Question 218-1 : Which combination of characteristics gives best screen picture in a primary search radar ? [ Preparation civilian ]

Question 218-2 : The minimum range of a primary radar using the pulse technique is determined by the i the maximum unambiguous range by the ii ?

I pulse length ii pulse recurrence frequency.

Question 218-3 : The maximum range of primary radar depends on ?

Pulse recurrence frequency.

Primary radar provides bearing and distance of targetsprimary ground radar is used to detect aircraft that are not equipped with a secondary radar transponderthe maximum theoretical unambiguous range if the prf is given using the formula range in km = 300000 prf x 2 prf pulse repetition frequency take care pulse length defines the minimum theoretical range of a radar

Question 218-4 : A frequency of airborne weather radar is ?

9375 mhz.

The wavelength is approximately 3 cm and frequency of most airborne weather radar awr is approximately 9 ghz

Question 218-5 : Under easa cs 25 colour code rules for electronic flight instrument systems efis increasing intensity of precipitation are coloured in the order ?

Green amberyellow red magenta.

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Question 218-6 : For any given circumstances in order to double the effective range of a primary radar the power output must be increased by a factor of ?

16.

To increase the range of a radio transmission the power is increased by a square factor to double its range the power is increased by a 4 factor x2² but for a primary radar signal must return to the ground station in order for the radar to workpower output must be increased by a factor of 2²x 2² = 16

Question 218-7 : A weather radar set to the 100 nm scale shows a squall at 50 nm by changing the scale to 50 nm the return on the radar screen should ?

Increase in area and move to the top of the screen.

2617by changing the scale to 50 nm the squall line increases in area and moves to the top of the screen

Question 218-8 : The code transmitted by a ssr transponder consists of ?

Pulses.

Question 218-9 : In which frequency band do most airborne weather radars operate ?

Shf.

Vor operating frequencies vhflocaliser vhfmarker beacon vhfdme operating frequencies uhfglide slope uhfgnssgps uhfl1 and l2 frequencies used by navstargps uhfils localiser and glide slope vhf and uhf bandsmicrowave landing system mls shfairborne weather radars shflocator lfmf

Question 218-10 : The maximum range of an en route radar is approximately ?

200 300 nm.

An aircraft at flight level 410 41000 ft can be seen by a long range radar located at mean sea level at 123*sqrt41000 = 250 nm sqrt square root

Question 218-11 : In airborne weather radar awr the main factors which determine whether a cloud will be detected are ?

Size of the water drops wavelengthfrequency used.

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Question 218-12 : In order to ascertain whether a cloud return on an aircraft weather radar awr is at or above the height of the aircraft the tilt control should be set to assume a beam width of 5° ?

25° up.

An aircraft weather radar awr is typically located in the nosecone of the aircraft behind a radome that is composed of non reflective materialincorporated in the cockpit equipment is a tilt feature either automatic or manual which enables the crew to raise or lower the sweep above and below the longitudinal axis of the aircraftwhen assessing the intensity of a thunderstorm the tilt should be adjusted to the middle and lower portions of the system where the density of precipitation provides the most accurate indications of size and intensity 2619

Question 218-13 : In relation to radar systems that use pulse technology the term pulse recurrence rate prr signifies the ?

Number of pulses per second.

Question 218-14 : What is the maximum number of usable secondary surveillance radar ssr transponder codes in mode a ?

4096.

Squawk codes are four digit octal numbers the dials on a transponder read from 0 to 7 inclusivethus the lowest possible squawk is 0000 and the highest is 7777 four octal digits can represent up to 4096 different codes

Question 218-15 : Which of the following equipments uses primary radar principles ?

Airborne weather radar awr .

