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Question 221-1 : Which of the following statements is correct about the 'gain' knob of an awr ? [ Certification weather ]
It adjusts the receiver sensitivity in order to achieve optimum target acquisition.
Weather radar operationthe flight crew uses four features to operate the radar antenna tilt this is the angle between the centre of the beam and the horizon.range control of the nd this has an essential influence on the optimum tilt setting.gain control this adjusts the sensitivity of the receiver.radar modes weather wx or weather + turbulence wx + t.source safetyfirst.airbus.com/the 'gain' of a radar adjusts the sensitivity of the receiver. a high gain high sensitivity means that even very small reflected pulses will show up as returns on the radar screen, but this means that the radar screen can easily get too cluttered with very small returns that we do not want to see.a low gain will make the radar less sensitive, and so only large returns will actually show up on the display. changing the gain also changes the sensitivity of the different colour bands, which is very useful.the gain can be changed in flight, for instance when looking at a cumulus cloud that does not look too violent, we might be happy to proceed through it if we know which bits are worst within it. with standard gain, the whole cloud might be green, but with the gain set a little higher, it may be possible to see the worst patches within it. the same goes for a thunderstorm that is huge and all red on the display, reducing the gain can give more detail about the weather within.
Question 221-2 : One of the advantages of the secondary surveillance radar ssr systems over the primary surveillance radar psr systems is that ssr can provide more information. how does this happen ?
Atc ssr systems can interrogate aircraft transponders and elicit replies.
One of the biggest differences between a primary surveillance radar psr and a secondary surveillance radar ssr is that the psr relies on the reception of a reflected pulse the echo of the transmitted pulse. on the other hand, secondary radar ssr , receives pulses transmitted by the target in response to interrogation pulses has the ability to interrogate an aircraft using a transponder and elicit replies.
Question 221-3 : Complete the following statement. on a multicolor awr, magenta indicates a higher than red. ?
Rainfall intensity.
Refer to figure...airborne weather radar..airborne weather radar is designed for avoiding severe weather, not for penetrating it. it detects drops of precipitation such as rain/snow/hail => rainfall intensity. therefore, do not try to use it to avoid instrument weather associated with clouds and fog – it does not provide any assurance of avoiding ifr weather conditions...reflectivity..weather detection is based on the reflectivity of water droplets. the weather echo appears on the navigation display nd with a color scale. a typical three color system will be green, yellow and red, with red being the most severe. a typical four color system will be green, yellow, red and magenta, with magenta being the most severe.
Question 221-4 : During the flight, you observe that what you saw as one return on your awr screen, has now turned into two separate echoes. which of the following statements is correct ?
This is normal since with decreasing range the beam width azimuth will also decrease.
Refer to figure...airborne weather radar..for efficient target resolution, the beamwidth must be as narrow as possible, and with decreasing range the beam width azimuth will also decrease. as a result, two distant clouds might appear as one large return until, at a closer range, they are displayed correctly as separate entities.
Question 221-5 : Regarding the awr, what is the shadowing effect ?
A cloud behind another cloud which cannot be detected.
Refer to figure...weather attenuation..the weather radar display depends on signal returns the more intense the precipitation, the less distance the radar can see through. therefore when the radar echo is unable to make the two way trip through heavy precipitation, a shadowing effect occurs...the stronger the rainstorm, the more radar energy will be scattered by weather attenuation. in simple words, radar attenuation is simply the absorption or reflection of radar signals as the radar pulse penetrates an area of precipitation, preventing that radar from detecting any additional cells that lie behind the first storm...tip for avoiding shadows to accurately interpret your radar returns, aim the tilt on your radar down far enough to paint the ground, then look for returns.... . if you see a potential shadow a dark, blank area , look for a cell in front of the shadow. if you see a storm before the shadow, avoid it.. . . if you don't see any storm cells in front of the dark area, it's probably not a shadow, but may be a large lake or a tall mountain equally disturbing, depending on your altitude.
Question 221-6 : How should one avoid a thunderstorm ?
Fly on the upwind side of the storm, avoiding red and magenta coloured areas on the screen.
