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What does 'variation' refer to in navigation?
The difference between true bearing and magnetic bearing
The error in compass readings during flight
The adjustment needed for altitude
The speed of the aircraft relative to wind
The correct answer is: The difference between true bearing and magnetic bearing
In navigation, 'variation' specifically refers to the difference between true bearing and magnetic bearing. It is a crucial concept for pilots and navigators, as it helps them understand how to correct their compass readings to ensure accurate navigation. True bearing is the angle measured in degrees from true north, while magnetic bearing is the angle measured from magnetic north, which is influenced by the earth's magnetic field. Because these two north references do not perfectly align due to variations in the magnetic field, knowing the variation allows navigators to adjust their course appropriately. This ensures that the heading they follow corresponds accurately to the intended route over the ground. The other choices address different aspects of navigation; for instance, the error in compass readings during flight involves other navigational corrections but is not specifically defined as 'variation.' The adjustment needed for altitude is related to vertical navigation, while the speed of the aircraft relative to wind describes performance rather than directional orientation. Understanding variation is essential for precise navigation, making it critical for safe and effective aircraft operation.