VY= Best Rate of climb speed all engines OP
VX= Best Angle of climb speed all engines OP
FROM FCTM A320
- Once airborne The speed can be selected on FCU to achieve the maximum RATE of climb or the maximum GRADIENT of climb.
- The speed to achieve the maximum RATE of Climb ie.To reach a given altitude in the SHORTEST TIME ,lies between ECON climb speed and Green Dot. As there is no indication of this speed on the PFD, a good rule of a thumb is to use TURBULENCE speed to achieve MAXIMUM RATE.
- The speed to achieve the maximum GRADIENT of climb , ie.To reach a given altitude in the SHORTEST DISTANCE, is GREEN DOT. The MCDU PERF CLB page displays the time and distance required to achieve the selected altitude by climbing at Green Dot speed. Avoid reducing to Green Dot speed at High altitude, particularly at heavy WT, as it can take a long time to accelerate to ECON mach