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BFS - Meteorology > C09 - Turbulence and Windshear > Flashcards

C09 - Turbulence and Windshear Flashcards

1
Q

Define Turbulence?

A

Sudden changes in wind velocity.

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2
Q

Define Windshear?

A

Substantial changes in wind velocity both vertical and horizontal.

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3
Q

What affect does Turbulence have on an Aircraft?

A

The Attitude.

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4
Q

What affect does Windshear have on an Aircraft?

A

Displace from current flight path.

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5
Q

What are the three intensity terms used to describe Turbulence and their speed in knots?

A
  • Light = 5-15kt.
  • Moderate = 15-25kt.
  • Severe = >25kt.
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6
Q

During which type of Turbulence are passengers required to wear seat belts?

A

Moderate and Severe.

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7
Q

During which type of Turbulence can food service no longer be conducted in?

A

Severe.

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8
Q

Name two types of Turbulence?

A
  • Mechanical.

- Thermal.

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9
Q

What causes Mechanical Turbulence?

A

Physical obstructions.

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10
Q

What is the Reported Turbulence over the Sea at <15kt, 15-30kt and >30kt (3)?

A
  • Light.
  • Moderate.
  • Moderate/Severe.
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11
Q

What is the Reported Turbulence over the Plains at <15kt, 15-30kt and >30kt (3)?

A
  • Only Light.
  • Moderate.
  • Severe.
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12
Q

What is the Reported Turbulence over Broken Terrain at <15kt, 15-30kt and >30kt (3)?

A
  • Light/Moderate.
  • Severe.
  • Extreme.
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13
Q

What causes Thermal Turbulence?

A

Air rising due to surface heating.

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14
Q

When is Thermal Turbulence most likely to occur?

A

During warm days with clear skies.

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15
Q

How are Low-Level Turbulence caused by?

A

Interactions between Wind and the Earth’s Surface.

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16
Q

What is the name given to the layer which the surface influences the air flow?

A

Friction Layer.

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17
Q

What type of Airflow is found above the Friction Layer?

A

Laminar.

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18
Q

What is above the Friction Layer?

A

Friction Level.

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19
Q

The ‘____’ the Thermal Activity, the ‘____’ the Mechanical Disturbance, the higher the Friction Level (2)?

A
  • Greater.

- Greater.

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20
Q

On a hot day, how high above the surface can the Friction Level be?

A

1 km / 3,000 ft.

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21
Q

Define Mountain Waves?

A

Turbulent waves of Air which can form above or downwind of a Mountain Range.

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22
Q

How far can Mountain Waves extend downwind and upwards to the Tropopause?

A

50-100 NM.

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23
Q

The movement of air in Mountain Waves can exceed ‘____’?

A

2,000 ft per minute.

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24
Q

Wind Speed at Mountain Height is ‘____’ and increases with Height?

A

15-20kt.

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25
Q

Wind Direction of Mountain Waves are ‘____’ perpendicular of Mountains?

A

30°.

26
Q

In Mountain Waves, a region of ‘____’ can be found at the Mountain Top with less stable air ‘____’ and ‘____’ (3)?

A
  • Stability.
  • Above.
  • Below.
27
Q

Where can you find Severe Turbulence in Mountain Waves?

A

The Rotor Zone.

28
Q

What visual warning sign can be seen in the Rotor Zone?

A

Roll Clouds.

29
Q

Where can you find the most powerful Turbulence in the Rotor Zone?

A

Beneath the first wave.

30
Q

Which cloud can act as a visual warning sign to Standing Waves?

A

Lenticular.

31
Q

Which type of cloud hugs the side and top of a ridge, to indicate the presences of Standing Waves?

A

Cap Clouds.

32
Q

When can Low Altitude Windshear become dangerous in Flight (2)?

A
  • Final Approach.

- Take-off.

33
Q

How is Vertical Windshear measured?

A

Knots per 100 ft.

34
Q

How is Horizontal Windshear measured?

A

Knots per 1,000 ft.

35
Q

What speeds can Updraught and Downdraught be found in Thunderstorms?

A

10,000 ft per minute.

36
Q

What is the countermeasure against Windshear?

A

Avoid them completely.

37
Q

Name four causes of Windshear?

A
  • Thunderstorms.
  • Frontal Passage.
  • Inversions.
  • Topographical.
38
Q

True or False. Thunderstorms cause the most severe Windshear?

A

True.

39
Q

Other than Windshear, what other phenomenon are associated with Thunderstorms (3)?

A
  • Severe Turbulence.
  • Lightning.
  • Hail.
40
Q

Define Frontal Passage?

A

Boundaries between two different Air Mass.

41
Q

What carries the risk of Windshear in Frontal Passage?

A

Temperature.

42
Q

By how much change in Temperature can be associated with Frontal Passage?

A

> 5°C.

43
Q

How fast can a Frontal Movement exceed?

A

> 30kt.

44
Q

Which type of Front poses more risk?

A

Cold Front.

45
Q

Define Inversions?

A

Can form at Low-Level, especially at night in a High Pressure System.

46
Q

An Inversion warning is issued if the Temperature changes by more than ‘____’ between ground-level and ‘____’ (2)?

A
  • 10°C.

- 1,000 ft.

47
Q

Define Topographical Windshear?

A

Windshear created by natural or artificial features.

48
Q

True or False. Wind blowing between two buildings, hills and along a valley can change direction and increase speed?

A

True.

49
Q

Where can Down Draughts be found?

A

In, above or below Thunderstorms.

50
Q

In a Down Draught, currents of Air can change what two factors of an Aircraft in Flight?

A
  • Airspeed.

- Wing’s Angle of Attack.

51
Q

During an Updraught an Aircraft will?

A

Climb.

52
Q

During a Downdraught an Aircraft will?

A

Sink.

53
Q

Define Microbursts?

A

Associated with intense Thunderstorms and includes all forms of Windshear?

54
Q

What should a Pilot do if Microburst activity is found in the vicinity of the Aerodrome?

A

Abort Approach / Delay Take-off.

55
Q

What should a Pilot do if you encounter an area of intense precipitation ahead of you on Final Approach?

A

Initiate a Go-Around.

56
Q

Define Jet Stream?

A

Very long narrow bands of fast moving air just beneath the Tropopause.

57
Q

What kind of Turbulence is created from Jet Streams?

A

Clear Air Turbulence.

58
Q

The highest change of speed occurs on the side of the Jet Stream adjacent to the ‘____’?

A

Cold Air.

59
Q

What countermeasures should be used where on Final Approach with expected Windshear (4)?

A
  • Increase Power.
  • Raise the Nose.
  • Co-ordinate Pitch and Power.
  • Prepare for Missed Approach.
60
Q

What countermeasures should be used where on Take-off with expected Windshear (4)?

A
  • Recognise Threat quickly and commit to appropriate action.
  • Follow Operations/Aircraft Flight Manual Techniques.
  • Use Maximum Power.
  • Adopt appropriate pitch angle and hold. Do Not chase the Airspeed.
61
Q

What is the most sensible course of action with expected Windshear during Final Approach?

A

Delay Landing / Divert to alternative Airport.

62
Q

What is the most sensible course of action with expected Windshear during Take-off?

A

Delay Take-off until Windshear has diminished.

BFS - Meteorology (22 decks)

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