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Most bird strikes on aerodromes involve a small range of species: primarily gulls (especially black-headed and common gulls), waders (mostly lap wing, but also golden plover and oystercatcher), pigeons, corvids, starling, skylark, swift, swallow and martins. There is a clear relation between bird mass and risk that the aircraft will be damaged: small birds (less than 100g) cause damage on less than 3% of occasions when they are struck; medium-sized birds (101g-1000g) -12%; and large birds (over 1000g) - nearly 23%. There is also a strong relation between bird numbers and the chances that the aircraft will be damaged: single birds cause damage on 8% of occasions; small flocks (2-10) - 14%; and larger flocks (11-100 birds) - 40%. Thus, species which are larger than 100g or occur on aerodromes in flocks are most likely to cause damage to aircraft. Gulls, waders, pigeons, corvids and starling all occur commonly on aerodromes, are responsible for the majority of bird strikes and are most likely to cause damage. However, they also respond well to habitat management and active dispersal techniques and are, therefore, controllable. These birds can be classed as the Priority Group for control. Many other species, most of which are less susceptible to available control measures, are involved in aerodrome bird strikes. Total numbers of bird strikes are not very useful in assessing an aerodrome＇s bird hazard or performance in controlling it. However, a more detailed breakdown can provide useful insights, as follows: ? Priority group species. If a high proportion of an aerodrome＇s bird strikes involve priority group species, then the hazard level is probably high and control standard low. ? Multiple strikes. If there are multiple strikes with priority group species, it is an indication that flocks are permitted to build up and remain on or close to runways. Bird strikes, especially multiple strikes, with these species commonly cause damage and, even if the reporting standard is low, these incidents cannot be suppressed. Thus, the hazard is obviously high and there are problems with controlling it. ? Small birds. All aerodromes have many small birds which are inevitably involved in strikes: Skylarks all year but especially in autumn; finches in winter; and swifts, swallows and martins in summer. If the common small birds are absent from an aerodrome＇s strike statistics, it can be assumed that the true situation is not reflected: the reporting standard must be suspect. ? Less common medium-sized and large species. The significance of the occurrence of these species in an aerodrome＇s strike records can only be properly interpreted with a detailed knowledge of local conditions. By adopting priorities of minimizing strikes with: (1) the greatest potential for serious accidents (multiple strikes with large birds); (2) priority group species; and (3) controllable species, and by using the prevalence of strikes with small birds as a check of reporting standard, the data can provide indicators of hazard level and performance which are independent of comparison with other aerodromes.2. What can we learn from Para. 1?
Most bird strikes on aerodromes involve a small range of species: primarily gulls (especially black-headed and common gulls), waders (mostly lap wing, but also golden plover and oystercatcher), pigeons, corvids, starling, skylark, swift, swallow and martins. There is a clear relation between bird mass and risk that the aircraft will be damaged: small birds (less than 100g) cause damage on less than 3% of occasions when they are struck; medium-sized birds (101g-1000g) -12%; and large birds (over 1000g) - nearly 23%. There is also a strong relation between bird numbers and the chances that the aircraft will be damaged: single birds cause damage on 8% of occasions; small flocks (2-10) - 14%; and larger flocks (11-100 birds) - 40%. Thus, species which are larger than 100g or occur on aerodromes in flocks are most likely to cause damage to aircraft. Gulls, waders, pigeons, corvids and starling all occur commonly on aerodromes, are responsible for the majority of bird strikes and are most likely to cause damage. However, they also respond well to habitat management and active dispersal techniques and are, therefore, controllable. These birds can be classed as the Priority Group for control. Many other species, most of which are less susceptible to available control measures, are involved in aerodrome bird strikes. Total numbers of bird strikes are not very useful in assessing an aerodrome＇s bird hazard or performance in controlling it. However, a more detailed breakdown can provide useful insights, as follows: ? Priority group species. If a high proportion of an aerodrome＇s bird strikes involve priority group species, then the hazard level is probably high and control standard low. ? Multiple strikes. If there are multiple strikes with priority group species, it is an indication that flocks are permitted to build up and remain on or close to runways. Bird strikes, especially multiple strikes, with these species commonly cause damage and, even if the reporting standard is low, these incidents cannot be suppressed. Thus, the hazard is obviously high and there are problems with controlling it. ? Small birds. All aerodromes have many small birds which are inevitably involved in strikes: Skylarks all year but especially in autumn; finches in winter; and swifts, swallows and martins in summer. If the common small birds are absent from an aerodrome＇s strike statistics, it can be assumed that the true situation is not reflected: the reporting standard must be suspect. ? Less common medium-sized and large species. The significance of the occurrence of these species in an aerodrome＇s strike records can only be properly interpreted with a detailed knowledge of local conditions. By adopting priorities of minimizing strikes with: (1) the greatest potential for serious accidents (multiple strikes with large birds); (2) priority group species; and (3) controllable species, and by using the prevalence of strikes with small birds as a check of reporting standard, the data can provide indicators of hazard level and performance which are independent of comparison with other aerodromes.1. Medium-sized birds (101g-1000g) cause damage on less than of occasions when they are struck
