Wind Shear and Turbulence

Question 1

What is turbulence?

Answer 1

• A general term relating to any kind of irregular and often unpredictable air flow that can upset the intended flight path or performance of an aircraft.

Question 2

What is wind shear?

Answer 2

• Created when two adjacent air masses travelling in difference directions and/or speeds intersect with each other.
• Friction between these two air masses as they intersect can cause turbulent or irregular air flow.

Question 3

What is the difference between horizontal and vertical wind shear?

Answer 3

• Vertical windshear is windshear that occurs at different altitudes.
• Horizontal windshear is windshear that occurs at the same level.

Question 4

What is undershoot shear?

Answer 4

Sudden decrease in the headwind component for an aircraft landing, causing it to drop below the target glide path and to land short of the runway.

Question 5

What is an overshoot shear?

Answer 5

Sudden increase in the headwind component that may cause an aircraft to fly above the glide path and land long.

Question 6

What may be an indication of windshear conditions when your aircraft is flying?

Answer 6

• Airspeed fluctuations of 15 kts

- Vertical speed changes of 500 FPM or more can indicate potential wind shear conditions

Question 7

What is mechanical turbulence?

Answer 7

• Mechanical turbulence occurs when frictional forces interact with surface winds to cause turbulence eddies.

Question 8

What is orographic turbulence?

Answer 8

• Created by large scale displacement of airflow by vertical features such as mountain ranges, hills or islands.

Question 9

What should be done to avoid orographic turbulence?

Answer 9

1. Fly on upwind side of mountains
2. Avoid approaching a mountain ridge from the less-side perpendicular to the ridgeline. Approach at 45 degrees
3. Monitor for pressure altimeter errors and consider adding additional safety altitude if IMC or at night.

Question 10

What is frontal zone turbulence?

Answer 10

Turbulence associated with movement of air across a front.

Question 11

What should be done when flying through a cold front?

Answer 11

Fly the path that will minimize the transit time across the front.

Question 12

Even though it is hard to detect, what type of cloud can be an indication of CAT?

Answer 12

Cirrus

Question 13

What is CAT often associated with?

Answer 13

1. The tropopause
2. High altitude jet streams
3. High altitude lows or troughs

Question 14

What can you do to avoid CAT?

Answer 14

Descend towards the warm (Equator) side

Question 15

What type of wind will hold wake turbulence over the runway?

Answer 15

Slight crosswind with slight quartering tailwind component.

Question 16

On TO and LDG, what should you do to avoid wake turbulence?

Answer 16

• On TO, get airborne before the rotation point of the heavier aircraft ahead and climb above their flight path.
• During landing, fly a steeper approach path and look to touchdown beyond the touchdown point of the aircraft landing ahead.

Question 17

What should a pilot do if they encounter moderate or severe turbulence?

Answer 17

Advise ATC and/or other pilots.

Question 18

What are the four classifications of turbulence?

Answer 18

1. Light
2. Moderate
3. Severe
4. Extreme

Question 19

What should be done when flying through turbulence?

Answer 19

• Reduce to turbulence penetration speed.
• Attempt to hold ATTITUDE rather than altitude
• Look to ride it out with minimum control movements.