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100 Cards in this Set
- Front
- Back
The primary cause of all changes in the earth's weather is
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Variation of solar energy received by the earth's regions
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Which force, in the northern Hemisphere, acts at a right angle to the wind and deflects it to the right until parallel to the isobars
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Coriolis
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What relationship exists between the winds at 2,000 feet above the surface and the surface winds
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The winds at 2,000 feet tend to parallel the isobars while the surface winds cross the isobars at an angle toward lower pressure and are weaker
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winds at 5,000 feet AGL on a particular flight are southwesterly while most of the surface winds are southernly. This difference in direction is primarily
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friction between the wind and the surface
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What causes surface winds to flow across the isobars at an angle rather than parallel to the isobars
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Surface friction
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An air mass is a body of air that
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Covers an extensive area and has fairly uniform properties of temperature and moisture.
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A characteristic of the stratosphere is
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relatively small changes in temperature with an increase in altitude
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A jet stream is defined as wind of
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50 knots or greater
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The average height of the troposphere in the middle latitudes is
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37,000 feet
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The strength and location of the jet stream is normally
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weaker and farther north in the summer
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Which feature is associated with the tropopause
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abrupt change in temperature lapse rate
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Which weather phenomenon is always associated with the passage of a frontal system
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a wind change
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Which is a characteristic of a low-level wind shear as it relates to frontal activity
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with a warm front, the most critical period is before the front passes the airport
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Frontal waves normally form on
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slow moving cold fronts or stationary fronts
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Where do squall lines most often develop
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ahead of a cold front
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Which are characteristics of an unstable cold air mass moving over a warm surface
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Cumuliform clouds, turbulence, and good visibility
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What are characteristics of stable air
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poor visibility, steady precipitation, and stratus-type clouds
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What type clouds can be expected when an unstable air mass is forced to ascend a mountain slope
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clouds with extensive vertical development
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Which is a characteristic of stable air
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stratiform clouds
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the general characteristics of unstable air are
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good visibility, showery precipitation, and cumuliform-type clouds
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What type of clouds will be formed if very stable moist air is forced up slope
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stratified clouds with little vertical development
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steady precipitation, in contrast to showers, preceding a front is an indication of
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stratiform clouds with little or no turbulence
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what enhances the growth rate of precipitation
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upward currents
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Which of the following combinations of weather producing variables would likely result in cumiliform-type clouds, good visibility,rain showers, and possible clear-type icing in clouds
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unstable, moist air and orographic lifting
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What determines the structure or type of clouds which form as a result of air being forced to ascend
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the stability of the air before lifting occurs
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Stability can be determined from which , measurement of the atmosphere
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ambient lapse rate
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what are some characteristics of unstable air
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turbulence and good surface visibility
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Unsaturated air flowing up slope will cool at the rate of approximately (dry adiabatic rate)
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3' per 1,000 feet
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what feature is associated with a temperature inversion
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a stable layer of air
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which weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high
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smooth air and poor visibility due to fog, haze, or low clouds
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a temperature inversion will normally form only
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in stable air
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A common type of ground or surface based temperature inversion is that which is produced by
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ground radiation on clear, cool nights when the wind is light
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which conditions are favorable for the formation of radiation fog
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Clear sky, little or no wind, small temperature/dew point spread, and over a land surface
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What situation is most conducive to the formation of radiation fog
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warm, moist air over low, flatland areas on clear, calm nights
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The most frequent type of ground-or surface-based temperature inversion is that produced by
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radiation on a clear,relatively still night
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what types of fog depend upon wind in order to exist
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advection fog and upslope fog
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In what localities is advection fog most likely to occur
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coastal areas
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In which situation is advection fog most likely to form
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an air mass moving inland from the coast in winter
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Fog is usually prevalent in industrial areas because of
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an abundance of condensation nuclei from combustion products
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Which weather condition can be expected when moist air flows from relatively warm surface to a colder surface
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fog
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Under which condition does advection fog usually form
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moist air moving over colder ground or water
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the amount of water vapor which air can hold largely depends on
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air temperature
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Clouds, fog, or dew will always form when
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water vapor condenses
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To which meteorological condition does the term "dew point' refer
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the temperature to which air must be cooled to become saturated
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which conditions result in the formation of frost
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Temperature of the collecting surface is below the dewpoint of surrounding air and the dewpoint is colder than freezing
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what are the 4 families of clouds
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high. middle, low, and those with extensive vertical development
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which family of clouds is least likely to contribute to structural icing on an aircraft
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high clouds
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the presence of standing lenticular altocumulus clouds is a good indication of
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very strong turbulence
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the suffix "nimbus", used in naming clouds means a
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rain cloud
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Standing lenticular clouds, in mountainous areas, indicate
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turbulence
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which clouds have the greatest turbulence
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cumulonimbus
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a high cloud is composed mostly of
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ice crystals
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Fair weather cumulus clouds often indicate
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turbulence at and below the cloud level
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when is an airplane most likely to be struck by lightning
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OAT between-5'C and +5'C
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What are the requirements for the formation of a thunderstorm
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sufficient moisture, an unstable lapse rate, and lifting action
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what is an indication that downdrafts have developed and the thunderstorm cell has entered the mature stage
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precipitation begins to fall from the cloud base
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Which procedure is recommended if a pilot should unintentionally penetrate embedded thunderstorm activity
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set power for recommend turbulence penetration airspeed and attempt to maintain a level flight attitude
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which thunderstorms generally produce the most severe conditions, such as heavy hail and destructive winds
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squall line
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which weather phenomenon is always associate with a thunderstorm
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lightning
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During the life cycle of a thunderstorm, which stage is characterized predominantly by downdrafts
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dissipating
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If squall lines are reported at your destination, what wind conditions should you anticipate
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sudden increases in wind speed of at least 16 knots rising to 22 knots or more, lasting for at least 1 minute
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What is indicated by the term "embedded thunderstorm"?
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thunderstorms are obscured by massive cloud layers and cannot be seen
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Which weather phenomenon signals the beginning of the mature stage of a thunderstorm
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the start of rain at the surface
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Which is true regarding the use of airborne weather-avoidance radar for the recognition of certain weather conditions
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the radarscope provides no assurance of avoiding instrument weather conditions
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In which meteorological environmental is aircraft structural icing most likely to have the highest rate of accumulation
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freezing rain
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Test data indicate that ice, snow, or frost having thickness and roughness similar to medium or coarse sandpaper on the leading edge and upper surface of an airfoil can
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reduce lift by as much as 30 percent and increase drag by 40 percent
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which precipitation type normally indicates freezing rain at higher altitudes
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Ice pellets
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What is an operational consideration if you fly into rain which freezes on impact
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temperatures are above freezing at some higher altitude
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What temperature condition is indicated if wet snow is encountered at your flight altitude
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the temperature is above freezing at your altitude
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The presence of ice pellets at the surface is evidence that
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there is freezing rain at a higher altitude
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why is frost considered hazardous to flight operation
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frost causes early airflow separation resulting in loss of lift
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If the air temperature is +8'C at an elevation of 1,350 feet and a standard (average) temperature lapse rate exists, what will be the approximate freezing level
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5,350 feet MSL
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what happens to residual ice that remains after deice boots are inflated and shed ice
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residual ice increases with an decrease in airspeed or temperature
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The most susceptible surface of the aircraft for ice accumulation is the
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tailplane
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If you detect icing accumulation in flight, especially if the aircraft is not equipped with deicing system, you should
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leave the area of precipitation, if able, or fly to an altitude where the temperature is above freezing
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when conditions favoring the formation of ice are present, pilots should check for ice accumulation prior to flight. The best way to do this by
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using a flashlight and watching for light reflection
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To recover from a tailplane stall brought on by ice accumulation, the pilot should
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retract the flaps and increase power, but only to compensate for the reduction in lift
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Tailplane icing can be detected by A(N)
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sudden uncommanded nose-down pitch
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Tailplane icing can be detected by
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elevator control pulsing, oscillations or vibrations
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In an aircraft equipped with a pneumatic deicing system, the appropriate technique for removing ice is to
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operate the pneumatic deicing system several times
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a tailplane stall as the result of ice accumulation is most likely to occur during
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approach and landing
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with regards to landing, which is true
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heavy icing on the leading edge is not as bad as light icing on the upper surface
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should you experience uncommanded roll due to icing forward of the ailerons, the most appropriate response is to
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reduce the angle of attack by increasing airspeed or extending flaps to the first setting
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should you experience buffeting or vibrations after extending the flaps upon exiting or during icing conditions, the most likely reason is
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Incipient tailplane stall
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the best technique for using deicing boots is to
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use them immediately upon visual detection of any ice
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How should deicing boots be used after exiting flight in icing conditions
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you should continue to cycle the boots several times to remove residual ice left behind after normal boot operation
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What is an important characteristic of wind shear?
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It is an atmospheric conditions that may be associated with a low-level temperature inversion, a jet stream, or frontal zone
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A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as
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light turbulence
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what is an important characteristic of wind shear
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it may be associated with either a wind shift or a wind speed gradient at any level in the atmospeher
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where can wind shear associated with a thunderstorm be found? Choose the most complete answer
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On all sides of the thunderstorm cell and directly under the cell
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where does wind shear occur
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with either a wind shift or wind speed gradient at any level in the atmosphere
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Hazardous wind shear is commonly encountered near the ground
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during periods of strong temperature inversion and near thunderstorms
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an aircraft that encounters a headwind of 45 knots, within a microburst, may expect a total shear across the microburst of
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90 knots
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Maximum downdrafts in a microburts encounter may be a strong as
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6,000 feet per minute
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what is the expected duration of an individual microburst
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seldom longer than 15 minutes from the time the burst strikes the ground until dissipation
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(Refer to figure 13 on page 302) the aircraft in position 3 will experience which effect in a microburst encounter
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strong downdraft
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(Refer to figure 13 on page 302) when penetrating a microburst, which aircraft will experience an increase in performance without a change in pitch or power
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1
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(Refer to figure 13 below) How will the aircraft in position 4 be affected by a microburst encounter
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performance decreasing with a tailwind and downdraft
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(Refer to figure 13 below) If involved in a microburst encounter, in which aircraft positions will the most severe downdraft occur
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3 and 4
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(Refer to figure 13 below) what effect will a microburst encounter have uponn the aircraft in position 4
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strong tailwind
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