Normally, air must become saturated for condensation or sublimation to occur. Saturation may result from cooling temperature, increasing dew point, or both. Cooling is far more predominant. In aviation community the clouds are classified as 14 sorts. They are cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus, fractonimbus, altocumulus, altostratus, cirrus, cirrocumulus and cirrostratus. Clouds are the weather signposts in the sky to the pilots. They give them an indication of air motion, stability, and moisture. Clouds help to visualize weather conditions and potential weather hazards pilots might encounter in flight. Let’s examine these signposts and how to identify them. For identification purposes, you need be concerned only with the more basic cloud types, which are divided into four families. The families are: high clouds, middle clouds, low clouds. The first three families are further classified according to the way they are formed. Clouds formed by vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance. In addition to the above, the prefix nimbo or the suffix nimbus means raincloud. Thus, stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is cumulonimbus. Clouds broken into fragments are often identified by adding the prefix fractus; for example, fragmentary cumulus is fractocumulus. The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from above 20,000 feet in middle latitudes. In the middle cloud family are altostratus and altocumulus. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6,500 to 20,000 feet in middle latitudes. In the low cloud family are the cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus，fractonimbus. Low clouds are almost entirely water, but at times the water may be supercooled. Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6,500 feet in middle latitudes. The vertically developed cloud includes cumulus congestus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases range from 1,000 feet or less to above 10,000 feet.5. Vertically developed clouds usually contain （ ）.
Normally, air must become saturated for condensation or sublimation to occur. Saturation may result from cooling temperature, increasing dew point, or both. Cooling is far more predominant. In aviation community the clouds are classified as 14 sorts. They are cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus, fractonimbus, altocumulus, altostratus, cirrus, cirrocumulus and cirrostratus. Clouds are the weather signposts in the sky to the pilots. They give them an indication of air motion, stability, and moisture. Clouds help to visualize weather conditions and potential weather hazards pilots might encounter in flight. Let’s examine these signposts and how to identify them. For identification purposes, you need be concerned only with the more basic cloud types, which are divided into four families. The families are: high clouds, middle clouds, low clouds. The first three families are further classified according to the way they are formed. Clouds formed by vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance. In addition to the above, the prefix nimbo or the suffix nimbus means raincloud. Thus, stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is cumulonimbus. Clouds broken into fragments are often identified by adding the prefix fractus; for example, fragmentary cumulus is fractocumulus. The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from above 20,000 feet in middle latitudes. In the middle cloud family are altostratus and altocumulus. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6,500 to 20,000 feet in middle latitudes. In the low cloud family are the cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus，fractonimbus. Low clouds are almost entirely water, but at times the water may be supercooled. Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6,500 feet in middle latitudes. The vertically developed cloud includes cumulus congestus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases range from 1,000 feet or less to above 10,000 feet.4. What state is the water present in low clouds? （ ）
Normally, air must become saturated for condensation or sublimation to occur. Saturation may result from cooling temperature, increasing dew point, or both. Cooling is far more predominant. In aviation community the clouds are classified as 14 sorts. They are cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus, fractonimbus, altocumulus, altostratus, cirrus, cirrocumulus and cirrostratus. Clouds are the weather signposts in the sky to the pilots. They give them an indication of air motion, stability, and moisture. Clouds help to visualize weather conditions and potential weather hazards pilots might encounter in flight. Let’s examine these signposts and how to identify them. For identification purposes, you need be concerned only with the more basic cloud types, which are divided into four families. The families are: high clouds, middle clouds, low clouds. The first three families are further classified according to the way they are formed. Clouds formed by vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance. In addition to the above, the prefix nimbo or the suffix nimbus means raincloud. Thus, stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is cumulonimbus. Clouds broken into fragments are often identified by adding the prefix fractus; for example, fragmentary cumulus is fractocumulus. The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from above 20,000 feet in middle latitudes. In the middle cloud family are altostratus and altocumulus. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6,500 to 20,000 feet in middle latitudes. In the low cloud family are the cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus，fractonimbus. Low clouds are almost entirely water, but at times the water may be supercooled. Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6,500 feet in middle latitudes. The vertically developed cloud includes cumulus congestus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases range from 1,000 feet or less to above 10,000 feet.3. The high cloud family includes （ ）.
