What is the purpose of the horizon bar on an artificial horizon?

• A. To display the aircraft’s speed
• B. To provide reference for maintaining level flight
• C. To indicate fuel levels
• D. To show engine temperature

Answer: (B)

The horizon bar on an artificial horizon serves as a critical reference point for pilots to maintain level flight. This instrument portrays the relationship between the aircraft's orientation relative to the true horizon. When the airplane is in level flight, the horizon bar aligns with a specific reference line, indicating to the pilot that no bank or pitch is occurring. In conditions of reduced visibility, such as in clouds or at night, this visual aid becomes essential for safe flying. By observing the position of the horizon bar in relation to the aircraft symbol, pilots can make necessary adjustments to ensure that the aircraft remains straight and level, which is vital for stable flight and aircraft control.

The remaining options do not relate to the function of the horizon bar. The instrument does not display speed, fuel levels, or engine temperature, which are monitored by separate instrumentation specifically designed for those purposes.