FAA Ground School Practice Test

What condition yields the greatest vortex strength in a generating aircraft?

1. When the aircraft is light and fast

2. When the aircraft is heavy, clean, and slow

3. When the aircraft is taking off

4. When the aircraft is landing

The correct answer is: When the aircraft is heavy, clean, and slow

The condition that yields the greatest vortex strength in a generating aircraft is when the aircraft is heavy, clean, and slow. This scenario is critical for understanding wake turbulence, which is generated by an aircraft as it moves through the air. When an aircraft is heavy, it creates more lift, which leads to stronger vortices. The term "clean" refers to the configuration of the aircraft; a clean aircraft typically has its flaps and landing gear retracted, reducing drag and allowing for more efficient airflow over the wings. This optimal airflow can further enhance the strength of the induced vortices. Lastly, a slower speed contributes to a higher angle of attack for the wings, which can result in more pronounced lift and, consequently, stronger vortex generation. This combination of factors makes wake turbulence a significant concern, especially during takeoff and landing phases. However, the greatest strength occurs not strictly during these operations but when the conditions described are met. Being aware of this condition helps pilots maintain safe distances from other aircraft to avoid the hazards associated with wake turbulence.