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Applying Human Factors Principles Additional Questions |
Meteorology6-1 What causes variations in altimeter settings between weather reporting points? A - Unequal heating of the Earth's surface. B - Variation of terrain elevation. C - Coriolis force. 6-1. Answer A. GFDPPM 6-7 (AW) Temperature changes cause variations in air pressure and density. Because the earth's surface is heated unevenly, altimeter settings will be different between weather stations. Answer (B) is wrong because altimeter settings are referenced to a standard datum, and elevation alone is not the cause of variations. Answer (C) is incorrect because Coriolis force deflects the circulation of air masses, but does not directly cause variations in altimeter settings.
6-2 The wind at 5,000 feet AGL is southwesterly while the surface wind is southerly. This difference in direction is primarily due to A - stronger pressure gradient at higher altitudes. B - friction between the wind and the surface. C - stronger Coriolis force at the surface. 6-2. Answer B. GFDPPM 6-9 (AW) Above 2,000 feet AGL, wind
flows along isobars. Below that altitude, friction with the earth's surface
deflects the wind. Answer (A) is wrong because the pressure gradient is not
always stronger at higher altitudes. Answer (C) is wrong because winds are
generally calmer at lower altitudes. As a result, Coriolis force is not as
effective as friction near the surface. 6-3 Convective circulation patterns associated with sea breezes are caused by A - warm, dense air moving inland from over the water. B - water absorbing and radiating heat faster than the land. C - cool, dense air moving inland from over the water. 6-3. Answer C. GFDPPM 6-11 (AW) During the day, land surfaces become warmer than the \w adjacent water surfaces. This warms the air above the land causing the air to rise. The rising air is replaced by the inland flow of cooler, denser air located over the water. As the warm air flows over the water it cools and descends. This starts the cycle all over again. During the night, the process is reversed as the land cools off faster than the water. Answer (A) is wrong because cool, not warm, air moves inland. Answer (B) is incorrect because sea breezes are a result of the land, not the water, absorbing and radiating heat faster.
6-4 How will frost on the wings of an airplane affect takeoff performance? A - Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability. B - Frost will change the camber of the wing, increasing its lifting capability. C - Frost will cause the airplane to become airborne with a higher angle of attack, decreasing the stall speed. 6-4. Answer A. GFDPPM 6-20 (PHS) Frost disrupts the smooth airflow over the wing and can cause early separation of the airflow, resulting in a loss of lift. Frost does not significantly change the camber (answer B), but it can disrupt the airflow and decrease the lift. The decreased lift caused by frost can cause the stall speed to increase, not decrease (answer C).
6-5 Every physical process of weather is accompanied by, or is the result of, a A - movement of air. B - pressure differential. C - heat exchange. 6-5. Answer C. GFDPPM 6-19 (AW) Every physical process of weather such as heating, cooling, evaporation, and condensation, is caused by, or is the result of, a heat exchange. Answers (A) and (B) are wrong because air movement and pressure differential are not always involved in the physical processes of weather. 6-6 A temperature inversion would most likely result in which weather condition? A - Clouds with extensive vertical development above an inversion aloft. B - Good visibility in the lower levels of the atmosphere and poor visibility above an inversion aloft. C - An increase in temperature as altitude is increased. 6-6. Answer C. GFDPPM 6-17 (AW) Normally, temperature decreases with altitude. During an inversion, cooler air is trapped beneath a warmer layer of air. Therefore, temperature increases with altitude. Answer (A) is wrong since inversions occur in stable air, and vertical development of clouds requires unstable air. Answer (B) is incorrect because weather and pollutants are trapped beneath inversions, and visibility near the surface is usually poor.
6-7 The most frequent type of ground or surface-based temperature inversion is that which is produced by A - terrestrial radiation on a clear, relatively still night. B - warm air being lifted rapidly aloft in the vicinity of mountainous terrain. C - the movement of colder air under warm air, or the movement of warm air over cold air. 6-7. Answer A. GFDPPM 6-18 (AW) An inversion commonly forms on clear, cool nights when the ground radiates heat and cools faster than the overlying air. Answers (B) and (C) are not examples of surface-based temperature inversions. Answer B) describes orographic lifting of air over rising terrain and answer (C) describes a cold front inversion.
