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Question 212-1 : The pulse p2 of an interrogation in a/c mode has the function ? [ Preparation civilian ]
Of avoiding responses of aircraft located in the direction of the side lobes of the antenna of the interrogator.
Question 212-2 : A transponder receives a p2 pulse which is larger than that of the p1 and p3 ?
Transponder transmissions will be suppressed for a short time.
Question 212-3 : The integrity of a vor system is improved by ?
An automatic ground monitoring system.
Question 212-4 : The controller of a vdf ground station pass you the following message.'your true bearing is 256°, class alpha'..this is a ?
Qte accurate to a range within ± 2°.
.bravo nice and very interesting question from the easa, there's nothing more to say than that. 2559.qte the true bearing from the station..quj the true bearing to the station..qdr the magnetic bearing from the station..qdm the magnetic bearing to the station...vdf information is divided into the following classes according to icao annex 10. class a accurate to a range within ± 2°. class b accurate to a range within ± 5°. class c accurate to a range within ± 10°. class d accurate to less than class c.
Question 212-5 : Which of the following is the correct class and accuracy for a vdf direction finder ?
Class a ± 2°.
. 2604.they should take a break at the easa offices.....vdf information is divided into the following classes according to icao annex 10. class a accurate to a range within ± 2°. class b accurate to a range within ± 5°. class c accurate to a range within ± 10°. class d accurate to less than class c.
Question 212-6 : An aircraft is inbound to vor x on the 073° radial and experiences a drift of 12°l. a position report is required when crossing the 133° radial from vor y. if the aircraft is on track, the rmi indications at the reporting point would be ?
Heading 265°, x pointer 253°, y pointer 313°.
Question 212-7 : In the case where a dme station is subjected to more than 100 interrogations, which aircraft will no longer receive a response from the dme ?
Those who have the lowest transmission.
.a typical dme transponder can provide distance information to 100 aircraft at a time. above this limit the transponder avoids overload by limiting the gain of the receiver. replies to weaker more distant interrogations are ignored to lower the transponder load..dme can be used by 300 users at one time. the technical term of the dme station when its overloaded and cannot accept more than 100 aircraft is called 'station or beacon saturation'.
Question 212-8 : In the case where a dme station is subjected to more than 100 interrogations, which aircraft s will receive a dme response ?
Those who have the most powerful transmission.
.a typical dme transponder can provide distance information to 100 aircraft at a time. above this limit the transponder avoids overload by limiting the gain of the receiver. replies to weaker more distant interrogations are ignored to lower the transponder load..dme can be used by 300 users at one time. the technical term of the dme station when its overloaded and cannot accept more than 100 aircraft is called 'station or beacon saturation'.
Question 212-9 : What is the reason that a dme station can generally respond to a maximum of 100 aircraft ?
The number of reply pulse pairs per second that a dme transponder can transmit is limited to a certain maximum value.
Question 212-10 : Which entrance sectors should you use to enter a dme arc holding pattern ?
Sector 1 or 3.
.icao doc816 dme arc entry at the fix, the aircraft shall enter the holding pattern in accordance with either the sector 1 or sector 3 entry procedure...sector 2 is on the dme arc, which is why it is not in the allowed sectors to enter the holding pattern at the beginning of the dme arc...sector 1 procedure parallel entry.sector 2 procedure offset entry.sector 3 procedure direct entry.
Question 212-11 : A direction finding station working alone should give the following, as requested ?
Magnetic and true bearing to the station, magnetic and true heading for the station.
Ecqb04, november 2017.....a direction finding station working alone should give the following, as requested..1 true bearing of the aircraft..2 true heading to be steered by the aircraft, with no wind, to head for the station..3 magnetic bearing of the aircraft..4 magnetic heading to be steered by the aircraft with no wind to make for the station.
Question 212-12 : In vdf service the report 'qdr 235°, class c' means ?
The magnetic bearing from the station to the aircraft is 235° ± 10°.
