Wingtip vortices are greatest when the generating aircraft is described as which configuration?

• A. Light, dirty, and fast
• B. Heavy, clean, and slow
• C. Heavy, dirty, and fast
• D. Light, clean, and slow

Answer: (B)

Wingtip vortices are formed by the wing’s lift, with their strength tied directly to how much lift the wing is producing. Heavier aircraft must generate more lift, so they shed more energy into the wake. Flying slower at a given weight requires a higher lift coefficient to stay aloft, which increases the lift and the resulting vortices. A clean configuration (flaps retracted, gear up) keeps lift concentrated on the wing itself, without the extra lift devices that can alter lift distribution and generally reduce the intensity of the main wingtip vortices. In contrast, extending flaps or flying faster reduces the lift effectiveness or changes the lift distribution in a way that weakens the primary vortices behind the wingtips. Putting these together, the strongest wingtip vortices occur when the aircraft is heavy, in a clean configuration, and flown slowly.