6-8 Which weather conditions should be expected beneath a low-level temperature inversion layer when the relative humidity is high? A - Smooth air, poor visibility, fog, haze, or low clouds. B - Light wind shear, poor visibility, haze, and light ram. C - Turbulent air, poor visibility, fog, low stratus type clouds, and shower precipitation. 6-8. Answer A. GFDPPM 6-17 (AW) Low-level temperature inversions normally occur in stable, smooth air, with poor visibility due to trapped pollutants which are commonly referred to as condensation nuclei. In addition, high humidity tends to cause formation of fog and low clouds. Answers (B) and (C) are not entirely correct, because wind shear, turbulence, and showery precipitation are uncharacteristic conditions in the stable air below the inversion layer.
6-9 What is meant by the term "dewpoint"? A - The temperature at which condensation and evaporation are equal. B - The temperature at which dew will always form. C - The temperature to which air must be cooled to become saturated. 6-9. Answer C. GFDPPM 6-20 (AW) When air is cooled to its dewpoint, it can hold no more moisture, and is said to be saturated. Answer (A) is incorrect because dewpoint is not a measure of condensation or evaporation. Answer (8) is wrong because the formation of dew requires the surface temperature of Objects to cool below the dewpoint of the surrounding air.
6-10 The amount of water vapor which air can hold depends on the A - dewpoint. B - air temperature. C - stability of the air. 6-10. Answer B. GFDPPM 6-19 (AW) The amount of moisture in the air primarily depends on the temperature. For example, warm air can hold more moisture than cool air. The dewpoint (answer A) is the temperature at which the air reaches saturation (see explanation for Question 6-9). Answer (C) is wrong because stability of the air does not directly affect the moisture content.
6-11 Clouds, fog, or dew will always form when A - water vapor condenses. B - water vapor is present. C - relative humidity reaches 100 percent. 6-11. Answer A. GFDPPM 6-22 (AW) Condensation occurs when water vapor changes to liquid form. Examples are when water vapor changes to clouds, fog, or dew. Answer (B) is incorrect, because the water vapor, which is present in the air, must be cooled to a temperature at or near the dewpoint before it condenses to its liquid form. Relative humidity (answer C) is a measure of how much water the air can hold. At 100% relative humidity, the air is saturated, but the water vapor may not always condense to form clouds, fog, or dew.
6-12 What are the processes by which moisture is added to unsaturated air? A - Evaporation and sublimation. B - Heating and condensation. C - Supersaturation and evaporation. 6-12. Answer A. GFDPPM 6-19 (AW) Evaporation occurs when liquid water changes to water vapor. Sublimation is the changing of ice directly to water vapor. Both processes add moisture to the air. Answer (B) is wrong because condensation removes water vapor from the air by changing it to liquid form. Answer (C) is wrong because super-saturation can occur only in air that is already saturated after it has been cooled from a higher temperature to a temperature below the point at which saturation occurs.
6-13 Which conditions result in the formation of frost? A - The temperature of the collecting surface is at or below freezing when small droplets of moisture fall on the surface. B - The temperature of the collecting surface is at or below the dewpoint of the adjacent air and the dewpoint is below freezing. C - The temperature of the surrounding air is at or below freezing when small drops of moisture fall on the collecting surface. 6-13. Answer B. GFDPPM 6-20 (AW) When the dewpoint of the surrounding air is below freezing, and the collecting surface is at or below the dewpoint, water vapor sublimates directly into ice crystals or frost instead of condensing into dew. Answer (A) describes conditions resulting in frozen dew or raindrops, which form hard, clear ice, not frost. Answer (C) is incorrect because the collecting surface must be below the dewpoint, and the dewpoint must be below freezing.
6-14 The presence of ice pellets at the surface is evidence that there A - are thunderstorms in the area. B - has been cold frontal passage. C - is a temperature inversion with freezing rain at a higher altitude. 6-14. Answer C. GFDPPM 6-27 (AW) Due to a temperature inversion, a warm layer of air is aloft and keeps the rain in liquid form. As the rain falls through colder air, it begins to freeze, finally turning into ice pellets. Ice pellets always indicate freezing rain at a higher altitude. Ice pellets can form under various conditions, and do not necessarily indicate thunderstorms (answer A). Answer (B) is wrong because ice pellets may be formed in either a warm front or a cold front.
6-15 What measurement can be used to determine the stability of the atmosphere? A - Atmospheric pressure. B - Actual lapse rate. C - Surface temperature. 6-15. Answer B. GFDPPM 6-17 (AW) The stability of air refers to its resistance to displacement upward or downward; it is determined by the actual lapse rate. Lapse rate generally refers to the decrease in temperature with an increase in altitude. A high lapse rate tends to indicate unstable air, and a low lapse rate is an indicator of stability in the atmosphere. Answers (A) and (C) are wrong because air pressure and surface temperature do not directly affect stability.
,6-16 , What would decrease the stability of an air mass? A - Warming from below. B - Cooling from below. C - Decrease in water vapor. 6-16. Answer A. GFDPPM 6-16 (AW) Stability is altered by a change in the lapse rate of an air mass. Warming from below or cooling from above will increase the lapse rate and make the air less stable. Cooling from below (answer B) and a decrease in water vapor (answer C) both cause the air to become more dense and tend to increase stability.
6-17 What is a characteristic of stable air? A - Stratiform clouds. B - Unlimited visibility. C - Cumulus clouds. 6-17. Answer A. GFDPPM 6-23 (AW) There is very little vertical development of clouds in stable air, and stratiform clouds and poor visibility are typical. Cumulus clouds and good visibility are indicators of unstable air.
6-18 Moist, stable air flowing upslope can be expected to A - produce stratus type clouds. B - cause showers and thunderstorms. C - develop convective turbulence. 6-18. Answer A. GFDPPM 6-23 (AW) Stratus clouds are produced in stable air. When moist air flows upslope it cools to its saturation point, and clouds are formed. Showers and thunderstorms (answer B) and convective turbulence (answer C) are indicative of unstable air.
6-19 If an unstable air mass is forced upward, what type clouds can be expected? A - Stratus clouds with little vertical development. B - Stratus clouds with considerable associated turbulence. C - Clouds with considerable vertical development and associated turbulence. 6-19. Answer C. GFDPPM 6-25 (AW) Clouds with extensive vertical development are formed when unstable air is lifted. These cumulus type clouds are associated with moderate to severe turbulence. Stratus clouds (answers A and B) are a characteristic of smooth, stable air.
6-20 What feature is associated with a temperature inversion? A - A stable layer of air. B - An unstable layer of air. C - Chinook winds on mountain slopes. 6-20. Answer A. GFDPPM 6-17 (AW) Temperature inversions occur in stable air. Inversions cannot form in unstable air (answer B). As Chinook winds (answer C) descend, the temperature rises. This is the opposite of an inversion (cooler air under a warmer layer). In the U.S., the typical example of Chinook winds is the downslope, easterly flow from the Rocky Mountains.
6-21 What is the approximate base of the cumulus clouds if the surface air temperature at 1,000 feet MSL is 70°F and the dewpoint is 48°F? A - 4,000 feet MSL. B - 5,000 feet MSL. C - 6,000 feet MSL. 6-21. Answer C. GFDPPM 6-20 (AW) Cloud bases can be estimated by using a lapse rate of 4.5°F per 1,000 feet and the temperature/dewpoint spread (70 - 48 = 22). Divide 22 by 4.5 to find the approximate cloud base in thousands of feet. In this case, the cloud bases will be 4,889 (22 + 4.5 x 1,000) feet above the surface, or rounded to 5,000 feet. Since the surface is 1,000 feet MSL, the cloud base should be approximately 6,000 feet MSL.
6-22 At approximately what altitude above the surface would the pilot expect the base of cumuliform clouds if the surface air temperature is 82°F and the dewpoint is 38°F? A - 9,000 feet AGL. B - 10,000 feet AGL. C - 11,000 feet AGL. 6-22. Answer B. GFDPPM 6-20 (AW) See explanation for Question 6-21. The temperature/dewpoint spread is 44 (82 - 38). Divide 44 by the lapse rate of 4SF per 1,000 feet to find cloud bases at 9,778 feet AGL, rounded to 10,000 feet AGL.
6-23 What are characteristics of a moist, unstable air mass? A - Cumuliform clouds and showery precipitation. B - Poor visibility and smooth air. C - Stratiform clouds and showery precipitation. 6-23. Answer A. GFDPPM 6-29 (AW) Cumuliform clouds are indicative of unstable air. These clouds normally produce showery, not continuous, precipitation. Poor visibility, smooth air (answer B), and stratiform clouds (answer C) are characteristic of stable air.
6-24 What are characteristics of unstable air? A - Turbulence and good surface visibility. B - Turbulence and poor surface visibility. C - Nimbostratus clouds and good surface visibility. 6-24. Answer A. GFDPPM 6-29 (AW) The lifting motion of unstable air produces turbulence. Clouds and pollutants are not trapped as they are in stable layers of air, and good visibility is typical with unstable air. Poor surface visibility (answer B) and nimbostratus clouds (answer C) are typical of stable air masses.