Ecqb04, november 2017.... /com en/head explode.gif.they should take a break at the easa offices.....qte the true bearing from the station..quj the true bearing to the station..qdr the magnetic bearing from the station..qdm the magnetic bearing to the station...vdf information is divided into the following classes according to icao annex 10. class a accurate to a range within ± 2°. class b accurate to a range within ± 5°. class c accurate to a range within ± 10°. class d accurate to less than class c.
Question 212-13 : The sensitive area of an ils is the area vehicles or taxiing aircraft may not enter when ?
Category ii/iii ils operations are in progress.
The ils critical area is an area of defined dimensions about the localizer and glide path antennas where vehicles, including aircraft, are excluded during all ils operations...the critical area is protected because the presence of vehicles and/or aircraft inside its boundaries will cause unacceptable disturbance to the ils signal in space...the ils sensitive area is an area extending beyond the critical area where the parking and/or movement of vehicles, including aircraft, is controlled to prevent the possibility of unacceptable interference to the ils signal during ils operations...the sensitive area is protected against interference caused by large moving objects outside the critical area but still normally within the airfield boundary...critical areas must be protected to all times while ils sensitive areas, should be kept clear during cat ii or cat iii operations...airplane must stop taxing at the rwy cat ii or cat iii holding points.
Question 212-14 : You are flying along an airway which is 10 nm wide 5 nm either side of the centreline. the distance to the vor/dme you are using is 100 nm. if you are on the airway boundary, how many dots deviation will the vor needle show if one dot represents 2 degrees ?
1.5
Refer to figure..as seen in the figure, the aircraft is on the airway boundary which is 5 nm form the intended course. the cdi therefore will show a deflection to the right since the selected course will be directly inbound to the station.the distance that dme shows 100 nm. which should be the hypotenuse, but for the such distance, we can approximate that the distance from the airway is the same.to calculate the angle of deflection the aircraft has relative to the intended course we can use the following formulae.tangent correction angle = distance off intended track / distance to go = 5nm / 100nm = 0.05tan 1 0.05 = 2.86° = 3°if one dot represents 2° then 3° will be equal to 1 dot2° 3° = 3° x 1 dot / 2° = 1.5 dots1 60 solution.• track error angle = dist off track 60 ÷ dist along track.• tea = 5 nm 60 ÷ 100 nm.• tea = 3°if one dot represents 2° then 3° will be equal to 1.5 dots
Question 212-15 : If an aircraft flies along a vor radial it will follow a ?
Great circle track.
.a radial is a magnetic bearing extending from a vor station. radials move along the compass rose in all directions. radials follow the curvature of the earth, just like great circle tracks. as seen in the figure, great circle tracks run across the earth's surface following the curvature of the earth. the rhumb line is used for planning a flight on a 2d map.. 1462.the great circle track marks the shortest distance between 2 points, which is useful for navigation purposes...due to convergency usually the track changes along the great circle. the equator and all the meridians longitudes that run vertically across the earth. any circle that is not a great circle is called a small circle, also known as parallel of latitudes.
Question 212-16 : Locators are..1. high powered ndbs used for en route and airways navigation...2. low powered ndbs used for airfield or runway approach...3. beacons with a usually range of 10 to 250 nm...4. beacons with a usually range of 10 to 25 nm...the combination regrouping all the correct statements is ?
2 and 4.
Ndbs used for aviation are standardised by icao annex 10 which specifies that ndbs be operated on a frequency between 190 khz and 1750 khz. each ndb is identified by a one, two, or three letter morse code callsign...non directional beacons in are classified by power output low power rating is less than 50 watts medium from 50 w to 2,000 w and high at more than 2,000 w. 2..there are four types of non directional beacons in the aeronautical navigation service... . en route ndbs, used to mark airways. . . approach ndbs. . . localizer beacons. . . locator beacons. ...the last two types are used in conjunction with an instrument landing system ils...locator beacons are low powered beacons with a range between 10 to 25 nm maximum.
Question 212-17 : An aircraft is flying at fl 240. the dme reading, uncorrected for altitude, is 8 nm. what is the ground distance to the beacon ?
