Ndb is a ground equipment, and adf is an airborne equipment.
Ndbs are non directional beacons that transmit a simple carrier wave with a modulation to overlay the morse code identifier. they are a ground station consisting of just one aerial for transmission...the adf automatic direction finder is the equipment in the cockpit which measures the direction from which the ndb carrier wave signal came, and points a needle directly towards the ndb in question on one of the pilot's instruments...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 213-2 : The adf indication in the cockpit is a ?
Relative bearing on a fixed card indicator
Refer to figure.. the adf indication on a fixed card inside the cockpit is a rbi relative bearing indicator.. the rbi is measured in clockwise direction from the nose of the aircraft.
Question 213-3 : Night effect in an adf may cause ?
Fluctuating indications of the needle on the rmi.
By day the d region absorbs signals in the lf and mf bands. at night the d region disappears allowing sky wave contamination of the surface wave being used...the reason why this arises is because the phase interference of the sky wave with the surface wave because of the different paths and the induction of currents in the horizontal elements of the loop aerial...the effect is manifest by fading of the audio signal and the rmi needle fluctuating is worst around dawn and dusk, when the ionosphere is in transition.
Question 213-4 : Which statement is correct with respect to the different types of vor ?
A tvor has a limited range.
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.
Question 213-5 : On an ils approach, when flying overhead the middle marker the colour of the flashing light will be ?
Amber.
Refer to figure...there are three types of markers installed as part of a instrument landing system ils..outer marker om..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 mm..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 im..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 213-6 : On an ils approach, when flying overhead the inner marker if available the colour of the flashing light will be ?
White.
Refer to figure...there are three types of markers installed as part of a instrument landing system ils..outer marker om..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 mm..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 im..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 213-7 : On final on an ils approach, you are flying overhead the outer marker. you can expect to be at ?
4 nm from the threshold.
There are three types of markers installed as part of a instrument landing system ils..outer marker om..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 mm..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 im..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 213-8 : The uhf band is the assigned frequency band of the ?
Ils glide path transmitter.
Refer to figure...as seen in the figure ultra high frequency uhf is, along with several others, assigned to the ils glide path transmitter.
Question 213-9 : Ils transmitters use the ?
Uhf and vhf bands.
Ils main component are..localizer...the localizer loc ground antenna array is located on the extended centerline of the instrument runway of an airport, remote enough from the opposite approach end of the runway to prevent it from being a collision hazard...this unit radiates a field pattern, which develops a course down the centerline of the runway toward the middle markers mms and outer markers oms , and a similar course along the runway centerline in the opposite direction...these are called the front and back courses, respectively...the localizer provides course guidance, transmitted at 108.1 to 111.95 mhz odd tenths only , throughout the descent path to the runway threshold from a distance of 18 nm from the antenna to an altitude of 4,500 feet above the elevation of the antenna site...the localizer course is very narrow, normally 5°. this results in high needle sensitivity...with this course width, a full scale deflection shows when the aircraft is 2.5° to either side of the centerline...this sensitivity permits accurate orientation to the landing runway...with no more than one quarter scale deflection maintained, the aircraft will be aligned with the runway...glide slope...glide slope gs describes the systems that generate, receive, and indicate the ground facility radiation pattern...the glide path is the straight, sloped line the aircraft should fly in its descent from where the glide slope intersects the altitude used for approaching the faf, to the runway touchdown zone...the glide slope equipment is housed in a building approximately 750 to 1,250 feet down the runway from the approach end of the runway, and between 400 and 600 feet to one side of the centerline...the course projected by the glide slope equipment is essentially the same as would be generated by a localizer operating on its side...the glide slope projection angle is normally adjusted to 2.5° to 3.5° above horizontal, so it intersects the mm at about 200 feet and the om at about 1,400 feet above the runway elevation...at locations where standard minimum obstruction clearance cannot be obtained with the normal maximum glide slope angle, the glide slope equipment is displaced farther from the approach end of the runway if the length of the runway permits or, the glideslope angle may be increased up to 4°...marker beacons..all markers operate on 75 mhz vhf thus no frequency selections are necessary for the pilot and radiate a fan shaped field pattern giving to the pilot an indication of range from the threshold...the purpose of the markers is to provide range information while on the approach...they transmit an almost vertical beam. almost all installations are equipped with an outer marker and a middle marker...category 2 or 3 ils may be equipped with an inner marker as well...audio and visual signals in the cockpit will indicate when the aircraft is passing overhead...in many installations, marker beacons are being replaced or supplemented by the use of a dme associated with the ils.
