Wake Turbulence

M10

What is wake turbulence?

the phenomenon resulting from the passage of an aircraft through the atmosphere

What are vortices?

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

Vortices from what three types of aircrafts cause high velocity and are hazardous to smaller aircrafts?

Large, Heavy, Super Aircrafts

What three factors determine the strength of a vortex?

Weight, Shape of wing, & Speed of Aircraft

When is the greatest vortex strength generated?

Heavy, Clean , and Slow

Strength of vortices can diminish what?

time and distance

What does the term “clean” refer to?

Aircrafts configuration when it has its gears up, no flaps extended, or any other type of wing extensions.

What is the greatest factor that affects the intensity of wake turbulence?

Weight

What increases with the weight?

the strength of the wake turbulence

Do every airplane and helicopter generate wake turbulence?

Affirmative

How do the flaps effect wake turbulence?

When flaps are extended the intensity of wake turbulence can change.

What is clean configuration?

Flaps are NOT extended causing a smaller area and wing loading is greater per square foot.

What is Dirty configuration?

Flaps are extended disrupting air flow and the total Wing area increases while decreasing the wing loading.

What speed increases the chance of wake turbulence?

Slower Speed

What type of aircraft would cause greater wake turbulence? (i.e enroute, takeoff, approach)

An aircraft approaching an airport (its slowing down)

What are wingtip vortices?

Lift is generated by the creation of pressure differential over the wing surface.

Low pressure above the wing and High pressure below the wing

What are the two names for a swirling air mass produced off the wingtips trailing behind the aircraft?

Wake Vortex or Wingtip Vortices

When are vortices generated?

the moment the aircraft generates lift (normally when the nose leaves the ground)

When do vortices discontinue?

the moment the aircraft stops generating lift (normally when all landing gear has touched down)

What is the Vortex sink rate?

vortices from larger aircrafts sink approximately 300 to 500 feet per minute

When does the vortex sink rate level off?

500 to 1000 feet below the flight path

What two vortices actions occur with sink rate?

slowly move outward from their track

diminish in strength with time

What vortex movement occurs on the ground with no wind?

Vortices will move laterally from larger aircraft

2-3kt

Crosswinds of 1 to 5 watts can have what effect on runways?

The crosswinds cause one vortex to stay still while the other could be pushed onto a parallel runway

What is the problem with some tailwinds?

they can move vortices into the landing zone of aircraft that were originally trying to avoid wake turbulence

What is induced role?

the mechanical force a wake vortex has on an aircraft with no counter control (causes the aircraft to role immediately)

What is the hazard of wake turbulence?

Could cause inflight structural damage of catastrophic proportions

Induced roll exceeds roll control using aircraft to roll

What must be given to heavier aircrafts with smaller aircrafts in trail?

Larger separation

What is vortex roll?

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

Wingspan

counter control capability

Vortex role is based on what?

The wingspan of an aircraft

The counter control capability of the aircraft

What is counter control?

An aircraft with a larger wingspan that extends beyond the outer edges of a vortex is better able to counter the roll effects of the vortex compared to a smaller aircraft whose wings do not.

A helicopter will generate a downwash from its main rotors when?

In a slow taxi or hover

Downwash vortices spread outward how far?

3 times the diameter of the rotor

Downwash circulation occurs in what direction?

ALL directions

When in forward flight what type of vortices do helicopters generate?

a pair of wingtip vortices

What is Jet blast?

is jet engine exhaust (thrust stream turbulence)

When is jet blast normally experienced?

during ground operations and during initial takeoff roll prior to lift

Are controllers responsible for anticipating wake turbulence?

Negative, because it is unpredictable

What is used in lieu of “wake turbulence”?

jet blast

prop wash

rotor wash

What is the greatest impact wake turbulence has on ATC?

Increased Separation for

Tower operations (ground and airborne)

Radar operations (approach and enroute)

What causes lower airport acceptance rate?

Delays caused by increased separation