7.0 nm
Refer to figure...distance measuring equipment dme is a navigation beacon that can indicate the aircraft's position relative to the beacon. aircraft send out a signal which is sent back by the dme ground equipment. based on the delay of receiving the signal back, the aircraft can calculate the relative distance to the dme ground equipment...as seen in the figure, the aircraft is at an altitude of 24.000 feet. fl240...the slant range from the aircraft to the dme is 8 nm...by calculating the ground distance from the aircraft to the dme station, convert the following 24.000 feet into nautical miles...use the following table... . . 1 nm. 6080 ft.. . . . 24.000 ft.. . ... = 24.000 ft x1 nm / 6080 ft = 3,95 nm...using the abc formulae the following can be calculated..a² + b² = c²..knowing that..a = 3,95 nm..b =..c = 8 nm..rewriting the formulae gives the following..b² = c² a²..b² = 8 ² 3,95 ²..b² = 48,4..b = 48,4 = 6,95 nm = 7 nm.
Question 212-18 : What is the minimum level isa conditions that an aircraft, at a range of 111 nm, must fly in order to contact the tower on r/t for a vdf bearing from an airport sited 169 ft above msl ?
Fl60
A vdf facility is an abbreviation for very high frequency vhf direction finding...using this will give the pilot a determination of his current position...the formulae used to calculate the range of these radio waves is as follows..maximum theoretical range in nm = = 1.23 x h3 + 1.23 x h4..h3 = the height in feet of the transmitter above mean sea level msl...h4 = the height in feet of the receiver above mean sea level msl...rewriting the formulae gives the following..1.23 x h3 = range – 1.23 x h4..h3 = range 1.23 x h4 / 1.23 ²..knowing that..range = 111 nm..h4 = 169 ft..filling in the formulae gives the following..h3 = 111 nm 1.23 x 169 / 1.23 ² = 5966 ft = fl60
Question 212-19 : To determine the vor radial, the aircraft vor receiver… ?
Measures the phase difference between the reference phase and the variable phase signals.
A vhf omni directional range vor is used as a navigation beacon for aircraft. aircraft with a receiving unit will be able to determine their position relative to the vor beacon. the frequency of vor's appear in the very high frequency vhf range, from 108.00 to 117.95 mhz...a vor ground station sends a highly directional signal, by making use of a so called phased array antenna. together with this signal, the vor sends a 30 hz reference signal which is equal in all direction. the phase difference between the reference signal and the highly directional signal, is the bearing from the vor station relative to magnetic north...a vor receiver works by comparing the phase relationship between a reference signal and a variable signal.
Question 212-20 : Which of the following correctly describes the instrument landing system ils localiser radiation pattern ?
Two overlapping lobes on the same vhf carrier frequency
.radiation pattern are 90 hz and 150 hz signals. 2582.distribution of the frequencies seen in the approach direction. 2583.if the aircraft is exactly on the glidepath on the exact runway centreline , it receives a balance between modulations.
Question 212-21 : The middle marker of an instrument landing system ils facility is identified audibly and visually by a series of ?
Alternate dots and dashes and an amber light flashing
Refer to figure...there are three types of markers usually installed as part of a instrument landing system...outer marker..this marker normally indicates the final approach fix faf. it is located between 4 and 7 nm from the runway threshold on the same course as the localizer. when passing the outer marker the pilot receives an audio tone in continues series of 400 hz accompanied with a flashing blue light in a continuous series of 2 second dashes...middle marker..this marker normally indicates the cat i missed approach point and it is positioned between 0.5 and 0.8 nm from the runway threshold. when passing the middle marker the pilot receives an audio tone in continues series at 1300 hz accompanied with a flashing amber light in an alternating dots and dashes sequence...inner marker..this marker normally indicates the passing of the runway threshold. when passing the inner marker the pilot receives an audio tone in continues series of 3000 hz accompanied with a flashing white light in a dots sequence.
Question 212-22 : The mls frequencies and available channels are... ?
In the shf band, 300 khz frequency separation giving 200 available channels.