Thunderstorm avoidanceit’s simple airplanes and thunderstorms don’t mix. flying through a thunderstorm, especially in a light aircraft, can be deadly. thunderstorms can produce airframe shattering turbulence, damaging hail, sudden and dramatic wind shear, strong, gusty winds—sometimes as much as 20 miles from the edge of a cell. never regard any thunderstorm lightly.according to icao ac 120 88a appendix 1 . avoid any convective activity cbs en route by at least 20 nautical miles.hail and severe turbulence can exist well outside of the storm cloud. if you plan to deviate around a thunderstorm => fly on the upwind side so that your path does not converge with the path of the storm. generally speaking, you'll find the best chance for clear, smooth air on the upwind side of a thunderstorm. do not be tempted to try to fly under a thunderstorm, even if you can see through the rain on the other side => besides rain, hail and lighting, the area under a thunderstorm typically contains severe turbulence including microbursts, windshear and downdrafts trying to fly over a developing storm is also dangerous => the rising clouds can usually outclimb your aircraft.if your aircraft is equipped with a weather avoidance system, such as a weather radar, you can use it to avoid thunderstorms. you should avoid intense thunderstorms echoes by at least 20 nm.airborne weather radar is designed for avoiding severe weather, not for penetrating it. it detects drops of precipitation. therefore, do not try to use it to avoid instrument weather associated with clouds and fog – it does not provide any assurance of avoiding ifr weather conditions.
Question 221-7 : Mode s transponders receive interrogations from ?
Ssr ground station and tcas.
Los 062.03.04.02.09 explain that mode s transponders receive interrogations from tcas and ssr ground stations.mode s is a large improvement compared to modes a and c. mode s has several further communication capabilities compared to modes a and c. transponders in mode a can only provide response including the aircraft identification 4 digit transponder / squawk code. transponders in mode c, in addition to the identification, can also provide an altitude information in the response. transponders in mode s can provide all of this information and multitude of additional data, such as • callsign. • specific aircraft identification / registration address. • altitude information in 25 ft increments as opposed to 100 ft increments for mode c. • datalink information, allowing exchange of atc and flight operations related info between the atc and the aircraft.mode s can transmit to ssr stations as well as other aircraft. mode s transponders in air to air communication mode may work as traffic avoidance systems however messaging may also become available.
Question 221-8 : State which information can be presented on the atc display system.1. pressure altitude..2. flight level..3. flight number or aircraft registration number..4. ground speed..5. tas. ?
1, 2, 3, and 4.
Question 221-9 : No radar returns are received from an area which is located behind an area where intense precipitation is being displayed by the airborne weather radar. what is the most appropriate conclusion ?
The weather conditions are unknown.
Refer to figure...weather attenuation..the weather radar display depends on signal returns the more intense the precipitation, the less distance the radar can see through. therefore when the radar echo is unable to make the two way trip through heavy precipitation, a shadowing effect occurs...the stronger the rainstorm, the more radar energy will be scattered by weather attenuation. in simple words, radar attenuation or shadowing is simply the absorption or reflection of radar signals as the radar pulse penetrates an area of precipitation, preventing that radar from detecting any additional cells that lie behind the first storm.... the awr is blind to whatever conditions may be lurking behind the thunderstorm. in the area where the shadowing occurs, conditions are unknown.
Question 221-10 : Complete the following sentence. the secondary surveillance radar ssr mode s is compatible with 1 but also provides the information to 2 . ?
1 ssr modes a and c 2 automatic dependent surveillance broadcast ads b.
Secondary surveillance radar ssr modes and codes... mode a. interrogator requests position information from the transponder. provides solely 2d position information that is presented on the screen of the controller in the horizontal plane.. mode c. interrogator requests position and pressure altitude information from the transponder. provides 3d position information that is presented on the screen of the controller in the horizontal plane with an altitude indication.. mode s. in addition to the functions of mode c, it sends a request for data transmission as well. mode s transponders are compatible with mode a and mode c secondary surveillance radar ssr systems, in the sense that a mode s interrogator can get replies from mode a and c transponders....ads b is a next generation surveillance method for aircraft that works as a supplement for the traditional radar based system. ads b communication and surveillance further requires identification and selective addressing of aircraft, which is done by ssr and mode s transponder technology. therefore, mode s identification technology supports future air traffic surveillance in the long term.
Question 221-11 : What does the mode s provide information to ?
Ssr and tcas.
In ssr mode s, transponders in aircraft are selectively interrogated by sensors ssr ground stations to perform ranging and bearing as well as to provide enhanced situational awareness with the exchange of binary encoded surveillance information. information from mode s transponders can be received from ssr ground stations which have the capability to interrogate a mode s transponder. tcas systems also rely on the the mode s data link to detect collision hazards and exchange resolution advisories among each other.in ads b, the new standard that has become mandatory in most airspaces by 2020, mode s transponders elicit the periodic or event driven transmission of extended squitters ads b messages in order to provide position, velocity and identity reports to aircraft and ground stations in range.important note we have received multiple feedback supporting the option 'ssr and ads b'. however, latest feedback feb 22 states that the current correct option is 'ssr and tcas', which possibly indicates that this question has been recently updated by easa. please, let us know if you come across this question.
Question 221-12 : You are flying in an area with several ts. you are flying at fl330. what is the best course of action regarding the awr ?
Tilt down as ice crystals at this level are not reflective.