Normally, air must become saturated for condensation or sublimation to occur. Saturation may result from cooling temperature, increasing dew point, or both. Cooling is far more predominant. In aviation community the clouds are classified as 14 sorts. They are cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus, fractonimbus, altocumulus, altostratus, cirrus, cirrocumulus and cirrostratus. Clouds are the weather signposts in the sky to the pilots. They give them an indication of air motion, stability, and moisture. Clouds help to visualize weather conditions and potential weather hazards pilots might encounter in flight. Let’s examine these signposts and how to identify them. For identification purposes, you need be concerned only with the more basic cloud types, which are divided into four families. The families are: high clouds, middle clouds, low clouds. The first three families are further classified according to the way they are formed. Clouds formed by vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance. In addition to the above, the prefix nimbo or the suffix nimbus means raincloud. Thus, stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is cumulonimbus. Clouds broken into fragments are often identified by adding the prefix fractus; for example, fragmentary cumulus is fractocumulus. The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from above 20,000 feet in middle latitudes. In the middle cloud family are altostratus and altocumulus. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6,500 to 20,000 feet in middle latitudes. In the low cloud family are the cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus，fractonimbus. Low clouds are almost entirely water, but at times the water may be supercooled. Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6,500 feet in middle latitudes. The vertically developed cloud includes cumulus congestus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases range from 1,000 feet or less to above 10,000 feet.2. What does nimbo mean?
Normally, air must become saturated for condensation or sublimation to occur. Saturation may result from cooling temperature, increasing dew point, or both. Cooling is far more predominant. In aviation community the clouds are classified as 14 sorts. They are cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus, fractonimbus, altocumulus, altostratus, cirrus, cirrocumulus and cirrostratus. Clouds are the weather signposts in the sky to the pilots. They give them an indication of air motion, stability, and moisture. Clouds help to visualize weather conditions and potential weather hazards pilots might encounter in flight. Let’s examine these signposts and how to identify them. For identification purposes, you need be concerned only with the more basic cloud types, which are divided into four families. The families are: high clouds, middle clouds, low clouds. The first three families are further classified according to the way they are formed. Clouds formed by vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance. In addition to the above, the prefix nimbo or the suffix nimbus means raincloud. Thus, stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is cumulonimbus. Clouds broken into fragments are often identified by adding the prefix fractus; for example, fragmentary cumulus is fractocumulus. The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from above 20,000 feet in middle latitudes. In the middle cloud family are altostratus and altocumulus. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6,500 to 20,000 feet in middle latitudes. In the low cloud family are the cumulus, cumulus congestus, cumulonimbus, fractocumulus, stratus, stratocumulus, nimbostratus, fractostratus，fractonimbus. Low clouds are almost entirely water, but at times the water may be supercooled. Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6,500 feet in middle latitudes. The vertically developed cloud includes cumulus congestus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases range from 1,000 feet or less to above 10,000 feet.1. How many sorts are the clouds classified into in the aviation community?
