30 Questions
What is the primary function of a direct-reading magnetic compass?
To show the direction in which an aircraft is heading with respect to the Earth's magnetic meridian
At what location on the Earth's surface are the lines of force horizontal to the surface?
At the magnetic equator
What is the angle of magnetic inclination at the magnetic poles?
90 degrees
What emerges vertically at the north magnetic pole?
The lines of force
What type of compass incorporates both the magnetic sensing element and display element in one component?
A direct-reading compass
Why is it important for the pilot to correct for variation when navigating?
To take variation into account
What is a desirable property of a liquid used in a compass?
Low freezing point
What is the purpose of a flexible element in a liquid-filled compass?
To compensate for changes in the liquid's volume due to temperature changes
What happens to the liquid in a compass when it is subjected to low temperatures?
It contracts and decreases in volume
What can cause a compass to become unserviceable?
External leaks or air bubbles
Why is low power lighting used in compass illumination?
To prevent interference with the compass's accuracy
What type of cable is often used to supply power to a compass's illumination?
Screened cable or a twisted pair
What is the primary cause of deviation in an aircraft's magnetic compass?
Local magnetic fields in the aircraft
What is the purpose of the compass compensation phase in the calibration procedure?
To adjust the compass to obtain minimum residual deviation error
What is the result of the compass calibration process?
A compass correction card
What can affect the Earth's magnetic field in an aircraft?
Components fitted to an aircraft that contain iron
When can deviation error be minimised?
During compass calibration
What is the purpose of the compass correction card?
To correct for deviation errors during flight
What is the primary factor affecting compass accuracy on north-south headings?
Coefficient C error
Where are the compensator magnets located?
In the longitudinal axis
What is the purpose of the compass calibration proforma?
To simplify the compensation process
When is the compass compensation and adjustment procedure performed?
At all of the above occasions
What is the result of not correcting for coefficient C error?
Inaccurate compass readings on north-south headings
What is the final step in the compass compensation process?
Recording the calibration on a compass calibration card
What is the main purpose of rotating the compass or flux valve in relation to Coefficient A?
To correct for installation error and read the correct heading
When does the magnetism in the fuselage affect compass accuracy the most?
When the aircraft is heading east or west
What is the purpose of the compensator magnets located in the lateral axis of the aircraft?
To correct for Coefficient B error
What is Coefficient C error primarily caused by?
An imaginary magnet lying along the aircraft's lateral axis
Why does the fuselage magnetism not modify the magnetic meridian when the aircraft is heading north or south?
Because the Earth's lines of flux travel north-south
What is the orientation of the imaginary magnet that causes Coefficient B error?
Along the fore and aft axis of the aircraft fuselage
Test your understanding of aeroplane aerodynamics and navigation principles, including magnetic inclination and its effect on navigation. Learn how pilots correct for variations in magnetic fields when navigating.
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