What does HSI stand for in aviation navigation?

HSI in aviation navigation stands for Horizontal Situation Indicator. It is an important instrument used in aircraft cockpits that provides pilots with critical information about their navigation status. The HSI displays the aircraft's current heading as well as guidance information from the navigation system, including the direction to a selected waypoint or the desired course.

The HSI integrates data from various navigation sources, such as VOR, localizer, and GPS, making it easier for pilots to understand their position relative to the desired flight path. The horizontal aspect refers to the presentation of this information in a two-dimensional format, allowing pilots to visualize their current trajectory in relation to their intended route. The clarity and functionality of the HSI greatly aid in situational awareness, especially during navigation and approach phases of flight.