Radar is a distance measuring system using the principle of radio echoing the term radar is an acronym for radio detecting and ranging it is a method for locating targets by using radio waves the transmitter generates microwave energy in the form of pulses these pulses are then transferred to the antenna where they are focused into a beam by the antenna the radar beam is much like the beam of a flashlight the energy is focused and radiated by the antenna in such a way that it is most intense in the center of the beam with decreasing intensity near the edge the same antenna is used for both transmitting and receiving when a pulse intercepts a target the energy is reflected as an echo or return signal back to the antenna from the antenna the returned signal is transferred to the receiver and processing circuits located in the receiver transmitter unit the echoes or returned signals are displayed on an indicatorthis is the same principle uses for an airborne weather radar

Question 218-16 : Which of the following equipments works on the interrogatortransponder principle ?

Secondary surveillance radar ssr .

Question 218-17 : In order to indicate an emergency situation the aircraft secondary surveillance radar ssr transponder should be set to ?

7700.

7600 radio communication failure7500 unlawful interference with the planned operation of the flight7700 emergency situation

Question 218-18 : The theoretical maximum range for an airborne weather radar is determined by the ?

Pulse recurrence frequency.

Question 218-19 : The selection of code 7500 on an aircraft ssr transponder indicates ?

Unlawful interference with the planned operation of the flight.

7500 unlawful interference with the planned operation of the flight7600 radio communication failure7700 emergency situation

Question 218-20 : The selection of code 7700 on an aircraft ssr transponder indicates ?

An emergency.

7700 emergency situation7600 radio communication failure7500 unlawful interference with the planned operation of the flight

Question 218-21 : In a primary radar using pulse technique pulse length determines ?

Minimum measurable range.

Pulse length defines the minimum theoretical range of a radarpulse repetition frequency prf gives the maximum theoretical unambiguous range of the radar range in km = 300000 prf x2 if you search for the prf prf = 300000 range in km x 2

Question 218-22 : In a primary radar using pulse technique pulse recurrence frequency determines ?

Maximum theoretical range.

Pulse length defines the minimum theoretical range of a radarpulse repetition frequency prf gives the maximum theoretical unambiguous range of the radar maximum theoretical range = velocity of light 2 x pulse repetition frequency

Question 218-23 : Which of the following radar equipments 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.

Pulse technique radar involves the transmission of pulses of electromagnetic waves by means of a directional antenna some of the pulses are reflected by objects that intercept them the reflections are picked up by a receiver processed electronically and converted into visible form by means of a cathode ray tube the range of the object is determined by measuring the time it takes for the radar signal to reach the object and return the object's location with respect to the radar unit is determined from the direction in which the pulse was received in most radar units the beam of pulses is continuously rotated at a constant speed or it is scanned swung back and forth over a sector also at a constant rate the velocity of the object is measured by applying the doppler principle if the object is approaching the radar unit the frequency of the returned signal is greater than the frequency of the transmitted signal if the object is receding from the radar unit the returned frequency is less and if the object is not moving relative to the radar unit the return signal will have the same frequency as the transmitted signalaerodrome surface movement radar airborne weather radar secondary surveillance radar ssr and aerodrome surveillance approach radar operate by means of the pulse technique

Question 218-24 : On which of the following radar displays is it possible to get an indication of the shape and to some extent the type of the aircraft generating the return ?

Aerodrome surface movement radar asmr .

Surface movement radar smr systems are used by air traffic controllers to detect and guide aircraft and vehicles ie baggage carriers buses supply trucks staff cars etc on the ground surface of the airport and thus secure safety it is the most widely used surveillance system for airport surveillance at presentit is sometimes possible to identify aircraft types from the return

Question 218-25 : Which of the following lists the phenomena least likely to be detected by radar ?

Clear air turbulence.

The weather radar only detects precipitation dropletshow much it detects depends upon the size composition and number of droplets water particles are five times more reflective than ice particles of the same sizethe radar does detect rainfall wet hail and wet turbulence ice crystals dry hail and dry snow however these three elements give small reflections the radar does not detect clouds fog or wind droplets are too small or no precipitation at all clear air turbulence no precipitation

Question 218-26 : Which one of the following is an advantage of a secondary radar system when compared to a primary radar system ?

The required power of transmission from the ground equipment is reduced.

