Wiktionary
n. (context aviation English) The rate at which an aircraft gains altitude. A negative rate of climb implies descent.
Wikipedia
In aeronautics, the rate of climb (RoC) is an aircraft's vertical speed – the 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 (ft/min). Elsewhere, it is commonly expressed in metre per second (m/s). The rate of climb in an aircraft is indicated with a vertical speed indicator (VSI) or instantaneous vertical speed indicator (IVSI).
The rate of decrease in altitude is referred to as the rate of descent or sink rate. A decrease in altitude corresponds with a negative rate of climb.
Usage examples of "rate of climb".
I split up right between the two of them, their rate of closure dangerously high, and my rate of climb too slow.
In this case of the tarn one's very life can depend on such things as understanding its speed, its rate of climb, the sharpness of its turns, and so on.
He was immediately on the turn and slip, glancing at the altimeter to make sure he kept a positive rate of climb.
The chronically slow rate of climb suddenly changed as something seemed to give the vessel a hearty shove in the rear.
Tako noticed in the background of the plateau a few Springer ships taking off at a steep rate of climb in a westerly direction where the big spaceport was situated.
The rate of climb could best be described as slow, but the ship remained stable in flight and moved upward at a steady pace.
The VVI wasn't working properly, though, as it showed first no climb, then a dive, then an impossible 4000 feet per minute rate of climb.
Still it climbed slowly, unbelievably slowly, it seemed that it must topple over at any moment, then at 150 feet another violent explosion as the second set of fuel cylinders ignited, the Shrike doubled its rate of climb, a third explosion about 600 feet and then it began to accelerate at fantastic speed.