The microwave landing system mls was designed to replace ils with an advanced precision approach system that would overcome the disadvantages of ils and also provide greater flexibility to its users. however, there are few mls installations in use at present and they are likely to co exist with ils for a long time. mls is a precision approach and landing system that provides position information and various ground to air data. the position information is provided in a wide coverage sector and is determined by an azimuth angle measurement, an elevation measurement and a range measurement...the microwave landing system mls has the following features... . there are 200 channels available worldwide.. . . the azimuth coverage is at least ± 40° of the runway on course line qdm and glideslopes from.9° to 20° can be selected. the usable range is 20 30 nm from the mls site 20nm in the uk.. . . there is no problem with back course transmissions a secondary system is provided to give overshoot and departure guidance ± 20° of runway direction up to 15° in elevation to a range of 10 nm and a height of 10,000 ft.. . . it operates in the shf band, 5031 5090 mhz. this enables it to be sited in hilly areas without having to level the site. course deviation errors bending of the localiser and glidepath caused by aircraft, vehicles and buildings are no longer a problem because the mls scanning beam can be interrupted and therefore avoids the reflections
Question 212-23 : An aircraft is homing to a radio beacon whilst maintaining a relative bearing of zero. if the magnetic heading decreases, the aircraft is experiencing ?
Right drift
Refer to figure...when an aircraft is homing to, for example, to a vor station, it means that the aircraft flies the most direct heading to reach the station. important to know is that heading does not take into account the wind. the lateral displacement an aircraft is experiencing due to the wind is called drift...as seen in the figure the aircraft is homing to the vor station on heading 360. however this is the heading needed to fly directly to the station without taking into account the experienced drift. the direction of drift depends on the direction of the wind. to correct for the drift angle, a wind correction angle is needed. the wind correction is always against the wind, so left wind, left wind correction angle. right wind, right wind correction angle...as general rule..when the aircraft experiences right drift, meaning a wind from the left, the track will be heading + drift angle..when the aircraft experiences left drift, meaning a wind from the right, the track will be heading – drift angle..if heading 360 is selected but the track indicates heading 010, the aircraft will not reach the station. when the aircraft magnetic heading decreases, meaning the heading will become less than 360, the airplane is correcting for right drift, as seen as the red dotted line in the figure.
Question 212-24 : Which one of the following disturbances is most likely to cause the greatest inaccuracy in adf bearings ?
Local thunderstorm activity
Thunderstorms can have very powerful discharges of static electricity across the electromagnetic spectrum including in low frequency lf and medium frequency mf. these discharges cause the most severe errors in ndb/adf...a static discharge in a cumulonimbus cloud cb can be heard as a loud crackle on the audio and the needle will move rapidly to the source of the cb. if there are several active thunderstorms in the area the needle might point to them for a longer period.
Question 212-25 : Of what use, if any, is a military tacan station to civil aviation ?
It can provide dme range.
Learning objective 062.02.04.01.08 state that military uhf tactical air navigation aid tacan stations may be used for dme information..tacans are military radio aids that can be used by military aircraft with the correct receiver fitted. they can give distance and radial information, similar to a vor/dme installation can. civilian aircraft are limited, and can use the distance function the same as using a dme, but cannot receive the radial information.
Question 212-26 : Which of the following is an ils localiser frequency ?
109.15 mhz
The ils localizer frequency appear in the very high frequency vhf , ranging between 108.10 and 111.95 mhz. only the frequencies that start with the odd decimals are used specifically as localizer frequencies. for example 108.10, 108.15, 108.30, 108.35 etc...the only correct answer for this question can be the frequency between 108.10 and 111.95 mhz which has an odd decimal number, so in this case 109.15 mhz... continues on next page... . . frequency name. frequency. application. . . very low frequency vlf. 3 30 khz. nil. . . low frequency lf. 30 300 khz. ndb/adf. . . medium frequency mf. 300 3000 khz. ndb/adf, long range communications. . . high frequency hf. 3 30 mhz. long range communications. . . very high frequency vhf. 30 300 mhz. short range communication, vdf, vor, ils localizer, marker beacons. . . ultra high frequency uhf. 300 3000 mhz. ils glide path, dme, ssr, satelite communications, gnss, long range radars. . . super high frequency shf. 3 30 ghz. radalt, awr, mls, short range radars. . . extremely high frequency ehf. 30 300 ghz. nil
Question 212-27 : An ndb transmits a signal pattern in the horizontal plane which is ?