Refer to figure...los 062.03.03.05.02 describe appropriate tilt settings in relation to altitude and thunderstorms...manual tilt management..the tilt refers to the angle between the antenna beam centreline and the horizon. the flight crew should regularly scan the area ahead of the aircraft. in order to identify the strongest weather returns, the flight crew should tilt the weather radar antenna up and down. to obtain a correct display of a storm cell, the flight crew must use the tilt knob to point the weather radar beam to the most reflective part of the storm cell...at high altitude, a storm cell may contain ice particles that have low reflectivity. if the tilt setting is not correct, the nd may display only the upper less reflective part of the storm cell over scanning. as a result, the flight crew may underestimate or not detect a storm cell at all.... . the pilot would normally keep the tilt at 0º to 0.5º down during high altitude cruise. however, if there is a thunderstorm in front, the pilot would want to turn the tilt down significantly, about 5º down to see where the worst part of the storm is and how severe the core of the storm is. we believe this is the point they want to get across in this question.. .... . . . use of the weather radar in accordance with the flight phase. . . . . flight phase. . . tilt control. . . . . taxi. . . away from ground personnel, set the nd to the lowest range – as a rule, set 15º up.. . . . . take off. . . in the case of suspected adverse weather conditions, manually and gradually tilt up to scan weather maximum 15º up. in all other cases, set the tilt to 4º up.. . . . . climb. . . adjust the nd range as required and decrease the tilt angle as the aircraft climbs... generally, set the tilt 5º to 7º up initially, possibly steadily reducing with altitude.. . . . . level flight/cruise. . . adjust the nd range as required. regularly modify the tilt to scan weather ahead of the aircraft. when the weather scan is completed, adjust the tilt so that the ground returns appear on the top of the nd... at high altitude, tilt is set to 0º to 0.5º, except under adverse weather conditions.. . . . . descent. . . set the tilt to about 5º up.. . . . . approach. . . set the tilt to 4º up – which prevents the display of too many ground returns.
Question 221-13 : Mode s transponders can provide vertical tracking by using a altitude increment. ?
25 ft
Vertical performance..mode c provides pressure altitude information in addition to identification and position information compared to mode a. the transponder message is reported in 100 feet increments, which should be considered in terms of vertical separaction by atc...mode s has significantly better performance compared to mode c in terms of updating controller with altitude data. the altitude may be reported with an accuracy of 25 feet.
Question 221-14 : Which of the following statements in reference to the display of aircraft on a primary atc radar is correct ?
Both the range and bearing to the aircraft can be estimated simultaneously.
Refer to figure...primary surveillance radar psr..the psr output data uses polar coordinate system it provides range and bearing of the targets found in respect of the antenna position, these are acquired simultaneously. note that the range is the slant distance from the antenna and not the horizontal distance...the range is determined by the time difference of the emitted and received pulse the speed of propagation is the speed of light and the bearing is obtained from the antenna azimuth. the rotation speed of the antenna is usually between 5 and 12 rpm.
Question 221-15 : What aircraft system will reply to ssr interrogations ?
Mode s transponder
062.03.04.02.09 explain that mode s transponders receive interrogations from tcas and ssr ground stations.the secondary surveillance radar ssr is a surveillance radar system which uses transmitters/receivers interrogators and transponders.the radar antenna rotates and transmits a pulse which is received by the onboard equipment transponder. the transponder sends back a reply containing at least a code if operating in mode a but more often this is combined with level mode c or other information, e.g. aircraft identification, selected level, etc. mode s. the information received depends on the interrogation mode a, c or s and the transponder capability.the ssr relies on the onboard equipment to discover aircraft. in case of transponder failure the ssr will receive no reply and will therefore not discover the target.
Question 221-16 : When in the wx+t mode, what is the airborne weather radar able to detect ?
Turbulence by looking for a frequency shift in combination with pulse flattening.
Wx t mode. this mode stands for weather plus turbulence and enables display of weather targets with turbulence information overlaid on the nd. turbulence is displayed in magenta. the turb function is on most weather radars only active within a range of 40 nm doppler measurement capability and should only be used in wet turbulence.... activating the turbulence mode means the radar will not just be looking at where the return pulses come from and their distance, but also any frequency shift in the returning pulse. if the frequency has changed, then the thing the pulse bounced off must itself be moving which in turn, implies movement of the air, and turbulence. note that pulses must have something to bounce off ideally, large droplets they cannot detect clear air turbulence.
Question 221-17 : The following system s can report an aircraft’s altitude to a precision of 25 feet ?
A mode s transponder.
Vertical performance..mode c provides pressure altitude information in addition to identification and position information compared to mode a. the transponder message is reported in 100 feet increments, which should be considered in terms of vertical separaction by atc...mode s has significantly better performance compared to mode c in terms of updating controller with altitude data. the altitude may be reported with an accuracy of 25 feet.