Question 213-10 : The localiser transmitters operate in a frequency band between ?
108 mhz and 111.975 mhz.
Refer to figure...the ils localizer appears in the very high frequency vhf , ranging between 108.10 and 111.975 mh
Question 213-11 : 108.35 mhz can only be ?
An ils frequency.
The ils localizer frequency appear in the very high frequency vhf , ranging between 108.10 and 111.95 mhz...the vor appears in the vhf band, typically between 108.00 and 117.95 mhz.... the range between 108.00 and 111.95 mhz is split between the ils and terminal vors, so that an even number in the first decimal place is a vor and an odd number is an ils. therefore, 108.35 mhz is an ils frequency.
Question 213-12 : Which statement about adfs is correct ?
Adfs can receive and take bearings on any broadcasting station transmitting within the frequency band 190 – 1750 khz.
Refer to figure...as seen in the figure, the adf operates in both the low frequency lf and medium frequency mf band. specifically the adf is able to receive bearings between 190 and 1750 khz.
Question 213-13 : 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.
The response function of a dme transponder involves a continuous process that operates at a transmission rate of 2 700 pairs of pulses per second ppps. once the transponder starts receiving pulses at this rate, it reaches a state of saturation, leading to an automatic reduction in its receiver gain. this adjustment has the consequence of filtering out transmissions from aircraft whose interrogation pulses are relatively weaker...in practical terms, this translates to approximately 100 aircraft concurrently utilizing the dme system...the fortunate group of 100 consists of those aircraft emitting the most potent interrogation signals, rather than necessarily being the closest ones. when the ground based dme station undergoes saturation, it exclusively acknowledges the 100 most robust signals.
Question 213-14 : If the number of pulse pairs received by the dme transponder exceeds the maximum number possible, which aircraft will always be denied a dme range first ?
The aircraft from which the weakest pulse pairs are received.
Distance measuring equipment dme is a type of secondary radar system that provides slant range using the pulse technique. the aircraft’s interrogator transmits a stream of pseudo random omni directional pulse pairs on the carrier frequency of the ground transponder. the ground transponder then receives these, waits for 50 microseconds, and repeats those pulse pairs outwards at a frequency 63 mhz above the interrogation frequency.the airborne system identifies its own unique stream of pulse pairs and measures the time of arrival electronically, between the start of the interrogation and the reception of the ground transponder's replies. given the time delay minus known times such as the 50 microseconds , the distance between the aircraft and the dme ground station can be quite precisely calculated.as there is only one interrogation frequency and one reply frequency for each dme ground station, they can only service a certain number of pulses per second, and it ends up meaning that the dme becomes saturated with around 100 aircraft using it, and it will then prioritise the pulses with the strongest signal. the aircraft that are closer to the ground station, and the ones with the stronger transmitting power will therefore be higher priority to be serviced by the dme ground station.
Question 213-15 : If during an ils approach after having been established the pilot deviates by more than half scale deflection on the localizer ?
An immediate missed approach should be executed because obstacle clearance may no longer be guaranteed.
The instrument landing system ils is a system that provides the guidance of an aircraft towards the final approach. the system provides the aircraft with specific horizontal localizer and vertical glideslope guidance. with determining the limits of these guidances there will be a specific area determined which is clear of obstacles...an aircraft that has turned onto the inbound heading and is within 2,5 degrees of the localizer course which means half a scale of deflection on the ils instrument in the cockpit is established on the final approach course...half a scale of deflection are the boundaries of the ils and once going further than half a scale deflection, there might not be enough obstacle clearance and a go around should be initiated.
Question 213-16 : Fm broadcast stations transmitting just below 108 mhz are ?
Likely to cause interference to ils receivers not equipped with an immunity filter.
The instrument landing system ils localizer operates between 108 and 111.975 mhz...fm broadcasting is a method of radio broadcasting using frequency modulation fm.fm broadcasting uses the same frequency range as the ils, the very high frequency vhf range...the receiving unit of the ils on the aircraft will receive the radio waves that the ils is sending out. apart from the correct radiowaves, the receiving unit can also receive the broadcasted fm radio signals, which will interfere the ils indication and might give false data. adding onboard electro magnetic interference emi filters, immunity filters or special layout techniques can help in bypassing the interference received from the fm broadcasts.