6-25 A stable air mass is most likely to have which characteristic?
A - Showery precipitation. B - Turbulent air. C - Smooth air. 6-25. Answer C. GFDPPM 6-29 (AW) Stable air resists the lifting motion that is associated L". with turbulence, and is typically smooth. Showery precipitation (answer A) and turbulent air (answer B) are characteristics of unstable air.
6-26 The suffix "nimbus," used in naming clouds, means A - a cloud with extensive vertical development. B - a rain cloud. C - a middle cloud containing ice pellets. 6-26. Answer B. GFDPPM 6-22 (AW) The word "nimbus" is the Latin word for rainstorm or cloud, and is used today to designate rain clouds, such as cumulonimbus or nimbostratus. Answer (A) describes a cumuliform cloud which commonly is called a towering cumulus. Answer (C) is wrong because nimbus means a rain cloud, not a middle cloud, or a cloud with ice pellets.
6-27 Clouds are divided into four families according to their
A - outward shape. B - height range. C - composition. 6-27. Answer B. GFDPPM 6-22 (AW) Clouds are also grouped by families according to their altitudes (height range). The four families are low, middle, high, and clouds with extensive vertical development. Outward shape (answer A) and composition (answer C) are used to determine specific cloud types, such as cumulus, nimbostratus, and cirrus. These are not characteristics of the family classification.
6-28 The boundary between two different air masses is referred to as a A - frontolysis. B - frontogenesis. C - front. 6-28. Answer C. GFDPPM 6-30 (AW) The boundary area where two air masses of different properties meet is called a front. Frontolysis (answer A) is incorrect because it means the dissipation of a weather front. Frontogenesis (answer B) means the initial formation of a front.
6-29 One of the most easily recognized discontinuities across a front is A - a change in temperature. B - an increase in cloud coverage. C - an increase in relative humidity. 6-29. Answer A. GFDPPM 6-31 (AW) Since a front is the boundary between air masses of differing temperatures, one of the easiest ways to recognize frontal passage is the change in temperature. Cloud coverage (answer B) may increase or decrease, depending on the type of front. A change in relative humidity (answer C) also depends on the type of front.
6-30 One weather phenomenon which will always occur when flying across a front is a change in the A - wind direction. B - type of precipitation. C - stability of the air mass. 6-30. Answer A. GFDPPM 6-31 (AW) A shift in wind direction always occurs across a front. A change in the type of precipitation (answer B) sometimes, but not always, accompanies frontal passage. The same is true of stability (answer C); it does not always change.
6-31 Steady precipitation preceding a front is an indication of A - stratiform clouds with moderate turbulence. B - cumuli form clouds with little or no turbulence. C - stratiform clouds with little or no turbulence. 6-31. Answer C. GFDPPM 6-23,32 (AW) Steady precipitation, stratiform clouds, and little or no turbulence are all typical of stable air. Stratiform clouds and steady precipitation are not usually associated with moderate turbulence (answer A). Cumuliform clouds are found in unstable air and are accompanied by turbulence and showery precipitation (answer B).
6-32 What situation is most conducive to the formation of radiation fog? A - Warm, moist air over low, flatland areas on clear, calm nights. B - Moist, tropical air moving over cold, offshore water. C - The movement of cold air over much warmer water. 6-32. Answer A. GFDPPM 6-23 (AW) On clear, calm nights in flat areas, radiation fog forms when moist air cools to its dewpoint. Ground fog is a form of radiation fog. Fog that forms when warm, moist air moves over a cooler surface (answer B) is called advection fog. Cold, dry air moving over warmer water (answer C) causes the formation of steam fog.
6-33 If the temperature/dewpoint spread is small and decreasing, and the temperature is 62°F, what type weather is most likely to develop? A - Freezing precipitation. B - Thunderstorms. C - Fog or low clouds. 6-33. Answer C. GFDPPM 6-22 (AW) When the temperature/dewpoint spread decreases to zero, the likely result is the condensation of water vapor into visible moisture, such as fog or low clouds. Answer (A) is incorrect, since 62°F is well above freezing, and the water will be in liquid form, not freezing precipitation. Answer (B) is wrong because thunderstorms are associated with unstable air rather than temperature/dewpoint spread.