Question 221-18 : The airborne weather radar awr is displayed on a coloured screen showing the different contours associated with thunderstorms. what procedure should be adopted to avoid a thunderstorm using the awr ?
Fly on the upwind side of the thunderstorm and avoid red or magenta coloured areas.
Airborne weather radardepending on the returning echoes, the reflectivity of the area defines the amount of water droplets present therefore, the differing intensity of expected precipitation is presented to the pilot with colour codes.the painted colours dependent on the water concentration are as follows colourwater concentrationexpected turbulencegreenlightnone or lightyellowmoderatelightredheavymedium or severemagentaheavy or iceseveregenerally speaking, you'll find the best chance for clear, smooth air on the upwind side of a thunderstorm.
Question 221-19 : How will an ssr interrogation be directed toward a specific aircraft ?
With a unique 24 bit address in the interrogation.
062.03.04.02.11 state that every aircraft is allocated an icao aircraft address, which is hard coded into the mode s transponder mode s address..062.03.04.02.12 explain that a 24 bit address is used in all mode s transmissions, so that every interrogation can be directed to a specific aircraft.mode smodes a and c are limited to 4096 available codes. with an increasing volume of air traffic, these systems become prone to interference. mode s was invented to overcome these limitations. 's' stands for selective addressing, which means that a specific aircraft my be interrogated by the controller. one of the main features of mode s is the availability of codes the aircraft address code will be made up of a 24 bit code. considering a 24 bit binary code, it provides over 16 million 224 = 16 777 216 possible hard coded individual addresses to be allocated.mode s differs from modes a and c due to the additional data message up to 112 bits that is transmitted via interrogation.
Question 221-20 : How is the special position identification spi pulse transmitted ?
By the transponder as a result of the pilot pushing the ident button.
The pilot may manually transmit a special position identification spi pulse when the 'ident' button on the pilot's transponder is pressed. the benefit of the squawk 'ident' function is a manual identification of the aircraft. the controller may ask via the radio communication frequency to 'ident' in case of any doubt of identification on the controller display. upon acquisition of the spi pulse, the transponder indication begins to flash on the display of the controller. this produces a distinctive display so that a controller can pick out a particular aircraft by asking the pilot to squawk ident.
Question 221-21 : The information available on an air traffic controller's screen about an aircraft may include 1 from the 2 . ?
1 ground speed 2 ssr
Refer to figure.. in practice the atc uses both the primary and secondary surveillance radar ssr systems together. primary radar is a very useful equipment in determining the aircraft bearing and range, but it has limitations for example if the target is too small, targets can not be directly identified as a specific aircraft no transponder code or the radar signals suffer attenuation due to adverse weather such as storms. for these reasons the atc uses both the primary and secondary radars the ssr supplements the primary radar.when used in conjunction, the primary radar is more accurate in determining the bearing and range of the targets than the ssr, but the ssr provides multitude of additional information the atc controllers are therefore able to see the squawk code transponder code , flight level provided by the transponder in mode c , groundspeed calculated by the ssr ground facility based on the change of bearing and distance of the aircraft and a callsign provided by the transponder in mode s or assigned by the ground facility to a specific squawk code.
Question 221-22 : The crew of a large jet aircraft want to use their airborne weather radar to judge the maximum height of a thunderstorm. their radar display is showing red in the region of the thunderstorm. in order to find the upper level of the thunderstorm, the crew increase the tilt angle of the radar. a ?
Becomes clear in the area of the storm.
Refer to figure...the airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds. the wetter and larger the precipitation, the better the reflectivity, the stronger the returns. wet hail gives the best returns, whereas ice crystals and dry snow do not give good radar returns. stronger returns show up in red, whereas weaker returns are green, and yellow returns in the middle. sometimes magenta is used to show areas of turbulence...the thin pencil beam of the radar scans the area ahead of the aircraft horizontally, and the pilots can choose to manually adjust the vertical tilt of the beam. this can be used to detect the tops or even bases of clouds, given a small diagram and a basic knowledge of trigonometry. the awr will only display returns when it is pointed at an area containing precipitation, in this case a storm cloud. when we tilt the radar beam high enough, it will no longer see the cloud, at which point the returns in that area of the screen will stop, and this is the angle between the aircraft and the top of the cloud...given that we know the range from the storm, which is already on our awr display, we can calculate the relative height of the top of the cloud, and therefore the approximate altitude of the top, using the following formula... cloud tops = range ft x radar tilt angle 1/2 beam width
Question 221-23 : Which of these is one of the main functions of the tilt control on an airborne weather radar system ?
To search for areas of intense precipitation at different levels from the aircraft.
The airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds. the wetter and larger the precipitation, the better the reflectivity, the stronger the returns. wet hail gives the best returns, whereas ice crystals and dry snow do not give good radar returns. stronger returns show up in red, whereas weaker returns are green, and yellow returns in the middle. sometimes magenta is used to show areas of turbulence...the awr is self stabilising at a chosen attitude, using the irs attitude system. it therefore does not respond to aircraft pitch/roll changes, and can be set at a range of desired vertical tilt angles, depending on what the crew want to detect. the tilt settings are usually set high in the climb, to detect weather that is about to be climbed into, low in the cruise, to detect the main cores of weather around, and high again during the descent, to reduce the amount of ground returns that show up on the display. on modern aircraft, there is often an auto tilt setting that is used to relieve pilot workload, but can be overriden for manual tasks...in this question, the best feature is the ability to scan other levels for more/less precipitation, potentially to choose a better level to penetrate precipitation at. it would not be useful to scan clear air above a developing thunderstorm as the cb cloud will continue rising, so this data becomes useless very quickly.
Question 221-24 : Which of the following describes a correct tilt setting for an airborne weather radar ?
During a climb, the tilt needs to be decreased to scan for hazardous clouds.
The airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds. the wetter and larger the precipitation, the better the reflectivity, the stronger the returns. wet hail gives the best returns, whereas ice crystals and dry snow do not give good radar returns. stronger returns show up in red, whereas weaker returns are green, and yellow returns in the middle. sometimes magenta is used to show areas of turbulence... the awr is self stabilising at a particular attitude, using the irs attitude system. it therefore does not respond to aircraft pitch changes, and can be set at a range of desired vertical tilt angles, depending on what the crew want to detect. the tilt settings are usually set high at take off and the beginning of the climb, to detect weather that is about to be climbed into, then reduced during the climb, to spot the more violent cores of weather such as developing thunderstorms that could affect the aircraft. it should be kept low in the cruise, to detect the main cores of weather around, and raised gradually during the descent, to reduce the amount of ground returns that show up on the display.
Question 221-25 : Flying at fl330, ahead of you there are thunderstorms above. which is the proper course of action regarding the tilt of the awr ?
During a climb, the tilt needs to be decreased to scan for hazardous clouds.
The airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds. the wetter and larger the precipitation, the better the reflectivity, the stronger the returns. wet hail gives the best returns, whereas ice crystals and dry snow do not give good radar returns. stronger returns show up in red, whereas weaker returns are green, and yellow returns in the middle. sometimes magenta is used to show areas of turbulence... the awr is self stabilising at a particular attitude, using the irs attitude system. it therefore does not respond to aircraft pitch changes, and can be set at a range of desired vertical tilt angles, depending on what the crew want to detect. the tilt settings are usually set high at take off and the beginning of the climb, to detect weather that is about to be climbed into, then reduced during the climb, to spot the more violent cores of weather such as developing thunderstorms that could affect the aircraft. it should be kept low in the cruise, to detect the main cores of weather around, and raised gradually during the descent, to reduce the amount of ground returns that show up on the display.
Question 221-26 : The control panel of an airborne weather radar awr has a knob for adjusting the gain, what is its purpose ?
To adjust the sensitivity of the radar receiver.
Weather radar operation..the flight crew uses four features to operate the radar... antenna tilt this is the angle between the centre of the beam and the horizon.. range control of the nd this also has an essential influence on the optimum tilt setting.. gain control this adjusts the sensitivity of the receiver.. radar modes weather wx or weather + turbulence wx + t...gain is simply a control of how much of a return the awr airborne weather radar needs to pick up before it shows it on the display. it is the sensitivity, and can be adjusted as required to see the areas of worst precipitation, and see exactly how bad they are on a case by case basis.
Question 221-27 : On the control panel for an airborne weather radar, there is a setting called map , what is the function of this setting ?
To change the shape and orientation of the transmission beam down toward the ground.
Refer to figure...learning objective 062.03.03.06.01 describe the navigation function of the radar in the mapping mode...the airborn weather radar awr has two different uses, the primary one is of course to spot the areas of precipitation around the front of the aircraft to allow the pilots to avoid any dangerous areas of weather...the secondary use consists of tilting the awr more downwards below the horizon, where it will look for reflections from the nearby land. this is the mapping mode, and the awr actually has a separate beam transmission pattern that is best suited to receive accurate ground returns. this can be used for navigation, especially when dealing with coastlines and islands, etc. it used to be a very useful tool, but is less useful in the modern era due to gps systems and moving map displays.
Question 221-28 : Which of the following types of interrogations will a mode s transponder reply to ?
Ssr and tcas interrogations.