Omnidirectional
Non directional beacon ndb..the ndb is a ground based transmitter operating in the mf or lf band widths and situated in a ground station that broadcasts signals in all directions omnidirectional , which are received by the adf or automatic direction finder, a standard instrument onboard aircraft.
Question 212-28 : A vor and an ndb are located in the same position. both the vor and the adf readings are displayed on the rmi. the aircraft is tracking away from the beacons along the 090 radial. the magnetic variation is changing rapidly. which of the following is correct ?
The direction of the adf pointer will change, the direction of the vor pointer will not change.
There are significant differences in adf and vor systems... an automatic direction finding adf system uses a groundbased non directional beacon ndb that broadcasts an omnidirectional am signal that can be picked up by the aircraft's adf system. this way the ndb system can be located on the ground. adf is a short/medium range navigation system operating between 190 and 1750 khz.. a vhf omnidrectional range vor system works on the principle of phase difference in the two radio signals transmitted from the vor station. one signal is omnidirectional while the other signal is a 360degrees variable. radials. vor operates in the range of 108 and 117.95 mhz...the big difference between adf and vor systems is the magnetic variation. when ndb/adf is in use, the magnetic variation will change at the aircraft instruments. while using vor systems the magnetic variation will always happen at the station itself...when flying away from the station, the radial at which the aircraft is flying will always be the same indication since it's not changing at the aircraft. the needle of the adf will show a variation magnetic variation as the aircraft moves away from the station.
Question 212-29 : Which of the following is correct regarding false beams on a glide path ?
False beams will only be found above the correct glide path.
Refer to figure...the glidepath works similar to the localizer, except the glidepath operates in the ultra high frequency uhf instead of the very high frequency vhf band. as seen in the figure, there are 2 lobes on the glidepath. one lobe at 90 hz which indicates that the aircraft is above the glidepath. and one lobe at 150 hz which indicates that the aircraft is below the glidepath. the centre is typically set to a 3° glidepath...despite the accuracy of the system, there can be some sidelobes created. these sidelobes are not as powerful as the main ones but can provide multiple false glideslopes above the main lobe. false glideslopes will never be encountered when approaching the glidepath from below. an indication of a false glidepath could be seen in the rate of descent. if the rate of descent required is higher than stated in the charts, for example 1500 fpm instead of 500 fpm, the aircraft will be on a false glidepath. the false glidepath is usually about twice the normal angle and the weaker side lobes may indicate up to 4 times the glide angle.
Question 212-30 : Which one of the following correctly lists the major ground based components of a microwave landing system mls ?
Separate azimuth and elevation transmitters, dme facility
The microwave landing system mls is a precision radio guidance system, that is used to guide the aircraft towards the runway. the principle works the same as an instrument landing system ils , it gives horizontal and vertical guidance to land in all weather conditions...the system consists of several different parts... approach azimuth. back azimuth. elevation guidance. range guidance dmep. data communications
Question 212-31 : One of uses of the vdf service is providing aircraft with ?
Homing.
The vhf direction finder vdf is a means of providing a pilot with the direction to fly towards a ground station, a bearing. the bearing can be used to ‘home’ towards the ground station or it can be used to identify the exact position of the aircraft by multiple bearings from other vdf facilities...a pilot may request a vdf bearing using the appropriate phrase of q code...the following q codes can be used..qdm = magnetic bearing to the station..qdr = magnetic bearing from the station..quj = true bearing to the station..qte = true bearing from the station
Question 212-32 : To provide a pilot with the position of the aircraft in the absence of radar, atc must have at its disposal at least… ?
Two vdfs at different locations, able to take bearings simultaneously on the transmitted frequency.