In the U.S., airline schedules are challenging even on good weather days. When bad weather limits the capacities of airports and airspace, U.S. Federal Aviation Administration (FAA) Traffic Flow Management (TFM) specialists at the Air Traffic Control System Command Center (ATCSCC) may institute various TFM initiatives to manage excess demand. These actions are undertaken as part of a collaborative decision-making (CDM) process involving the FAA and major airlines. FAA TFM actions can be divided into strategic actions, which are typically taken at least 2 hours before weather is expected to affect operations and tactical actions, which are taken within 2 hours of weather. Strategic TFM actions include ground delay programs (GDPs), which reduce the demand to a given airport by spreading out the original schedule over time, and playbook actions, which reroute large blocks of traffic around regions of en-route airspace according to predefined plans. Tactical TFM actions include ground stops (GSs), which stop flight on the ground that are due to arrive later at given airport, coded departure routes (CDRs), which reroutes specific flights from a given airport, and reroutes around the weather. In addition, airlines may respond to weather or forecast weather with flight cancellations and, if necessary, diversions. Strategic TFM decision making may take place in the context of significant uncertainty with respect to both demand and weather information. With the advent of CDM, there has been an overall improvement in the extent and quality of information exchanged regarding departure times and cancellations.5. In the context of significant uncertainty with respect to both demand and weather information, （ ） may take place.
In the U.S., airline schedules are challenging even on good weather days. When bad weather limits the capacities of airports and airspace, U.S. Federal Aviation Administration (FAA) Traffic Flow Management (TFM) specialists at the Air Traffic Control System Command Center (ATCSCC) may institute various TFM initiatives to manage excess demand. These actions are undertaken as part of a collaborative decision-making (CDM) process involving the FAA and major airlines. FAA TFM actions can be divided into strategic actions, which are typically taken at least 2 hours before weather is expected to affect operations and tactical actions, which are taken within 2 hours of weather. Strategic TFM actions include ground delay programs (GDPs), which reduce the demand to a given airport by spreading out the original schedule over time, and playbook actions, which reroute large blocks of traffic around regions of en-route airspace according to predefined plans. Tactical TFM actions include ground stops (GSs), which stop flight on the ground that are due to arrive later at given airport, coded departure routes (CDRs), which reroutes specific flights from a given airport, and reroutes around the weather. In addition, airlines may respond to weather or forecast weather with flight cancellations and, if necessary, diversions. Strategic TFM decision making may take place in the context of significant uncertainty with respect to both demand and weather information. With the advent of CDM, there has been an overall improvement in the extent and quality of information exchanged regarding departure times and cancellations.4. Airlines may not respond to weather or forecast weather with （ ）.
In the U.S., airline schedules are challenging even on good weather days. When bad weather limits the capacities of airports and airspace, U.S. Federal Aviation Administration (FAA) Traffic Flow Management (TFM) specialists at the Air Traffic Control System Command Center (ATCSCC) may institute various TFM initiatives to manage excess demand. These actions are undertaken as part of a collaborative decision-making (CDM) process involving the FAA and major airlines. FAA TFM actions can be divided into strategic actions, which are typically taken at least 2 hours before weather is expected to affect operations and tactical actions, which are taken within 2 hours of weather. Strategic TFM actions include ground delay programs (GDPs), which reduce the demand to a given airport by spreading out the original schedule over time, and playbook actions, which reroute large blocks of traffic around regions of en-route airspace according to predefined plans. Tactical TFM actions include ground stops (GSs), which stop flight on the ground that are due to arrive later at given airport, coded departure routes (CDRs), which reroutes specific flights from a given airport, and reroutes around the weather. In addition, airlines may respond to weather or forecast weather with flight cancellations and, if necessary, diversions. Strategic TFM decision making may take place in the context of significant uncertainty with respect to both demand and weather information. With the advent of CDM, there has been an overall improvement in the extent and quality of information exchanged regarding departure times and cancellations.3. Rerouting large blocks of traffic around regions of en-route airspace according to predefined plans is （ ）.