Learning objective 062.03.04.01.03 state that an airborne transponder provides coded reply signals in response to interrogation signals from the ground secondary radar and from aircraft equipped with traffic alert and collision avoidance system tcas....mode s transponders are a natural continuation of the mode a and mode c transponders. the mode a transponder is able to sent a 4 digit squawk code, of which there are only 4096 individual identities, mode s can handle 16 million different icao 24 bit aircraft addresses aas. these aas are unique addresses registered to a particular aircraft. there is also a much larger ability for transfer of information through mode s, with many different aircraft parameters able to be transferred to the ground through els elementary surveillance or ehs enhanced surveillance systems, and even a capacity of communications via datalink...mode s transponders use the same frequencies as mode a/c transponders, so are backwards compatible, and the ssr ground station produces different interrogation pulses to require a response from a particular mode s transponder or can 'all call' mode s transponders...the mode s transponder also receives information from tcas interrogations from nearby aircraft, and replies with information such as range, bearing and altitude to aid tcas separation. mode s transponders are key to tcas operation, and are very closely linked...the other options in these answers could not be correct. in primary radar, there is a reflection, not a reply. ads b is a system which relies on un requested output signals from the aircraft's transponder, called squitters. these squitters also aid tcas identification.
Question 221-29 : In what ways can information from a typical airborne weather radar from a modern jet transport aircraft built from around 2010 onwards be used to assist the pilots whilst navigating along a route ?
Paths through areas of weather may be determined to ensure the safety and comfort of the flight.
Learning objective 062.03.03.06.03 explain how turbulence not cat can be detected by a modern weather radar...airborne weather radars have 2 main functions, weather detection and ground mapping...pilots look ahead using their awr to pick the a route using areas of best weather and least turbulence. turbulence can be detected by modern awrs, but not all areas of turbulence, as cat clear air turbulence has no associated particles which can reflect radar pulses it is invisible by definition...standard turbulence within clouds can be detected, as the movement of the precipitation within the cloud causes a doppler shift on the returning radar pulses, so the radar can form an idea of the air movement patterns in that area. if they are erratic, then turbulence exists in that region...this question is not referring to the mapping mode. for one, the mapping mode has been used for over 70 years, so is not only used in 'modern' weather radars. also, the mapping is not very good at displaying mountainous terrain, and would never be used for such applications. it would also be very difficult to navigate via ground feagtures using it over the clouds, as the clouds would reflect many pulses, making it innacurate.
Question 221-30 : The secondary surveillance radar ssr system used by aircraft transponders is based on the transmission of 1 from the atc secondary radar and 2 from the airborne transponder. ?
1 interrogations 2 replies
Learning objective 062.03.04.01.01 state that the atc system is based on the replies provided by the airborne transponders in response to interrogations from the atc secondary radar.unlike a primary radar system, which sends out pulses and then waits for any of those pulses to be reflected off an item such as an aircraft, a secondary surveillance radar ssr sends out pulses, which are interrogations of aircraft ssr transponders. the interrogation is sent out of frequency 1030 mhz, and the aircraft transponder then emits its own string of reply pulses on 1090 mhz, a different frequency.this method of radar usage has many benefits, as the signals only need to be a quarter as powerful to travel half the distance, primary radar signals have to travel to and object and then return to the station, whereas with ssr, the reply signals are freshly produced by the aircraft transponder, so cover the air to ground journey, reducing the required power of the radar.ssr also has the benefits of being able to transmit a series of encoded pulses, giving a 4 digit transponder squawk code of an aircraft in mode a operation, and a pressure altitude readout when also using mode c. more data can be sent out by mode s also, and this is all encoded into strings of reply pulses emitted by the aircraft transponder.
Question 221-31 : In general the operation of an aircraft's airborne weather radar awr whilst on the ground is ?
Only permitted whilst following certain precautions, to safeguard health of ground personnel and to protect equipment.
062.03.03.04.01 explain why awr should be used with extreme caution when on the ground...airborne weather radar awr systems produce a powerful beam of electromagnetic radiation at a frequency of 9 10 ghz, which means that it is microwave radiation. microwave radiation is hazardous to organic material as it heats up water molecules and fats very quickly, exactly the same as in a microwave oven. this can cause tissue damage if exposed in high quantities...this is the reason that awrs should be switched off when on the ground, unless proper precautions have been taken to avoid the ground crew being exposed to the radiation, for testing, etc.
Question 221-32 : A young adult interested in becoming a pilot is invited into the cockpit. they are interested in the weather radar and ask the pilot why there is a tilt knob on the control unit. the pilot replies that this to control the upwards and downwards tilt of the antenna, as required for the two main tasks ?
Detecting significant weather and ground mapping.
Learning objective 062.03.03.01.01 list the two main tasks of the weather radar in respect of weather and navigation...the trick with this question is to translate it into the relevant parts immediately. the examiner has written a story to increase confusion and test the candidate's ability to pick out important information, which also happens in lots of other atpl questions...this question can be translated into 'what are the two main tasks of the airborne weather radar '. the two main tasks of the airborne weather radar awr see learning objective above are detecting significant weather in order to avoid it and to use for ground mapping which used to be very common use of the awr but is less used these days...the question also mentions the tilt control knob but does not actually ask a question related to it, it is just part of the story.
Question 221-33 : Some of the advantages of secondary surveillance radar ssr in comparison to primary radar are that ssr 1 and has a longer range because 2 . ?
1 collects more data 2 of the active participation of the aircraft's transponder
Learning objective 062.03.04.01.04 state the advantages of secondary surveillance radar ssr over a primary radar regarding range and collected information due to transponder principal information and active participation of the aircraft.unlike a primary radar system, which sends out pulses and then waits for any of those pulses to be reflected off an item such as an aircraft, a secondary surveillance radar ssr sends out pulses, which are interrogations of aircraft ssr transponders. the interrogation is sent out of frequency 1030 mhz, and the aircraft transponder then emits its own string of reply pulses on 1090 mhz, a different frequency.this method of radar usage has many benefits, as the signals only need to be a quarter as powerful to travel half the distance, primary radar signals have to travel to and object and then return to the station, whereas with ssr, the reply signals are freshly produced by the aircraft transponder, so cover the air to ground journey, reducing the required power of the radar... ssr also has the benefits of being able to transmit a series of encoded pulses, giving a 4 digit transponder squawk code of an aircraft in mode a operation, and a pressure altitude readout when also using mode c. more data can be sent out by mode s also, and this is all encoded into strings of reply pulses emitted by the aircraft transponder.
Question 221-34 : The tilt of an airborne weather radar is lowered whilst searching for thunderstorms in high level cruise flight. why is that ?
The greatest reflectivity occurs from wet hail and rain, these elements usually exist in the lower levels of a thunderstorm.
Refer to figure...los 062.03.03.05.02 describe appropriate tilt settings in relation to altitude and thunderstorms...airborne weather radar..an airborne weather radar is designed for avoiding severe weather, not for penetrating it. awr detects drops of precipitation such as rain and wet hail...at high altitude, a storm cell may contain ice particles that have low reflectivity. if the tilt setting is not correct, the nd may display only the upper less reflective part of the storm cell over scanning. as a result, the flight crew may underestimate or not detect a storm cell at all.... the pilot would normally keep the tilt at 0º to 0.5º down during high altitude cruise. however, if there is a thunderstorm in front, the pilot would want to turn the tilt down significantly, about 5º down to see where the worst part of the storm is and how severe the core of the storm is..... . . use of the weather radar in accordance with the flight phase. . . flight phase. tilt control. . . taxi. away from ground personnel, set the nd to the lowest range – as a rule, set 15º up.. . . take off. in the case of suspected adverse weather conditions, manually and gradually tilt up to scan weather maximum 15º up. in all other cases, set the tilt to 4º up.. . . climb. adjust the nd range as required and decrease the tilt angle as the aircraft climbs... generally, set the tilt 5º to 7º up initially, possibly steadily reducing with altitude.. . . level flight/cruise. adjust the nd range as required. regularly modify the tilt to scan weather ahead of the aircraft. when the weather scan is completed, adjust the tilt so that the ground returns appear on the top of the nd... at high altitude, tilt is set to 0º to 0.5º, except under adverse weather conditions.. . . descent. set the tilt to about 5º up.. . . approach. set the tilt to 4º up – which prevents the display of too many ground returns.
Question 221-35 : What is shown on the atc radar screen when the pilot pushes the special position identification spi button on the transponder ?
A flashing indication of the aircraft which is 'squawking ident'.
Learning objective 062.03.04.02.07 state that in addition to the information provided, on request from atc, a special position identification spi pulse can be transmitted but only as a result of a manual selection by the pilot ident button....the pilot may manually transmit a special position identification spi pulse when the 'ident' button on the pilot's transponder is pressed. the benefit of the squawk 'ident' function is a manual identification of the aircraft. the controller may ask via the radio communication frequency to 'ident' in case of any doubt of identification on the controller's display. upon acquisition of the spi pulse, the indication of that aircraft begins to flash on the display of the controller. this produces a distinctive display so that a controller can pick out a particular aircraft by asking the pilot to squawk ident. it is one of the many ways that controllers can link an aircraft on frequency to one on their radar display...note this question has been created from incomplete feedback, so any further information, particularly about the 4 options, would be useful to refine the question, thank you.
Question 221-36 : What is the primary use of the radar fitted onboard a modern civilian transport aircraft ?
Detecting areas of wet, convective weather.
