When does an aircraft's wake begin?

An aircraft's wake begins at rotation. This is the moment when the aircraft's nose is lifted off the ground during takeoff, causing the wings to start generating lift. At this stage, the airflow around the aircraft is significantly altered as the lift begins to create turbulence and vortices at the wingtips, which comprise the wake.

Understanding that the wake is closely tied to the lift production and airflow dynamics is crucial. It's important to note that simply starting the takeoff roll or retracting flaps does not yet initiate the lift necessary for the creation of wake turbulence. Similarly, while lift-off is a key phase, the wake itself is defined as beginning with the rotation because that is when the wings start to actively generate lift and the associated turbulence patterns are formed.