Definition
An electronic cockpit display that shows the aircraft's heading, course, and navigation information on a single screen, replacing the traditional mechanical horizontal situation indicator. It typically presents a compass rose, course deviation indicator, bearing pointers, and selected navigation source, and is integrated into a primary flight display or multifunction display in a glass cockpit.
Plain English
A digital screen that shows you which way the aircraft is pointed, the course you've selected, and how well you're tracking it — all in one picture.
Context Anchor
Seen in glass-cockpit airplanes during navigation, instrument flying, and automation management, especially when checking what course or navigation source the display is using.
Derivation
The 'e' stands for electronic, distinguishing it from the older mechanical HSI. The HSI itself was developed to combine the heading indicator and course deviation indicator into one instrument, reducing scan workload.
Why Pilots Care
Reduces pilot workload by consolidating heading, course, and deviation information into one easily scanned display, supporting better situational awareness during instrument flight.
Intuition Check
Do not think of the e-HSI as the system that navigates the airplane by itself. It is a display that shows selected navigation information so the pilot can manage and verify it.
Example Sentence 1
After selecting the GPS as the navigation source, the pilot watched the course needle on the e-HSI center as the aircraft intercepted the desired track.
Example Sentence 2
During the arrival, the e-HSI showed the waypoint sequence while the autopilot remained coupled to the flight plan.