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Most of the factors affecting hover and takeoff performance also affect climb performance. In addition, turbulent air, pilot techniques, and overall condition of the helicopter can cause climb performance to vary. 

A helicopter flown at the best rate-of-climb speed (V$_{Y}$) obtains the greatest gain in altitude over a given period of time. This 

speed is normally used during the climb after all obstacles have been cleared and is usually maintained until reaching cruise altitude. Rate of climb must not be confused with angle of climb. Angle of climb is a function of altitude gained over a given distance. The V$_{Y }$results in the highest climb rate, but not the steepest climb angle, and may not be sufficient to clear obstructions. The best angle of climb speed (V$_{X}$) depends upon the power available. If there is a surplus of power available, 

