Which instrument would you use to determine the aircraft's lateral deviation from the course?

Which instrument would you use to determine the aircraft's lateral deviation from the course?

• A. HSI
• B. Altimeter
• C. Turn Coordinator
• D. Vertical Speed Indicator

Answer: (A)

Understanding how far you are from the path you intend to fly relies on a display that shows both the chosen course and your actual track, with a clear left-right cue. The horizontal situation indicator provides exactly this. It uses a course deviation indicator (CDI) to show how far off to the left or right you are from the selected course; when you’re on course the CDI is centered, and it deflects as you drift. The HSI combines the course information with the heading reference in one view, so you can quickly see where you need to steer to rejoin the line. The other instruments serve different purposes: the altimeter measures altitude, the vertical speed indicator shows climb or descent rate, and the turn coordinator indicates how rapidly you’re turning (rate of turn) and coordination, not your lateral position relative to a course.

Understanding how far you are from the path you intend to fly relies on a display that shows both the chosen course and your actual track, with a clear left-right cue. The horizontal situation indicator provides exactly this. It uses a course deviation indicator (CDI) to show how far off to the left or right you are from the selected course; when you’re on course the CDI is centered, and it deflects as you drift. The HSI combines the course information with the heading reference in one view, so you can quickly see where you need to steer to rejoin the line.

The other instruments serve different purposes: the altimeter measures altitude, the vertical speed indicator shows climb or descent rate, and the turn coordinator indicates how rapidly you’re turning (rate of turn) and coordination, not your lateral position relative to a course.