Question 213-17 : The definition of the term qdr is… ?
The magnetic bearing from the station
Refer to figure...as seen in the figure there is a system of abbreviations that indicates what kind of bearing is described...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 213-18 : Reflections from large objects within the ils coverage area may cause ?
Multi path interference.
An instrument landing system ils consists of a localizer and a glide path. this system needs to be installed in possibly uneven terrain. uneven terrain might interfere with the ils...multipath interference to ils depends on the type of antenna used and any large reflecting objects in the area, like mountains. moving objects can degrade the directional signals that the interference on the system will be too high to be tolerated.
Question 213-19 : The accuracy the pilot has to fly the required bearing in order to be considered established during an adf approach according to icao doc 8168 as within plus or minus ?
5°
A non directional beacon ndb 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...a non precision approach is an instrument approach and landing which utilises lateral guidance but does not utilise vertical guidance. icao annex 6...non precision approaches which are pilot interpreted make use of ground beacons and aircraft equipment such as vhf omnidirectional radio range vor , non directional beacon and the llz element of an ils system, often in combination with distance measuring equipment dme for range...lateral guidance is provided by a display of either bearing to/from a radio beacon on the approach track or at the airfield or, in the case of an llz only approach, by display of the relative position of the llz track on the aircraft ils instruments and vertical guidance is based on the range from the airfield as indicated by a dme at the airfield or on track or by timing based upon passage overhead radio beacons on the track described by the designated procedure...remember in terms of lateral errors permitted, flying an ndb npa you must maintain a qdm/qdr that is ± 5° of the designated approach
Question 213-20 : With respect to the monitoring system of a vor which statement is correct ?
Failure of the vor station to stay within the required limits can cause the removal of identification and navigation components from the carrier or radiation to cease.
All vor beacons are monitored by an automatic site monitor. the monitor will warn the control point and remove either the identification and the navigational signals or switch off the beacon in the event of the following.. bearing information change exceeding 1°. a reduction of more than 15% in signal strength. a failure of the monitor
Question 213-21 : Which frequency can be used by a terminal vor ?
108.20 mhz.
Refer to figure...as seen in the table the vor vhf omnidirectional range uses the very high frequency vhf band to transmit it's electromagnetic waves. terminal vor uses specific frequencies. vor uses even decimals and even decimals plus 0.05 mhz. for example 108.0, 108.005, 108.20, 108.25, 108.40, 108.45 etc.
Question 213-22 : A pilot is tracking inbound to a vor on a designated radial using the hsi. the vor ground station is located in an area with varying terrain and man made obstructions. the pilot notices that the cdi is fluctuating slightly, even though he/she is constantly and accurately tracking inbound to the ?
Scalloping
Site error is caused by uneven terrain, for example, hills, trees, buildings and long grass near the transmitter. although the propagation has left the vor with ±1° accuracy, propagation error still exists. propagation error is caused by the terrain and distance. at a certain range from the vor so called ‘bends’ or ‘scalloping’ can occur.vor scalloping is described as an imperfection or deviation in the received vor signal. scalloping causes the signal to bend as a result of reflections from buildings and terrain. scalloping also causes the course deviation indicator cdi to slowly or rapidly shift from side to side. scalloping has a negative effect on the accuracy of the navigation aids used.
Question 213-23 : The magnetic variation to convert the rmi bearings of ndbs and vors to true bearings will occur at the.. ?
Aircraft position for ndbs and at the beacon position for vors.
An important fact is that the vor radial information is determined at the vor station – therefore, if you need to convert between true and magnetic when dealing with vor bearings, you have to apply the value of magnetic variation valid at the place of the vor station.for ndb/adf bearings is the opposite the bearings are taken at the aircraft, therefore the magnetic variation applicable at the aircraft’s position is to be used
Question 213-24 : The frequency range of a vor receiver is ?
108 to 117.95 mhz
Refer to figure...as seen in the table the vor vhf omnidirectional range uses the very high frequency vhf band to transmit it's electromagnetic waves. vor beacons operate between 108.0 and 117.95 mhz.
Question 213-25 : Which of the following is the icao allocated frequency band for aeronautical ndbs ?
