ATC Wake Turbulence

Phenomenon resulting from the passage of an aircraft through the atmosphere

Wake Turbulence

Circular patterns of air created by the movement of an airfoil through the air when generating lift

Vortices

Strength of a vortex is governed by three factors:

• Weight of the generating aircraft

• Shape of the wing

• Speed of the generating aircraft

Greatest vortex strength is generated when the aircraft is

Heavy, Clean, and Slow

Strength of these vortices will diminish with

Time and Distance

Greatest factor that affects the intensity of wake turbulence

Weight

Intensity of the vortex can be changed when the flaps are

Extended

Wing configuration that allows for a stronger vortex

Clean configuration

Wing configuration that breaks down the formation of the vortex

Dirty configuration

Would an aircraft on approach or en route have a greater chance for wake turbulence

On approach

Generated by the creation of pressure differential over the wing surface

Lift

________ pressure above the wing, ________ pressure below the wing

Lowest, Highest

Circular patterns created by wake turbulence

• Wake vortex

• Wingtip Vortices

Vortex circulation off the wingtip is ________ off right wing, _______ off left

Counterclockwise, Clockwise

Because vortices have certain behavioral characteristics, pilots can:

• Visualize the wake location

• Take precautions to avoid it

When are vortices generated?

The moment the aircraft generated lift/rotation

Vortices from larger aircraft sink approximately

300 to 500 ft per minute

Vortices from larger aircraft will level off around

500 to 1,000 ft below the flight path

Under certain conditions, vortices may descend at a slower rate or may even climb slightly

• A temperature inversion may slow the decent

• Light updrafts may cause the vortices to climb

When close to the ground and there is zero wind, vortices from larger aircraft will move

• 2-3 knots laterally

• within 100 to 200 ft of the ground

mechanical force a wake vortex has on an aircraft with no counter control

Induced Roll

The ability of an aircraft to counteract the effects if the counteract the effects of the roll is based on

• wingspan of the aircraft

• counter control capability of the aircraft

Counter control is most effective and roll is minimal when the wingspan and the ailerons extend beyond the _______ of the vortex

outer edges

When does a helicopter generate a downwash

A slow hover taxi or a stationary hover

Downwash spreads to a distance of

approximately 3 times the diameter of the rotor

Helicopter will generate a pair of _______ when in ______ flight

Wingtip Vortices, forward

Jet blast is

Jet engine exhaust

Another word for Jet engine exhaust

Thrust stream turbulence

Jet blast is normally experiences during

Ground operations and during initial takeoff roll prior to life

Controllers may use the following terms in lieu of the term “wake turbulence”

• Jet Blast

• Prop Wash

• Rotor Wash

Wake turbulence has the greatest impact on ATC in areas of

Increased separation and traffic delays