The wake turbulence vortex strength is greatest when the aircraft is which combination?

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

Answer: (A)

Vortex strength comes from the lift the wing is producing. The more lift, the stronger the wake that trails behind a aircraft.

Being heavy means the wing has to generate more lift to support the weight, which increases the circulation around the wing and makes the vortices stronger. Flying slowly requires a higher angle of attack to generate the same lift, which further increases the lift coefficient and the energy in the trailing vortices. A clean configuration (flaps up, gear up) typically means the wing is producing lift in a straightforward, undisturbed way, allowing the wake to remain coherent and powerful rather than being disrupted by extended high-lift devices or gear.

So, when an aircraft is heavy, slow, and clean, the combination maximizes lift and maintains strong, persistent wake vortices, making that the condition associated with the strongest wake turbulence.