Vortices are generated at the moment the aircraft leaves the ground. Which option correctly completes the statement?

• A. leaves the ground
• B. begins taxi
• C. passes the takeoff roll
• D. touches down

Answer: (A)

Vortices arise whenever the wings are producing lift. As an aircraft goes through the takeoff sequence, lift increases and the wingtip vortices begin to form and roll up behind the airplane. The moment the aircraft actually leaves the ground marks the point when lift is being generated enough to start those vortices, so completing the statement with that moment makes sense.

During taxi, there’s little lift, so few or no vortices are created. After liftoff, vortices continue to exist but are not newly generated at a later moment unless lift is produced again. Touching down ends the lift-producing phase, so new vortices aren’t formed at that instant. This is why wake turbulence is a concern after takeoff, especially from heavier aircraft.