190 khz to 1750 khz
Refer to figure...as seen in the figure, the non directional beacon ndb operates in both the low frequency lf and medium frequency mf band. the ndb is able to receive bearings between 190 and 1750 khz.
Question 213-26 : Errors caused by the effect of coastal refraction on bearings at lower altitudes are maximum when the ndb is.. ?
Inland and the bearing crosses the coast at an acute angle.
The effect of coastal refraction can be minimized by flying higher...naturally when flying lower, the coastal refraction experienced will be worse...radio waves speed up over water, causing the wave front to bend away from its normal path and pull it towards the coast...coastal refraction is negligible when the aircraft is perpendicular 90° to the coast. the coastal refraction increases as the angle to which the aircraft cuts the shoreline decreases.
Question 213-27 : The dme distance measuring equipment operates in which frequency range ?
960 to 1215 mhz
Distance measuring equipment dme is defined as a combination of ground and airborne equipment which gives a continuous slant range distance from station readout by measuring time lapse of a signal transmitted by the aircraft to the station and responded back...dmes can also provide groundspeed and time to station readouts by differentiation...the dme will measure the distance in a straight line to the ground beacon the slant range , not the distance from a point on the ground vertically below the aircraft ground range. the difference is generally insignificant, except that when directly over a beacon when the distance shown will be height above the beacon...dme operates in the ultra high frequency uhf band and the 252 available channels are contained between 960 and 1215 mhz...it utilises a double pulse in both the interrogator and the transponder. all pulses are the same duration, that is, 3.5 micro seconds...discrimination between channels is accomplished by both frequency separation and pulse spacing...channels are numbered from 1 to 126 and each channel number is further divided into two channels designated ‘x’ and ‘y’...each numbered pair of channels is separated from the adjoining pair by 1 mhz. the ‘x’ channels are separated from the ‘y’ channels by varying the pulse separation time. the pulse separation spacing is the same for all ‘x’ channels, being 12 micro seconds for both the interrogator and the transponder...in the case of ‘y’ channels the pulse spacing is 36 micro seconds for the interrogator and 30 micro seconds for the transponder.
Question 213-28 : The frequency of the amplitude modulation and the colour of an ils outer marker om light is.. ?
400 hz and blue.
Outer marker om..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.
Question 213-29 : A dvor is less sensitive to site errors than a cvor because.. ?
The variable phase is frequency modulated rather than amplitude modulated.
Refer to figure.. vor ground stations transmit two separate signals, one is the reference signal, and the other is the variphase signal. the principle of operation of conventional vors cvors is that the reference signal is omnidirectional, so all positions receive the signal equally, but the variphase signal is transmitted by a spinning antenna, so it appears at each position radial at a different time in comparison to the reference signal. radio waves like this are not pulses though, they are continuous sine waves, therefore the difference we measure between the reference signal and the variphase signal is a phase difference, simply put, a timing difference, that can be measured to give the receiver their vor radial. the two signals are easy to compare against each other as they are the same frequency, but differently modulated so both can be picked up separately.in a cvor, the reference signal is fm frequency modulated and the variphase signal is am amplitude modulated.in a dvor, the reference signal is am, and the variphase signal is fm.dvor stands for doppler vor, and they are much bigger ground units with larger antennas , that use the opposite modulation to cvors, and their variphase signal comes from a single omnidirectional signal that is sent to a ring of different antennas see annex above one at a time, travelling round the circle, to create a virtual travelling antenna. this causes a doppler frequency shift of the signal, depending on the aircraft's vor radial. this can then be compared to the am reference signal in the same airborne receivers as for cvors to provide a radial, which is then used in standard vor displays. because the aircraft does not know which type it is using, dvors are slightly modified signal spins the opposite direction , so it acts the same as a cvor to a receiver.dvors are more common these days, as they are less prone to site errors due to multipath errors and interference. this is because their variphase signal is fm, which is much less prone to interference from other signals that bounce off surfaces nearby to the line of sight signal. amplitude modulation, on the other hand, has some strong interference effects from interference and reflected radio waves. as the variphase signal is the one which counts in this respect for reasons well above the syllabus , dvors are less prone to site and multipath errors.note in the past a question like this has been seen that mention larger, more powerful signals as the reason dvors are better. this is not true, as bigger antennas will help a little bit, but that is not the primary reason they are less prone to errors than cvors.
