A CFII explains to an instrument student the primary advantage of a Horizontal Situation Indicator (HSI) over a separate heading indicator and VOR/localizer CDI. Which statement best describes this advantage?
- AThe HSI automatically corrects for all VOR station errors without pilot input
- BThe HSI combines a gyro-stabilized heading display with course deviation information into a single instrument, improving situational awareness
- CThe HSI eliminates the need for the pilot to ever cross-check the magnetic compass
- DThe HSI replaces the need for glide slope indications on an ILS approach
Show answer & explanationAnswer & explanation
Correct answer: B. The HSI combines a gyro-stabilized heading display with course deviation information into a single instrument, improving situational awareness
The HSI integrates the heading indicator's rotating compass card with a course deviation indicator (CDI) needle and course selector, allowing the pilot to see aircraft heading and course guidance in a single, intuitively oriented display, which significantly improves situational awareness compared to cross-referencing separate instruments.
Why the other options are wrong
- A. The HSI does not correct VOR signal errors; it only displays what the receiver provides.
- C. The compass is still periodically needed to check the heading indicator/HSI for precession error.
- D. Most HSIs do display glide slope deviation, but it is a separate additional feature, not a replacement function.
Horizontal Situation Indicator (HSI)
A combined navigation instrument that integrates a gyro-stabilized heading indicator with a course deviation indicator and course selector, providing an intuitive picture of aircraft position relative to a selected course.
- Combines heading indicator and CDI into one display
- Includes course selector (OBS) and TO/FROM indication
- Many HSIs also display glide slope deviation for ILS approaches
Memory trick: HSI = heading and course guidance married into one happy display