Vdf vhf direction finding is a method of measuring the direction from which a vhf signal came. it has been used for many decades now by ground stations, and is particularly useful as the transmitting aircraft only needs a standard vhf radio to ask for a vdf bearing from a suitably equipped atsu. this can give them....qdm magnetic bearing from the aircraft to the station...qdr magnetic bearing from the station to the aircraft...quj true bearing from the aircraft to the station...qte true bearing from the station to the aircraft.....with 2 suitable bearings from different ground stations, there is enough information to calculate a location of an aircraft, whether that is the pilot drawing on a chart and finding the location, or the controllers on the ground using their system. more bearings provide a more accurate location, and the best bearings are where the lines cross at close to 90º. this means that the two vdf ground stations are required, that are not too close together...these days, a computer system with access to multiple vdf aerials can perform a process called auto triangulation to find the exact location that a particular transmission was broadcast from. this is most notably used by distress and diversion 121.5 mhz.
Question 212-33 : Allocated frequencies for ndb are ?
190 khz to 1750 khz.
An ndb or non directional beacon is a ground based, low frequency radio transmitter used as an instrument approach for airports and offshore platforms. the ndb transmits an omni directional signal that is received by the adf or automatic direction finder, a standard instrument onboard aircraft. the pilot uses the adf to determine the direction to the ndb relative to the aircraft...to navigate using the adf, the pilot enters the frequency of the ndb and the compass card or arrow on the adf will indicate the heading to the station. the signal is transmitted on an uninterrupted 24/7 basis.an audible morse code call sign of one or more letters or numbers is used to identify the ndb being received. ndb’s used for aviation are standardized by icao, the international civil aviation organization, annex 10 which specifies that ndb be operated on a frequency between 190 to 1800 khz...the main components of an ndb ground station are the beacon transmitter, antenna tuning unit and antenna.typically ndbs have output power from 25 to 125 watts for reception up to approx. 100 nm.higher power systems from 500 to 1000 watts are used for longer range applications. range depends on a number of factors such as output power, antenna, ground conductivity, frequency, site conditions, latitude, and the condition of the adf receiver.
Question 212-34 : Locators are ?
Lf/mf ndbs used as an aid for final approach.
Locator beacons are low powered ndbs used for terminal procedures and approaches, with useful ranges of between 10 and 25 nm. ndbs are non directional beacons that transmit a simple carrier wave with a modulation to overlay the morse code identifier. the adf automatic direction finder is the equipment in the cockpit which points a needle directly towards the ndb in question, by finding out which direction the radio wave arrived from...ndbs operate between 190 and 1750 khz, which spans both the lf low frequency, 30 300 khz and mf medium frequency, 300 3000 khz frequency bands.
Question 212-35 : According to icao annex 10 a locator has a range of ?
10 to 25 nm
Refer to figure...the outer marker, which normally identifies the final approach fix faf , is often combined with a non directional beacon ndb which together creates the locator outer marker lom. the lom is used as a navigational aid for the ils, so that aircraft will be alerted when overflying it, and offer the possibility to fly to it directly...as seen in the figure, icao annex 10 states the following
Question 212-36 : Tvor is a.. ?
Vor with a limited range used in the terminal area.
Vor applications..vors are used for en route navigation, usually to define airway centrelines. the overall required accuracy of the displayed information is ± 5°. when european airways were first plotted out a lower accuracy of ± 7.5° was assumed. to keep an aircraft within the confines of an airway 10nm, maximum distance between the beacons was calculated to be 80nm...vor can be classified as follow..a terminal vor tvor is a low power beacon used as part of an airfield approach. tvors share the lower frequencies with ils...a broadcast vor is usually a terminal aid with a voice broadcast giving out the airfield weather atis superimposed on the carrier wave...a test vor vot is a very low power beacon sited at airfields. it puts out a constant phase difference of zero in all directions. this allows aircraft to test the accuracy of their equipment on the ground. the vor test function is selected with a course of 000° set. the course deviation indicator should centre with from indicated, the rmi should indicate 180° qdm. the beacon ident for a test vor is a series of dots...pay attention do not confuse a tvor with a test vor ..question 623419..max range at which you will receive a signal/indication will depend on trasmitter power, altitude, receiver sensitivity, atmospheric conditions and various other intangible factors...the max theoretical range in nautical miles was always worked out thus ..r = 1.23 h3 + h4..where..h3 = altitude/ height of the reciver in ft..h4 = elevation of the ground facility in ft..111 nm = 1.23 ft + 169 ft ..111 nm = 1.23 ft + 13 ft .. ft + 13 = 111 ÷ 1.23.. ft + 13 = 90.4.. ft = 90.4 – 13.. ft = 77.24.. = 77.242 .. = 5967 = fl60
Question 212-37 : On an rmi the front end of a vor pointer indicates the ?
