How does an attitude indicator work and what information does it provide?

The attitude indicator (artificial horizon) displays aircraft pitch and roll relative to the horizon. Traditional mechanical versions use a gyroscope that maintains a fixed reference in space; the aircraft rotates around it, indicating attitude. Modern systems use AHRS (Attitude and Heading Reference System) with solid-state sensors (MEMS accelerometers and gyros) and algorithms to compute attitude. The display shows a miniature aircraft symbol against a horizon line, with pitch marks and bank angle indication. Attitude is the most critical flight instrument, essential for flying in clouds or at night. Redundant systems (typically 3 IRS/AHRS) ensure availability.