Reverse sensing occurs on the back course using standard VOR equipment. With a horizontal situation indicator (HSI) system, reverse sensing is eliminated if it is set appropriately to the front course.

What is the difference between a standard VOR and HSI?

On a conventional VOR indicator, left–right and to–from must be interpreted in the context of the selected course. When an HSI is tuned to a VOR station, left and right always mean left and right and TO/FROM is indicated by a simple triangular arrowhead pointing to the VOR.

What is the difference between HSI and CDI?

Whereas a traditional CDI will only show your deviation to a given VOR radial, an HSI will show both your present heading and lateral position in relation to a VOR radial or GPS course line and doesn’t have the potential for reverse sensing.