Radial plus 180°.
Refer to figure...heading. the direction in which the longitudinal axis of an aircraft is pointed, usually expressed in degrees from north true, magnetic, compass or grid...track. the projection on the earth's surface of the path of an aircraft, the direction of which path at any point is usually expressed in degrees from north true, magnetic or grid...radial. a magnetic bearing extending from a vor/vortac/tacan...bearing. the horizontal direction to or from any point, usually measured clockwise from true north, magnetic north, or some other reference point through 360 degrees...heading vs. radial..the radial gives the relative position of an aircraft to e.g. a vor...there is no mathematical relation between the radial and the heading or track of an aircraft, i.e. one cannot be derived from the other...remember the vor needle indicates where the aircraft is radially with respect to the staion the arrow head indicates the qdm for the vor bearing to the vor station , while the ther end shows the qdr, or vor radial on which the aircraft is positioned at that moment.
Question 212-38 : Which statement about the interrogation by the dme interrogator is correct ?
The interrogation does not start before pulse pairs of the tuned dme station are received.
Tuning the dme interrogator in the aircraft starts the transmission of pulse pairs in search mode. no information is received by the interrogator at this point. when the pulse pairs are received by the transponder at the ground station, it adjusts the frequency by a pre determined + or 63 mhz, which are transmitted back to and received by the interrogator. it is only now that we have a closed loop between the interrogator and the transponder. think about it logically, you cannot interrogate something unless you have first established communications with that something...therefore, simply transmitting in search mode cannot be considered to be an interrogation, the loop must be closed first to establish there is a transponder present to interrogate.
Question 212-39 : An aeroplane is on approach with nav 1 tuned to the ils frequency and nav 2 tuned to the vor frequency which also provides an approach to the same runway. when the cdi of nav 1 is at exactly full scale deflection, the nav 2 cdi will show approximately... ?
Quarter scale deflection.
Refer to figure...vors and ilss often use the same displays in the cockpit, with the lateral display of the cdi course deviation indicator useful for displaying vor or localiser deviation, and the vertical display showing glide path deviation. they do not, however, have the same level of accuracy, as a localiser has to be much more accurate than a vor...therefore, on a standard 5 dot cdi, vors have a deviation indicated by 2 degrees per dot, so full scale deflection is 10º deviation from the selected bearing...ils localisers loc on the other hand have just 0.5 degrees per dot deviation, so full scale deflection is 2.5º deviation from the localiser centreline...therefore, in this scenario, where we are on exactly full scale loc deflection, we are 2.5º off the correct inbound course, which is a quarter of the scale deflection on the vor display.
Question 212-40 : Mls is primarily being installed at airports where ?
Ils encounters difficulties because of surrounding buildings and/or the terrain or interference from local music stations.
The microwave landing system mls was designed to replace ils with an advanced precision approach system that would overcome the disadvantages of ils and also provide greater flexibility to its users...however, there are few mls installations in use at present and they are likely to co exist with ils for a long time.mls is a precision approach and landing system that provides position information and various ground to air data.the position information is provided in a wide coverage sector and is determined by an azimuth angle measurement, an elevation measurement and a range measurement...mls has the ability to interrupt the transmitted signal to avoid reflection by stationary objects such as obstructions in the appropach path which makes the system less sensitive to geographic location and obstacles.this and the relatively low cost of the system are its main advantages...subsidiary advantages are the ability of mls equipped aircraft to fly approach paths other than straight in and the single frequency used avoiding the requirement for frequency pairing.
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