Final answer:
The Vertical Velocity Indicator (VVI) provides information about the rate of change of altitude during descent. A negative value indicates descent, a positive value indicates ascent, and zero means a constant altitude. The VVI value represents the rate of change in feet per minute.
Step-by-step explanation:
During descent, the Vertical Velocity Indicator (VVI) provides information about the rate of change of altitude. It indicates whether the aircraft is ascending or descending, and the rate at which it is doing so.
When the VVI shows a negative value, it means the aircraft is descending. The greater the negative value, the steeper the descent. Conversely, a positive value indicates an ascent. If the VVI is close to zero, it means the aircraft is maintaining a constant altitude.
For example, if the VVI reads -500 ft/min, it means the aircraft is descending at a rate of 500 feet per minute. If the VVI reads +1000 ft/min, it means the aircraft is ascending at a rate of 1000 feet per minute.