The attitude indicator (AI), also known as the artificial horizon, uses an internal gyro to display the aircraft’s attitude relative to the horizon. The display consists of a representation of an aircraft aligned to the horizon in straight-and-level flight, with a blue sky above and brown or black ground below.
A vertical scale crossing the horizon shows degrees of pitch up or down. A curved scale across the top shows degrees of bank left or right. When the aircraft changes pitch or direction, the aircraft rotates around the AI’s gyro and the instrument display responds accordingly.
Markings
The curved bank angle markings around the top of the indicator are 10°, 20°, 30°, 45° (the triangle), 60° and
90°.
The horizontal line pitch markings are degrees of nose up or down, in 10° increments.
In use
If you compare the movement of the horizon line in the attitude indicator with the movement of the natural horizon, you will see that the instrument instantly and accurately reflects changes in the pitch and roll attitude of the airplane.
It is this instantaneous representation that makes the attitude indicator the most valuable instrument on the panel when reference to the natural horizon is lost.
When you can’t see the horizon and must maintain the airplane’s attitude by instruments alone, don’t bank any more than ten degrees (the first reference mark at the top of the attitude indicator).