Radar has many uses in the world, in aviation, primary radar can be used to spot aircraft and weather, but in the air, aircraft tend to use it for just weather information. that is why all large aircraft are equipped with an airborne weather radar...the airborne weather radar awr system fitted on large aircraft uses a primary radar system to look for reflections from precipitation in clouds. the wetter and larger the precipitation, the better the reflectivity, the stronger the returns. wet hail gives the best returns, whereas ice crystals and dry snow do not give good radar returns. stronger returns show up in red, whereas weaker returns are green, and yellow returns in the middle. sometimes magenta is used to show areas of turbulence. convective weather has bigger, wetter precipitation, which makes for stronger radar returns...the radar works the same as any other pulse radar, by pointing in a particular direction and firing off a pulse of electromagnetic radiation in the microwave band , then waiting for a reply from any potential reflections in that area. it then measures the time of arrival of the reflection, and uses this to calculate the distance from the target as the pulses travel at the speed of light...collision detection such as tcas is usually provided through secondary radar, with pulses and replies, rather than reflections.
Question 221-37 : Radar has many uses in civil aviation. for which tasks are both primary and secondary radar used ?
For atc to provide tracking of aircraft and manage traffic within a given airspace.
Note this question is asking about primary and secondary radar, not just one, but when are both used...learning objective 062.03.01.01.01 name the different applications of radar with respect to air traffic control atc , weather observations, and airborne weather radar awr....radar is an incredibly useful tool to aviation, and is used in many forms, for multiple different jobs in civil aviation...for starters, it is split into primary and secondary radar. primary radar is where a transceiver sends out electromagnetic pulses or waves that are reflected off items in the environment, back to the transceiver, and the time taken to travel to and from the object is measured, to give an indication of its range. the radar scans back and forth to figure out the direction of the object, and in doing so, gets a direction and distance, so can plot the location on a display...secondary radar is where an interrogator sends out an interrogation signal, transponders pick this signal up, then send a reply signal, which is good as it can carry more information, such as squawk codes and altitudes, as used in ssr secondary surveillance radar....atc can use primary radar to track aircraft and weather, and use secondary radar also to track aircraft and gain extra information about an aircraft ssr...pilots can use primary radar to track weather and navigate airborne weather radar as well as in the radio altimeter, and can use secondary radar to detect other aircraft for collision avoidance acas/tcas , as well as for dme which is technically a secondary radar system, the aircraft is the interrogator.
Question 221-38 : A mode s transponder knows that it is receiving interrogations from a mode s ground interrogator because ?
Extra pulses are transmitted directly following the mode a and mode c pulses.
Mode s does not transmit the p3 pulse, but has an additional p4 pulse. transponder without mode s will ignore p4 impulses. p4 pulses can be either long or short in duration...the mode a/c/s all call interrogation elicits a mode a or mode c reply depending on the p1 p3 pulse spacing from a mode a/c transponder because it does not recognize the p4 pulse. a mode s transponder recognizes the long p4 pulse and responds with a mode s reply. icao annex 10 aeronautical telecommunications, chapter 3..this means that a mode s transponder transmits or receives extra pulses after the mode a and mode c transponder pulses.
Question 221-39 : The pilot is given a 25 ft altitude increment. which ssr mode does this apply to ?
Mode s
Vertical performance..mode c provides pressure altitude information in addition to identification and position information compared to mode a. the transponder message is reported in 100 feet increments, which should be considered in terms of vertical separaction by atc...mode s has significantly better performance compared to mode c in terms of updating controller with altitude data. the altitude may be reported with an accuracy of 25 feet.
Question 221-40 : A primary surveillance radar psr is capable of calculating a... ?
Two dimensional position by measuring the bearing and travel time of the interrogation signal.
Refer to figure.. primary surveillance radar psr primary surveillance radar psr operates by emitting radio wave pulses from a rotating antenna. when these pulses encounter an aircraft or object, some of the energy is reflected back to the antenna. the psr uses a polar coordinate system to provide information on the detected targets. it calculates the range, which is the slant distance from the antenna to the target, and the bearing, which is determined by the antenna's azimuth.range. the range is determined by comparing the time it takes for the pulse to be emitted and received, utilizing the speed of light as the propagation speed. it's important to note that the range provided is not the horizontal distance, but the slant distance from the antenna to the target.bearing. the measurement of bearing is achieved using the searchlight principle. this involves concentrating radio pulses into narrow beams, which can be accomplished by either shortening the wavelength or increasing the size of the aerial in advanced systems, this is done electronically. the narrow beam is then rotated at a constant speed. when an echo is received, the direction of the object is determined based on the direction of the beam at the time of receiving the echo. this direction is measured from a fixed reference point or datum.primary surveillance radar psr calculates bearing and range time difference of a target providing a two dimensional position.
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