causes of wake turbulence (copy)

Convective currents, mechanical disturbances, ____, and ___ are the four main causes of turbulence.

wind shear, wake turbulence

What are the 5 causes of wake turbulence?

• Wing-tip vortices

• Rotor-tip vortices

• Jet engine thrust stream (or Jet blast)

• Rotor downwash

• Prop wash

What are the 4 forces acting on a flying aircraft?

Drag, lift, push or pull, weight

Lift is generated by _____ underneath a wing; this _____ lifts the wing

higher pressure, pressure

Wake turbulence via wing-tip vortices is created as the air flows ____ from the _____

outward, body to the wingtip

When air reaches the wingtip, the high pressure _____ towards low pressure, resulting in a twisting vortex of air that continues ______

rotates, in a downward spiral

The strength of wing-tip vortices is governed by _____ and the _____ of an aircraft

shape of the wings, weight and speed

Wing-tip vortices are most pronounced at _____

the wing-tips

Wing-tip vortices show little dissipation within the first _____ of being produced. After ____, the dissipation rate will vary depending on factors.

2 minutes

Wing-tip vortices on each side are ______ and ______ in shape.

counter-rotating, cylindrical

Wing-tip vortices rotate _____ from the left-hand wing and _____ from the right-hand wing

clockwise, counter-clockwise

Rotor-tip vortices are caused by the ______ of the blades and _______ to create intense, complex wake vortices

wing-like shape, rotation and forward motion

Problems created by rotor-tip vortices are ______ than fixed-wing aircraft

generally greater

The increased problems from rotor-tip vortices are because the helicopter’s lower operating speeds produce ________; the ______ has little bearing.

higher intensity wakes, size of the aircraft

________ helicopters produce high-velocity vortices similar to wing-tip vortices

Departing or landing

A jet engine thrust stream is the ______ created behind an aircraft’s jet stream

area of turbulence

The wake turbulence from jet engine thrust stream is usually _____, but ______ and more dangerous the _____ you are to the aircraft.

extreme, relatively short, closer

The jet wash/blast is greatest when power is increased to move the aircraft forward ______.

from a stopped position

What is the jet blast intensity within 45 metres of the jet?

120 km/h

Rotor downwash is the _____ created by helicopters ______.

downward turbulence, hovering or in forward flight

The strength of rotor downwash depends on:

• Helicopter weight

• Air density

• Forward speed

• Rotor length

Rotor downwash is greatest in ______ because _____.

hovering flight, airspeed is practically 0

Once rotor downwash reaches the ground, it spreads out in all directions, causing _____.

severe buffetting

Prop wash is turbulence created by _____

any propeller-driven aircraft

Prop wash is based on the same principle as ______; but the effect is not as great

jet engine thrust stream

Turbulence happens when the ____ under the wing meets the low pressure on top of the wing.

high pressure

Aircraft flying directly into the core of a vortex will tend to _____ with the vortex. This is called _____.

roll, induced roll

An aircraft’s capability to counteract an induced roll depends on its _____ and _____.

wingspan, responsiveness

The smaller the aircraft that follows into the vortex in relation to the preceding aircraft that created it, the _______ and the _____ the following aircraft is to correct the uncommanded action.

more pronounced the effect, less likely

When the ____ and ____ of a larger aircraft extend beyond the vortex, counter-roll control is usually effective and the effect of the induced roll can be minimized.

wingspan, ailerons

Wing-tip vortices that are generated behind ______, or aircraft that descent to less than ______ above the runway, are subject to _____.

departing or arriving aircraft, 100 feet, ground effect

In a no-wind situation, vortices that contact the ground tend to move ______, at a speed of about _____.

laterally outward, 5 knots

A crosswind can move wing-tip vortices sideways with _____, which can increase or decrease respective vortices depending on their ____.

the direction of the wind, rotation

A _____ or _____ can also change where the vortices begin or end in relation to the runway.

tailwind, headwind

In calm or light wind conditions, wing-tip vortices can:

• Remain in the touchdown area

• Drift from aircraft operating on a nearby runway

• Sink into take-off or landing paths from a crossing runway

• Sink into the traffic pattern from other runway operations

• Sink into the flight path of VFR flights at 500 feet AGL and below

In calm and light wind conditions, wing-tip vortices can sink into the flight path of VFR flights at ______ and below.

500 feet AGL

Which of these factors contributes to the strength of a wing-tip vortex?

All of these

When is rotor downwash greatest?

When airspeed is low