6-34 In which situation is advection fog most likely to form? A - A warm, moist air mass on the windward side of mountains. B - An air mass moving inland from the coast in winter. C - A light breeze blowing colder air out to sea. 6-34. Answer B. GFDPPM 6-23 (AW) t See explanation for Question 6-32. When warmer air L _ moves inland, advection fog is likely to form. Warm, moist air being lifted up a mountain slope (answer A) would form upslope fog. Colder air moving over the sea (answer C) would tend to form steam fog.
6-35 What types of fog depend upon wind in order to exist? A - Radiation fog and ice fog. B - Steam fog and ground fog. C - Advection fog and upslope fog. 6-35. Answer C. GFDPPM 6-23 (AW) See explanations for Questions 6-32 and 6-34. Answer (C) is the only correct choice since steam fog also requires the movement of air. Both ice fog and radiation fog (answer A), also known as ground fog (answer B), form in calm air.
6-36 Low-level turbulence can occur and icing can become hazardous in which type of fog? A - Rain-induced fog. B - Upslope fog. C - Steam fog. 6-36. Answer C. GFDPPM 6-23 (AW) Steam fog is formed by cold, dry air moving over warmer water. As the water particles evaporate and rise, they often freeze and fall back into the water. Icing and low-level turbulence can result. Normally, turbulence and icing are not common with rain-induced fog (answer A) or upslope fog (answer B).
6-37 An almond or lens-shaped cloud which appears stationary, but which may contain winds of 50 knots or more, is referred to as A - an inactive frontal cloud. B - a funnel cloud. C - a lenticular cloud. 6-37. Answer C. GFDPPM 6-50 (AW) Lenticular clouds are the lens-shaped clouds that form at the crests of mountain waves. An inactive frontal cloud (answer A) is obviously an incorrect choice. Frontal clouds with 50-knot winds would not be stationary. A funnel cloud (answer B) is associated with a tornado, and is neither lens-shaped or stationary.
6-38 Crests of standing mountain waves may be marked by stationary, lens-shaped clouds known as A - mammatocumulus clouds. B - standing lenticular clouds. C - roll clouds. 6-38. Answer B. GFDPPM 6-50 (AW) See explanation for Question 6-37. Mammatocumulus clouds (answer A) are typically associated with thunderstorms, not mountain waves. Roll clouds (answer C) are commonly found on the leading edge of thunderstorms, not mountain waves.
6-39 What clouds have the greatest turbulence? A - Towering cumulus. B - Cumulonimbus. C - Nimbostratus. 6-39. Answer B. GFDPPM 6-42 (AW) Cumulonimbus clouds, which form thunderstorms and ~ tornadoes, produce the most severe turbulence. Towering cumulus clouds (answer A) will have some turbulence, but not nearly as severe as a thunderstorm. Nimbostratus (answer C), a type of stratus cloud, usually has little or no turbulence.
6-40 What cloud types would indicate convective turbulence? A - Cirrus clouds. B - Nimbostratus clouds. C - Towering cumulus clouds. 6-40. Answer C. GFDPPM 6-45 (AW) Towering cumulus clouds are formed by convective currents, caused by rising heated air. These rising air currents cause convective turbulence. Cirrus clouds (answer A) are found at high altitude and are not formed by convection. Nimbostratus clouds (answer B) usually have little or no turbulence.
6-41 Possible mountain wave turbulence could be anticipated when winds of 40 knots or greater blow A - across a mountain ridge, and the air is stable. B - down a mountain valley, and the air is unstable. C - parallel to a mountain peak, and the air is stable. 6-41. Answer A. GFDPPM 6-50 (AW) Mountain waves are formed when strong winds (40 knots or greater) flow across a barrier, such as a mountain ridge. When the air is stable, the flow is laminar, or layered, and creates a series of waves. Unstable air that is forced upward tends to continue rising, often creating thunderstorms. Wind flowing down a valley (answer B) will not form mountain waves. Wind blowing parallel to a mountain peak (answer C) may create some turbulence, but a single peak would not normally cause a mountain wave.
6-42 Where does wind shear occur? A - Only at higher altitudes. B - Only at lower altitudes. C - At all altitudes, in all directions. 6-42. Answer C. GFDPPM 6-51 (AW) Wind shear can occur at middle and high altitudes near thunderstorms or the jet stream, and near the ground in the vicinity of thunderstorms or temperature inversions. The shear can be either vertical or horizontal. Answers (A) and (B) are wrong because wind shear can occur at any altitude.
