Horizontal Situation Indicator

The Horizontal Situation Indicator (HSI) is a type of navigational instrument that falls under the supply class of Navigational Instruments in the supply group of Instruments And Laboratory Equipment.

The HSI is a primary flight instrument used in aircraft to provide pilots with essential information about their horizontal position and orientation relative to the earth's surface. It combines the functionality of a heading indicator and a course deviation indicator into a single display.

The HSI typically consists of a compass rose that indicates the aircraft's heading, a course deviation indicator (CDI) that shows the deviation from the desired course, and a horizontal situation indicator that displays the aircraft's position relative to the selected navigation source, such as a VOR (VHF Omnidirectional Range) or an ILS (Instrument Landing System).

The HSI allows pilots to easily interpret their position and track their course during flight, making it an essential tool for navigation and situational awareness. It provides information on the aircraft's heading, course, and position, allowing pilots to make accurate navigation decisions and maintain proper course alignment.

In summary, the Horizontal Situation Indicator (HSI) is a navigational instrument used in aircraft to provide pilots with information about their horizontal position and orientation. It combines the functionality of a heading indicator and a course deviation indicator, making it an essential tool for navigation and situational awareness during flight.