a heading
of east [Figure 7-36], the inertia of the weight holds its end of
the float back and the card rotates toward north. As soon as the
speed of the aircraft stabilizes, the card swings back to its east
indication. If, while flying on this easterly heading, the aircraft
decelerates, the inertia causes the weight to move ahead and the
card rotates toward south until the speed again stabilizes.

Effects of acceleration error.
Figure 7-36. Effects of acceleration error.
 

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