Climb, Best Angle of

Best angle of climb (V_X) is the airspeed that produces the maximum altitude gain per unit of horizontal distance traveled. It is used when obstacle clearance is the primary concern — for example, when trees or terrain require the aircraft to gain the most altitude in the shortest ground distance after take-off.

V_X vs. V_Y

V_X is always slower than V_Y. At V_X, the aircraft climbs at a steeper angle but slower rate of altitude gain per unit of time. At V_Y, the aircraft climbs faster but at a shallower angle. Use V_X for obstacle clearance; use V_Y once clear of obstacles for efficient climb to altitude.

Engine Temperatures at V_X

V_X is a slow airspeed — airflow over the engine is reduced and cooling is less efficient. Sustained climbs at V_X with full power can lead to elevated CHT and oil temperatures. Monitor engine gauges closely and transition to V_Y as soon as obstacles are cleared.

Related Terms

See also: Best Rate of Climb (V_Y), Climb-out.