In all stages of flight, the performance of the aircraft is a combination of the power setting and nose attitude selected.
To fly straight and level at a chosen airspeed and weight, the pilot applies the appropriate power setting and selects the required nose attitude.
To climb at Vx or Vy, the correct power setting is applied (typically full power in training aircraft) and the Vx or Vy speed is achieved by selecting the appropriate nose attitude.
To commence a descent, a power setting for the desired descent angle or rate is chosen and the nose attitude is adjusted to control airspeed.
This process is often summarised as: