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Question 207-1 : What beam is used in the mapping mode of an airborne weather radar that can utilise two different beam shapes ? [ Exam pilot ]

A cosecant squared beam effective up to a maximum of 50 nm to 60 nm

The radar can has two modes weather and mapping the weather beam is used for detecting clouds and is a conical pencil beam with a width of 5 degrees and the mapping is for ground features and uses a fan shaped or cosecant squared beam .the directional properties of the radar produce side lobes one side lobe goes vertically down to the ground and is received back by the weather radar receiver this received signal produces a height ring on the display the ring indicates that the radar is working and appears at the approximate height of the aeroplane above the gound an aeroplane flying at 12000ft will have a permanent return at approximately 2nm .weather radars produce a wide fan shaped beam cosecant square beam by placing parasitic elements in front of the radar dish to deflect the beam it is also referred to as the spoil beam the cosecant square beam provides a wider coverage than the conical beam at short range and its transmission pattern has the effect of compensating for range by sending more power to the top part of the beam which hits more distant objects the cosec beam works out to between 60nm and 150nm depending on type this is probably an old question that’s why the correct answer is from 50nm to 60 nm only beyond that range there is not enough power in the beam to produce reasonable returns so the more concentrated conical beam should be used instead in the weather mode the radar display of ground returns does not always look like the terrain would look like on a map hills can cause 'shadowing' at low altitude masking the terrain behind them and giving a false impression of water in arctic regions returns from ice can mask the true shape of the coastline exemple 307 A cosecant squared beam effective up to a maximum of 50 nm to 60 nm.

Question 207-2 : Ground secondary surveillance radar ssr equipment incorporates a transmitter and receiver that operate in the following frequencies ?

Transmits on 1030 mhz and receives on 1090 mhz

A secondary surveillance radar ssr system uses transmitters/receivers interrogators and transponders a pulse coded interrogation message is sent from the ground to the aircraft the transponder responds in accordance with the pulse coded interrogation in the form of a pulse train that is a series of pulses which carry the appropriate information the transmissions are achieved in the uhf band where all ground interrogation pulses are processed at a 1 030 mhz carrier frequency and all transponder responses are completed on the 1 090 mhz carrier channel .. . ground transmits on 1030 mhz and receives from aircraft on 1090 mhz exemple 311 Transmits on 1030 mhz and receives on 1090 mhz.

Question 207-3 : Ignoring pulse length the maximum pulse repetition frequency prf that can be used by a primary radar facility to detect targets unambiguously to a range of 200 nm is… pps = pulses per second ?

405 pps

Prf pulse recurrence frequency is the number of pulses trasmitted in a second . .prf is one of the main factors that determine the maximum theoretical unambiguous range of a pulse radar . .the trasmitter must remain silent while the receiver is listening for echoes . .if the design maximum range is 200nm the receiver must be allowed to listen for the period of time fro when a pulse has been trasmitted untill it can go to 200nm and than return . .that is a round trip of 400 nm which would require a longer silent period than a radar whit a range of 100nm where the pulses have to travel only 200nm . .therefore we can say that a lower prf enables a longer maximum theoretical range max therorical range is inversly proportional to the prf .the following formula may be used to calculate the max theoretical unambiguous range .range in km = 300 000 ÷ prf x 2 or if we need to find the required prf based on a specific unambiguous range needed we can rearrange the formula . .prf = 300 000 ÷ range in km x 2 .in our case we can apply the second one . .1 nm = 1 852 km so . .200 x 1 852 = 370 4 km.prf = 300 000 ÷ 370 4 x 2 . .prf = 404 97 pps = approx 405 pps exemple 315 405 pps.

Question 207-4 : To double the effective range of a primary radar the power output must be increased by a factor of ?

16

Primary surveillance radar psr works on the echo principle that uses strong transmitted signals at a known time these signals reflect from objects and the echoes are detected psr theoretical range depends among others on the power output of the radar transmitter .. range nm =4 power w . if we double the range the power output required increases by 16 exemple 319 16.

Question 207-5 : The prime factor in determining the maximum unambiguous range of a primary radar is the ?

Pulse repetition frequency

Pulse repetition frequency prf is the number of occurrences pulses each second the prf has a large significance on maximum range depending on how far the radar wishes to search for objects and what the visible range is the pulse repetition interval has to be set in a way to always allow the pulse to reach the range limits and return .the maximum theoretical unambiguous range is calculate by the formula .. range km = 300 000 ÷ prf × 2 ..in the above formula the range is given in kilometres and the prf is in pps the formula includes '300 000' which represents the number of km the light travels every second speed of light .note the minimum detection range of a pulse radar is determined primarily by the pulse length/width exemple 323 Pulse repetition frequency.

Question 207-6 : Airborne weather radars are generally based on the use of ?

Primary radar in the shf band

Airborne weather radar awr is a primary radar system that is fitted to an aeroplane the selected frequency for awr is in the shf band and is 9 375 ghz this has an associated wavelength of 3 2 cm awr must be optimised not to detect very small particles such as thin fog but to accurately identify rain particles in storms .. too small wavelengths will result in reflection from very small particles larger wavelengths result in the waves bending around particles of interest exemple 327 Primary radar in the shf band.

Question 207-7 : Which of the following types of radar equipment operate by means of the pulse technique .1 aerodrome surface movement radar . .2 airborne weather radar . .3 secondary surveillance radar ssr . .4 aerodrome surveillance approach radar ?

1 2 3 and 4

The pulse technique works by the transmission of pulse modulated signals the pulses are short interval high energy electromagnetic emissions this method is used by .. distance measuring equipment dme interrogator/transponder principle. secondary surveillance radar ssr interrogator/transponder principle. atc area or terminal surveillance radar echo / reflection principle . airport surface movement radar echo/reflection principle. airborne weather radar awr echo principle exemple 331 1, 2, 3 and 4

Question 207-8 : Which of the following phenomena is least likely to be detected by radar ?

Clear air turbulence

Conventional weather radar cannot detect wind speed or turbulence directly it only detects solid and liquid objects above a threshold size the most turbulent areas of thunderstorms are also those areas that contain the most water and ice note that the areas in which the concentration of droplets decreases rapidly which are marked on the radar screen by a sharp fall in signal intensity are normally areas in which the most severe turbulence can be encountered these are areas in which the strong up going air currents are in close proximity to downward flowing currents and there is a strong risk of severe vertical wind shear these areas will be identified on the radar screen by a rapid change in appearance of the cloud return steep change in colors of the return steep color gradient if you identify this area on your radar screen avoid that area .* green light precipitation slight turbolence.* yellow or amber medium precipitation light turbolence.* red heavy precipitation medium to severe turbolence.* magenta extremely high precipitation severe turbolence.so the weather radar is merely detecting the presence of water it is the pilot interpreting the picture who is really detecting the turbulence .clear air turbulence cat does not have condensated water in it and is therefore undetectable by conventional radar there are systems such as lidar that can detect cat but they generally not installed on aircraft exemple 335 Clear air turbulence

Question 207-9 : What equipment works on the interrogator/transponder principle ?

Secondary surveillance radar ssr

A secondary surveillance radar ssr system uses transmitters/receivers interrogators and transponders a pulse coded interrogation message is sent from the ground to the aircraft the transponder responds in accordance with the pulse coded interrogation in the form of a pulse train that is a series of pulses which carry the appropriate information the transmissions are achieved in the uhf band where all ground interrogation pulses are processed at a 1 030 mhz carrier frequency and all transponder responses are completed on the 1 090 mhz carrier channel exemple 339 Secondary surveillance radar (ssr)

Question 207-10 : If the airborne weather radar system is fitted with an auto tilt function what does that mean the radar antenna tilt is automatically adjusted ?

Based on the altitude of the aircraft

Modern aircraft are equipped with an automatic tilt function which sets the antenna tilt based on aircraft position altitude and range in weather mode the tilt is set to be above any terrain ahead based on the worldwide navigation database which supplies elevation data to the awr management computer exemple 343 Based on the altitude of the aircraft.

Question 207-11 : To improve the detection of precipitation area s in e g thunderstorms in which the top of the cloud lies at or slightly above the level of flight the tilt setting should be ?

Lower when the aircraft climbs to a higher altitude

If we know of the presence of thunderstorms then tilting the radar can be very useful to gather information about the strength of the thunderstorm and the levels at which it is worst .if we are at a level just below the top of the thunderstorm it is likely that we have the tilt set to 0 or even 1 or 2 degrees in order to see the more violent lower section of the thunderstorm if we climb higher perhaps to overfly the storm then that same tilt setting will be looking higher up within the storm and will be seeing the ice crystals rather than the wet hail and large water droplets this is why we would set the tilt further downwards after making such a climb .it is important to remember that there are other questions asking about the tilt setting during take off and climb out well of course the setting at that time of flight would be quite high to see the weather the aircraft is climbing towards and avoid clutter from ground returns after that though the tilt setting should gradually be reduced until the cruise and then in the descent gradually increased again to avoid ground returns .remember also that the radar is automatically stabilised so it follows the horizon plus/minus any tilt not the aircraft attitude plus/minus tilt exemple 347 Lower when the aircraft climbs to a higher altitude.

Question 207-12 : When using airborne weather radar in the mapping mode in polar areas one runs the risk of ?

Mistaking the edge of coastal ice off shore for the real coastline

Mapping mode is very useful to provide basic orientation relative to significant terrain features it may be used to distinguish land from water by detecting coastlines in map mode the receiver sensitivity is decreased to accomodate terrain characteristics instead of weather this mode enables identification of terrain features such as mountains coastlines bodies of water etc however it is important to note that off shore ice blocks may be mistaken for the real coastline with black areas in between being mistaken for the shadowed lee side of mountains exemple 351 Mistaking the edge of coastal ice off shore for the real coastline.

Question 207-13 : In order to provide an air traffic services ats surveillance service what minimum information must be provided to the controller on the surveillance system display indication of position and also ?

Any map information needed to provide the surveillance service and when available the aircraft identification and level

To provide air traffic services ats surveillance service the minimum required information is .. position and. map information which serves as a reference to airspace structure .. if the aircraft is equipped with a transponder depending on the mode of operation additional information may be provided .. mode a provides solely 2d position information that is presented on the screen of the controller in the horizontal plane . mode c 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 provides data transmission as well which contains further aircraft derived data exemple 355 Any map information needed to provide the surveillance service, and (when available) the aircraft identification and level.

Question 207-14 : What are the potential dangers of operating an airborne weather radar awr on the ground radiated energy can ?

Harm human beings

Avoid weather radar awr operation when personnel are within the area normally enclosed by the aircraft nose radome these radars can be the most dangerous critters in the cockpit awr work on super high freqencies shf to do what they do and without proper care that energy can be hazardous to you and others around the airplane i e tissues getting damaged exemple 359 Harm human beings.

Question 207-15 : What is an advantage of an ssr with a ‘selective addressing mode’ over primary radar ?

It allows for unambiguous aircraft identification

Mode s.modes 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 may be interrogated by the controller with selective addressing signal interference is avoided further ensuring system accuracy exemple 363 It allows for unambiguous aircraft identification.

Question 207-16 : When using awr in the climb what should be done ?

Tilt down

Refer to figure manual tilt managementthe 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 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 exemple 367 Tilt down

Question 207-17 : What is the difference between a/c all call and a/c/s all call ?

Duration of p4 pulse

Refer to figure .mode a/c all call consists of p1 p2 p3 and short p4 .mode a/c and s consists of p1 p2 p3 and long p4 .. . as you can see in the attached diagram the difference lies in the duration of p4 pulses exemple 371 Duration of p4 pulse.

Question 207-18 : Which statement is correct regarding the airborne weather radar and it autotilt function ?

It adjusts its tilt according to the altitude

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 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 . ..early generation of full manual controlled radars were without auto tilt .honeywell introduced the first weather radar featuring with an automatic tilt computation named autotilt .when in autotilt mode the radar uses the egpws terrain database and automatically adjusts the antenna tilt based on the aircraft position altitude and the selected nd range fig 6 .the next generation of radars fully automatic radars optimize weather detection and decrease significantly the pilots’ workload necessary to understand the complete picture of the weather ahead they included automatic functions which .. . scan airspace ahead of the aircraft with multiple beams. . . feature a three dimensional 3d buffer to store weather data. . . automatically compute and adjust the antenna tilt. . . offer independent pilot control and display selection . ..this kind of radars automatically adjusts the gain and tilt based on various parameters aircraft altitude geographical area season time of the day to obtain the best weather display in each geographic region exemple 375 It adjusts its tilt according to the altitude.

Question 207-19 : Which of the following statements is correct about the 'gain' knob of an awr ?

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 exemple 379 It adjusts the receiver sensitivity in order to achieve optimum target acquisition.

Question 207-20 : 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 exemple 383 Atc ssr systems can interrogate aircraft transponders and elicit replies.

Question 207-21 : 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 exemple 387 Rainfall intensity.

Question 207-22 : 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 exemple 391 This is normal since with decreasing range the beam width azimuth will also decrease.

Question 207-23 : 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 exemple 395 A cloud behind another cloud which cannot be detected.

Question 207-24 : 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 exemple 399 Fly on the upwind side of the storm, avoiding red and magenta coloured areas on the screen.

Question 207-25 : 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 exemple 403 Ssr ground station and tcas.

Question 207-26 : 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

exemple 407 1, 2, 3, and 4.

Question 207-27 : 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 exemple 411 The weather conditions are unknown.

Question 207-28 : 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 exemple 415 (1) ssr modes a and c; (2) automatic dependent surveillance - broadcast (ads-b).

Question 207-29 : 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 exemple 419 Ssr and tcas.

Question 207-30 : 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 exemple 423 Tilt down as ice crystals at this level are not reflective.

Question 207-31 : 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 exemple 427 25 ft

Question 207-32 : 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 exemple 431 Both the range and bearing to the aircraft can be estimated simultaneously.

Question 207-33 : 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 exemple 435 Mode s transponder

Question 207-34 : 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 exemple 439 Turbulence by looking for a frequency shift in combination with pulse flattening.

Question 207-35 : 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 exemple 443 A mode s transponder.

Question 207-36 : 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 exemple 447 Fly on the upwind side of the thunderstorm and avoid red or magenta coloured areas.

Question 207-37 : 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 exemple 451 With a unique 24-bit address in the interrogation.

Question 207-38 : 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 exemple 455 By the transponder as a result of the pilot pushing the ident button.

Question 207-39 : 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 exemple 459 (1) ground speed; (2) ssr

Question 207-40 : 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 exemple 463 Becomes clear in the area of the storm.


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