What does the lubber line on a directional gyro represent?

The lubber line on a directional gyro represents the nose of the aircraft. It is a fixed reference line that aligns with the aircraft’s longitudinal axis, indicating the direction in which the aircraft is heading. When the gyro is properly calibrated and functioning, the position of the lubber line will show the pilot the aircraft's current heading relative to magnetic north. This information is crucial for navigation and ensuring that the aircraft is flying in the correct direction. Understanding the role of the lubber line helps pilots maintain a sense of direction and make informed navigation decisions.