Secondary surveillance radar emits an interrogation pulse rather than a beam of energy you get back a response from the transponder rather than reflected energycalculating the time to response and return plus where the aerial was pointing during the process gives you the return on the displaythus the required power of transmission from the ground equipment is reduced

Question 218-27 : What information may be displayed on an atc radar screen connected only to a primary radar system ?

Aircraft position only.

Question 218-28 : In an airborne weather radar the areas of greatest turbulence are usually indicated on the screen by ?

Colour zones of red and magenta.

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Question 218-29 : Airborne weather radars are generally based on the use of ?

Primary radar in the shf band.

Question 218-30 : Mode a or c garbling may occur to ?

Two or more aircraft in the same direction from the interrogator with a difference in slant range of less than 17 nm.

Disadvantages of ssr mode ac code garbling of aircraft less than 17 nm apart measured in the vertical plane perpendicular to and from the antenna fruiting which results from reception of replies caused by interrogations from other radar stations

Question 218-31 : In a primary pulse radar you have ?

A directional aerial for both transmission and reception.

Question 218-32 : A tcas ii equipped ac will have mode s because ?

The datalink is required to co ordinate evasive manoeuvres.

Mode s selective is designed to allow automatic collision avoidancesense of ras coordinated between tcas equipped aircraft resolution advisories so tcas ii traffic alert and collision avoidance system automatically implies mode s transponderthe ra intensity is checked and revised if necessary every secondmore information can be found by using the link below

Question 218-33 : How does a mode s interrogator identify aircraft ?

A 24 bit identifier giving over 16 million combinations.

The provision of air traffic services ats using ssr mode s initially in a central area of european airspace will rely on a unique icao 24 bit aircraft address for selective interrogation of individual aircraft the 24 bit aircraft address is also an essential element of the airborne collision avoidance system acas ii in addition mode s surveillance requires the reporting of aircraft identification as stated in circular aic a 0104 concerning mode s airborne equipment requirementsthe aircraft address shall be one of 16 777 214 twenty four bit aircraft addresses allocated by icao to the state of registry or common mark registering authority and assigned as prescribed in the appendix to chapter 9 part i volume iii icao annex 10all mode s equipped aircraft engaged in international civil aviation are required to have an aircraft identification feature as prescribed in icao annex 10 volume iv chapter 2 2152

Question 218-34 : Which statement with respect to interrogation modes is correct ?

Mode s broadcast will transmit information to all mode s transponders.

Mode s is a secondary surveillance radar technique that permits selective interrogation of aircraft by means of a unique 24 bit aircraft address thus avoiding the risk of confusion or mis identification due to overlapping signals mode s has been standardised by icao for many years it employs ground based interrogators and airborne transponders and operates in the same radio frequencies 10301090 mhz as conventional ssr systems with which it is backwards compatiblemode s ground interrogators transmit a mode s all call at a steady rate similar to a conventional ssr any mode s transponder that is not locked out will reply to the interrogation transmitting its 24 bit aircraft address registration and its aircraft identification call sign

Question 218-35 : To improve the detection of precipitation area s in eg 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.

2620if the top of the cloud lies at or slightly above the level of flight and you decide to climb it will be better to tilt down your weather radar to maintain a good awareness of the situationif not you will not be able to see precipitations the risk is to see clear sky above the clouds and thus you will not be able to avoid large area of turbulences

Question 218-36 : Garbling is caused by ?

Aeroplanes in close proximity responding to the same interrogation.

Question 218-37 : Airborne weather radar has been primarily developed to detect ?

The kinds of precipitation which are usually accompanied by turbulence.

Question 218-38 : When an operator increases the range on a radar display in general ?

The prf becomes lower and the pulse length larger.

When an operator increases the range on a radar display larger pulses have smaller resolution and the prf pulse repetition frequency therefore needs to be slower to detect more distant pulses onofrio think about formulas max unambigious range c2xprf so prf has to decrease to increase the rangeandminimum range pl2 so pl has to increase to increase the range

Question 218-39 : The heaviest turbulence is likely to be encountered ?

Question 218-40 : 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.