The Vertical Speed Indicator (VSI)

What is a VSI ?

VSI
This is vertical speed indicator from a typical light helicopter, in this case the Hughes / Schweizer 300.
It displays rate of climb or descent by moving a needle around the instrument face.
The needle is deflected upwards (clockwise) to indicate a climb, and downwards (anticlockwise) to indicate a descent.
The numbers around the scale are hundreds of feet per minute, and each graduation on the scale is one hundred feet per minute.
Autopilot VSI

How does it work ?

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