At what speed do the vortices of a departing large aircraft typically move laterally over the ground?

The vortices created by a departing large aircraft typically move laterally over the ground at a speed range of about 2 to 3 knots. This speed is significant because understanding the movement of these vortices is crucial for ensuring safety during ground operations, particularly for smaller aircraft taking off or landing in proximity to larger ones.

Vortices are generated by the wings of an aircraft as they create lift, resulting in a spiraled flow of air that trails from the wingtip. After takeoff, these vortices can drift laterally due to environmental conditions such as wind, and their speed can be influenced by a variety of factors including aircraft weight, atmospheric conditions, and wind speed.

The choice of 2 to 3 knots is based on an average scenario under standard conditions, and knowing this allows pilots and ground crew to appropriately manage the risk of wake turbulence. These vortices can pose a risk for other aircraft, thus identifying their movement speed is an essential part of flight safety protocols.