6-43 When may hazardous wind shear be expected? A - When stable air crosses a mountain barrier where it tends to flow in layers forming lenticular clouds. B - In areas of low-level temperature inversion, frontal zones, and clear air turbulence. C - Following frontal passage when stratocumulus clouds form indicating mechanical mixing. 6-43. Answer B. GFDPPM 6-50, 51 (AW) Wind shear can be found above a temperature inversion when the surface air is cold and calm, and the warmer layer above it is moving at 25 knots or more. Since frontal zones are identified by a shift in the wind, wind shear can be expected. Clear air turbulence can be associated with either vertical or horizontal wind shear. Answer (A) describes a mountain wave, and wind shear mayor may not be present. Some turbulence is common with stratocumulus clouds (answer C), but hazardous wind shear is not typical.
6-44 A pilot can expect a wind shear zone in a temperature inversion whenever the windspeed at 2,000 to 4,000 feet above the surface is at least A- 10 knots. B -15 knots. C - 25 knots. 6-44. Answer C. GFDPPM 6-51 (AW) A temperature inversion with light surface winds may form near the surface on a clear night. You can expect a shear zone in the inversion if the winds at 2,000 to 4,000 feet are 25 knots or more. Answers (A) and (B) are incorrect because of insufficient wind speed 2,000 to 4,000 feet above the surface.
6-45 One in-flight condition necessary for structural icing to form is A - small temperature/dewpoint spread. B - stratiform clouds. C - visible moisture. 6-45. Answer C. GFDPPM 6-53 (AW) Structural icing requires two conditions to form: (1) visible moisture, such as rain or cloud droplets, and (2) temperature of the aircraft surface must be at or below freezing. A small temperature/dewpoint spread (answer A) may be present without visible moisture. Stratiform clouds (answer B) are not the only cloud types in which icing can occur.
6-46 In which environment is aircraft structural ice most likely to have the highest accumulation rate? A - Cumulus clouds with below freezing temperatures. B - Freezing drizzle. C - Freezing rain. 6-46. Answer C. GFDPPM 6-53 (AW) The rate of structural ice accumulation is usually the highest in freezing rain below a frontal surface. As the rain falls through air with temperatures below freezing it becomes supercooled. The supercooled drops freeze on impact with the large water droplets, and heavy rain accelerates the build up. Cumulus clouds (answer A) have varying sizes of water drops, and may not always cause a rapid buildup of ice. Freezing drizzle (answer B) has smaller droplets and icing will build up more slowly than larger drops.
6-47 Why is frost considered hazardous to flight? A - Frost changes the basic aerodynamic shape of the airfoils, thereby decreasing lift. B - Frost slows the airflow over the airfoils, thereby increasing control effectiveness. C - Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capability. 6-47. Answer C. GFDPPM 6-20 (AW) See explanation for Question 6-4. Frost does not significantly change the shape of the airfoil (answer A), but will cause early separation of the airflow. The airflow over the airfoil is not slowed (answer B), and control effectiveness is not increased.
6-48 How does frost affect the lifting surfaces of an airplane on takeoff? A - Frost may prevent the airplane from becoming airborne at normal takeoff speed. B - Frost will change the camber of the wing, increasing lift during takeoff. C - Frost may cause the airplane to become airborne with a lower angle of attack at a lower indicated airspeed. 6-48. Answer A. GFDPPM 6-20 (AW) See explanations for Questions 6-4 and 6-47. By disrupting the airflow over the wings, frost can prevent an airplane from becoming airborne at the normal takeoff speed. Frost does not change the camber of a wing (answer B). The disrupted airflow would prevent the airplane from becoming airborne at a lower airspeed (answer C). Ground effect, not frost, is what causes an airplane to become airborne at a lower-than-normal angle of attack and airspeed.
6-49 The conditions necessary for the formation of cumulonimbus clouds are a lifting action and A - unstable air containing an excess of condensation nuclei. B - unstable, moist air. C - either stable or unstable air. 6-49. Answer B. GFDPPM 6-38, 42 (AW) Three conditions are normally required for the formation of cumulonimbus clouds. These are lifting action, instability, and moisture. An excess of condensation nuclei (answer A) would aid in the formation of water droplets, L but moisture must also be present. Stable air (answer C) resists any upward (or downward) displacement and, therefore, inhibits the formation of cumulonimbus clouds.
6-50 What feature is normally associated with the cumulus stage of a thunderstorm?
