In terms of vortex strength, when is it weakest regarding an aircraft's flight conditions?

The strength of wake turbulence, also referred to as vortex strength, is primarily influenced by the weight and speed of the generating aircraft. When an aircraft is at low speed, particularly during phases like low-speed flight or approach, the vortices produced are less energetic compared to those generated at higher speeds.

During takeoff, although the aircraft is growing in speed and generating some turbulence, it is still primarily in the initial climb phase where its speed isn’t yet sufficient to create strong vortices. In contrast, shortly after landing, the aircraft has likely reached a lower power setting and could be in a configuration that still generates substantial wake disturbances.

At cruising altitude, the aircraft is usually at a higher speed and at maximum weight, leading to stronger vortices. Therefore, when the aircraft is operating at low speed, it does not produce the same intensity of vortices as it would at higher speeds, making this condition the time of weakest vortex strength.