The magnetic compass
Steering you straight
And they are, particularly when you consider the level of computerization in today’s car engines. But the airplane engine’s got nothin’ on the most basic piece of navigation equipment commonly found in aircraft: the magnetic compass. Its technology dates back to the 11th or 12th century, when historians believe China first used the magnetic compass for navigation.
Since it made the inevitable leap to aviation, the magnetic compass has been standard equipment—a hard-working and reliable tool that doesn’t require much maintenance. The instrument bobbing away on your airplane’s glareshield or instrument panel has very few parts: a compass card that swings on a pivot, two magnets and a float. The parts are submerged in mineral spirits or kerosene. The face of the instrument has a reference point called a lubber line, where the direction you’re headed is referenced.
Old reliable
It’ll work just fine, but you’ll want to remember that when reading it the compass appears backward. This is because you’re reading the back side of the compass. For example, when turning right from a heading of 360 to 090, the compass rotates counter-clockwise, making it look like you’re turning left.
New look
A vertical card compass has a compass card oriented vertically so that when the aircraft turns, the card shows a turn in the same direction. It looks more like a heading indicator, which makes it somewhat easier to read. Owners of vintage aircraft will frequently update wet compasses with the somewhat more modern vertical card compass. Both types of compasses, however, have inherent errors: variation, deviation, dip error, turning error, acceleration error, and oscillation error.
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