A - Roll cloud. B - Continuous updraft. C - Frequent lightning. 6-50. Answer B. GFDPPM 6-40 (AW) In the early, or cumulus, stage of a thunderstorm, continuous updrafts cause the cloud to build upwards. A roll cloud (answer A) forms at the leading edge of a mature thunderstorm. Frequent lightning (answer C) is seldom found in the cumulus stage, but is typical of the mature stage.
6-51 Which weather phenomenon signals the beginning of the mature stage of a thunderstorm? A - The appearance of an anvil top. B - Precipitation beginning to fall. C - Maximum growth rate of the clouds. 6-51. Answer B. GFDPPM 6-41 (AW) The mature stage of a thunderstorm begins when the rain drops grow too large to be supported by the updrafts, and precipitation begins to fall. An anvil top (answer A) appears as a thunderstorm reaches the dissipating stage, not the mature stage. Maximum growth rate of the clouds (answer C) occurs during the cumulus stage, not the mature stage.
6-52 What conditions are necessary for the formation of thunderstorms? A - High humidity, lifting force, and unstable conditions. B - High humidity, high temperature, and cumulus clouds. C - Lifting force, moist air, and extensive cloud cover. 6-52. Answer A. GFDPPM 6-38 (AW) See explanation for Question 6-49. As moist, unstable air is lifted, it builds cumulonimbus clouds, which form thunderstorms. Unless unstable conditions are present, thunderstorms will not form, so answers (B) and (C) are incorrect.
6-53 During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts? A- Cumulus. B - Dissipating. C- Mature. 6-53. Answer B. GFDPPM 6-41 (AW) As a thunderstorm dissipates, updrafts weaken and downdrafts become predominate. Also see explanations for Questions 6-50 and 6-51.
6-54 Thunderstorms reach their greatest intensity during the A - mature stage. B - downdraft stage. C - cumulus stage. 6-54. Answer A. GFDPPM 6-41 (AW) Thunderstorms are most violent during the mature stage, with strong updrafts and downdrafts, severe turbulence, lightning, heavy rain, hail, strong surface winds, and gust fronts. Neither the dissipating stage, with its downdrafts (answer B), or the cumulus stage (answer C) and its updrafts, are as intense as the mature stage.
6-55 Thunderstorms which generally produce the most intense hazard to aircraft are
A - squall line thunderstorms. B - steady-state thunderstorms. C - warm front thunderstorms. 6-55. Answer A. GFDPPM 6-39 (AW) Squall lines often contain severe steady-state thunderstorms and present the most hazardous conditions to aircraft. Steady-state thunderstorms (answer B) by themselves are hazardous, but squall line thunderstorms are the most severe. Warm front thunderstorms (answer C) are generally not as severe as squall line thunderstorms.
6-56 A nonfrontal, narrow band of active thunderstorms that often develop ahead of a cold front is known as a A - prefrontal system. B - squall line. C - dryline. 6-56. Answer B. GFDPPM 6-39 (AW) Squall lines are a narrow band of thunderstorms that often develop ahead of a cold front. A prefrontal system (answer A) or dry line (answer C) are not terms used to describe this narrow band of thunderstorms.
6-57 If there is thunderstorm activity in the vicinity of an airport at which you plan to land, which hazardous atmospheric phenomenon might be expected on the landing approach? A - Precipitation static. B - Wind-shear turbulence. C - Steady rain. 6-57. Answer B. GFDPPM 6-50 (AW) In the vicinity of thunderstorms, hazardous wind-shear turbulence should always be expected. Precipitation static (answer A), known as "St. Elmo's fire;' is not hazardous. Steady rain (answer C) is not normally found with thunderstorms, and is not hazardous unless it is freezing.
6-58 Upon encountering severe turbulence, which flight condition should the pilot attempt to maintain? A - Constant altitude and airspeed. B - Constant angle of attack. C - Level flight attitude. 6-58. Answer C. GFDPPM 6-44 (AW) If entering severe turbulence, the best procedure is to .~ slow to a speed not faster than maneuvering airspeed and maintain a constant level flight attitude. Variations in airspeed and altitude should be expected and tolerated. Constant altitude and airspeed (answer A) or constant angle of attack (answer B) will be practically impossible to maintain.
6-59 Which weather phenomenon is always associated with a thunderstorm? A - Lightning. B - Heavy rain. C - Hail. 6-59. Answer A. GFDPPM 6-43 (AW) Since thunder is caused by lightning, the name thunderstorm implies that lightning is always associated with a thunderstorms. Heavy rain (answer B) or hail (answer C) may not always be present, depending on the severity of the storm.
