What is Rate of climb?

In aeronautics, the rate of climb is an aircraft's vertical speed, that is the positive or negative rate of altitude change with respect to time. In most ICAO member countries, even in otherwise metric countries, this is usually expressed in feet per minute ; elsewhere, it is commonly expressed in metres per second. The RoC in an aircraft is indicated with a vertical speed indicator or instantaneous vertical speed indicator.

The temporal rate of decrease in altitude is referred to as the rate of descent or sink rate. A negative rate of climb corresponds to a positive rate of descent: RoD = −RoC.