6-60 Wingtip vortices are created only when an aircraft is A - operating at high airspeeds. B - heavily loaded. C - developing lift. 6-60. Answer C. GFDPPM 6-47 (PHS) Anytime an aircraft is developing lift, air flows over the wingtip to form wingtip vortices. High speed (answer A) would tend to decrease wingtip vortices, and the heavier an aircraft (answer B), the stronger the vortices, but they are created at any weight.
6-61 The greatest vortex strength occurs when the generating aircraft is A - light, dirty, and fast. B - heavy, dirty, and fast. C - heavy, clean, and slow. 6-61. Answer C. GFDPPM 6-47 (PHS) Heavy aircraft, in a clean configuration, flying at low airspeeds with high angles of attack, generate the strongest vortices. A "dirty" configuration, or gear and flaps down (answers A and B), reduces the vortex strength.
6-62 Wingtip vortices created by large aircraft tend to A - sink below the aircraft generating turbulence. B - rise into the traffic pattern. C - rise into the takeoff or landing path of a crossing runway. 6-62. Answer A. GFDPPM 6-47 (PHS) Wingtip vortices tend to sink below the flight path of the aircraft which generated them. Vortices are not known to rise (answers B and C).
6-63 When taking off or landing at an airport where heavy aircraft are operating, one should be particularly alert to the hazards of wingtip vortices because this turbulence tends to A - rise from a crossing runway into the takeoff or landing path. B - rise into the traffic pattern area surrounding the airport. C - sink into the flightpath of aircraft operating below the aircraft generating the turbulence. 6-63. Answer C. GFDPPM 6-47 (PHS) See explanation for Question 6-62.
6-64 The wind condition that requires maximum caution when avoiding wake turbulence on landing is a A - light, quartering headwind. B - light, quartering tailwind. C - strong headwind. 6-64. Answer B. GFDPPM 6-47 (PHB) A light, quartering tailwind is the most hazardous because it can move the upwind vortex over the runway and forward into the landing zone. A light, quartering headwind (answer A) would move the upwind vortex over the runway, but would also move it back away from the landing zone. A strong headwind (answer C) would help dissipate wake turbulence, and is not as hazardous as a light, quartering tailwind.
6-65 When landing behind a large aircraft, the pilot should avoid wake turbulence by staying A - above the large aircraft's final approach path and landing beyond the large aircraft's touchdown point. B - below the large aircraft's final approach path and landing before the large aircraft's touchdown point. C - above the large aircraft's final approach path and landing before the large aircraft's touchdown point. 6-65. Answer A. GFDPPM 6-47 (PH B) Since wake turbulence tends to sink, a following aircraft should stay above the large aircraft's flight path and land beyond its touchdown point. Staying below the large aircraft's final approach path (answer B) or landing before its touchdown point (answers B and C) would place the aircraft in the path of the wake turbulence.
6-66 When departing behind a heavy aircraft, the pilot , should avoid wake turbulence by maneuvering the aircraft A - below and downwind from the heavy aircraft. B - above and upwind from the heavy aircraft. C - below and upwind from the heavy aircraft. 6-66. Answer B. GFDPPM 6-47 (PH B) Because wake turbulence tends to sink and drift downwind, an aircraft should stay above and upwind of the preceding aircraft. Maneuvering below and downwind (answer A) would put the aircraft into the wake turbulence. Depending on the circumstances, below and upwind (answer C) may not keep the aircraft clear.
6-67 When landing behind a large aircraft, which procedure should be followed for vortex avoidance? A - Stay above its final approach flightpath all the way to touchdown. B - Stay below and to one side of its final approach flightpath. C - Stay well below its final approach flightpath and land at least 2,000 feet behind. 6-67. Answer A. GFDPPM 6-47 Vortices (wake turbulence) are generated at an aircraft's wingtips and develop when an aircraft is producing lift. Wingtip vortices tend to sink below the flight path of the generating aircraft. Therefore, remaining above the glide path and landing beyond the touchdown point of a large aircraft is a good way to avoid wake turbulence.
6-68 How does the wake turbulence vortex circulate around each wingtip? A - Inward, upward, and around each tip. B - Inward, upward, and counterclockwise. C - Outward, upward, and around each tip. 6-68. Answer C. GFDPPM 6-47 (PHB) Wake turbulence vortices are a by-product of lift. They move outward, upward and around each wingtip. |
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