Question 213-30 : The ils receiver of an aircraft on approach and flying to the right of the runway centreline will receive.. ?
More of the 150 hz localiser signal than the 90 hz localiser signal.
Refer to figure...as seen in the figure, the localizer as part of the ils covers the lateral area in front of the runway. which ever lobe the aircraft is closest to, will receive a greater strength...if the aircraft is to the left of the runway centre line, it will receive a greater strength from the 90 hz lobe than from the 150 hz lobe...if the aircraft is to the right of the runway centreline line, it will receive a greater strength from the 150 hz lobe than from the 90 hz lobe. this is the principle of how the localizer works.
Question 213-31 : Regarding ils operations, which of the following circumstances will trigger warning flags for the llz and the gp..1. the measured ddm is zero..2. the absence of the 90 hz and 150 hz modulation simultaneously..3. the cloud base as reported by the atis is below landing minima..4. the modulation depth ?
2 and 4
Warning flags on an ils will be triggered because of the absence of the lobes. only when in reach of the localizer and glideslope, the lobes of 90 hz and 150 hz will be correctly read.... . this will not trigger a warning, this will simply indicate that the aircraft is on the ideal 3° glideslope and perfectly on the runway centre line.. . . warning flags will be triggered when either the glideslope or the localizer is out of the reach and there might be a risk of false lobes.. . . the cloud base does not have influence on the correct operation of the ils. the lobes work regardless of the weather.. . . warning flags will be triggered when the modulation depth of both the localizer and glideslope are reduced to zero, meaning that there’s no correct indication available.
Question 213-32 : An aircraft tracking to intercept the instrument landing system ils localiser inbound on the approach side, outside the published ils coverage angle.. ?
May receive false course indications.
The localizer coverage area extends to a maximum angle of 35° of the localizer centreline. outside the coverage area the aircraft will receive a faulty localizer signal. these signals are called false courses and may lead to trouble because the aircraft will not receive the proper guidance towards the runway...false courses are a byproduct of the ils signals and are created at all angles outside the coverage area. during maintenance of the ils, false courses might also be generated inside the coverage area, which is why the ils will be unserviceable out of use when maintenance is being performed.
Question 213-33 : An aircraft at fl300, in isa conditions and with a ground speed of 300 kt, is about pass overhead a dme station at msl. the dme receiver is capable of determining ground speed. one minute before the overhead, dme speed and distance indications are respectively.. ?
Less than 300 kt and 7 nm.
Refer to figure...important to know with this question is that the groundspeed is only accurate when the aircraft is flying directly towards or away from the dme station. meaning that the indication given by the dme will usually be less than what the aircraft is actually flying.....the dme on board the aircraft will indicate the purple slant range..the aircraft is 1 minute from the dme, meaning that the ground distance towards the station will be... . . 300 nm. 60 min. . . . 1 min. . ........ = 1min x 300 nm / 60 min = 5 nm...knowing that the ground distance to the station is 5 nm, the slant range dme indication can be calculated by using the following..fl300 = 30.000 ft = 4.9 nm = 5 nm.....the slant range can be used by using the following the pythagoras theorem..slant range = ground distance ²+ aircraft height 2..slant range = 5 nm ²+ 5 nm ² = 7 nm.
Question 213-34 : An ils glide path provides azimuth coverage... i each side of the localiser centreline to a distance of... ii nm from the threshold. ?
I 8° ii 10
Refer to figure...localiser coverage... . from the center of the localiser aerial to 25 nm within ±10° of the approach bearing.. . . from the center of the localiser aerial out to a distance of 17 nm within ±35° of the approach bearing.. . . in some regions, where a steep angle glidepath is authorised, coverage is provided from the center of the localiser aerial to 18 nm ±10°, and 10 nm ±35°.. . . upper limit of the localizer signal vertical coverage is a minimum of 7° above the localizer horizontal plane.. . . the protection range and height of ils is 25 nm / 6 250 ft.. ...note 1 any attempt to use the localiser outside the areas listed above may lead to false/reverse sense indications. use outside designated coverage areas is therefore not permitted...glidepath coverage... . vertical coverage from 0.45 to 1.75 above the horizontal through the ils threshold = glide path angle. this equates to 1.35° to 5.25° above the threshold horizontal for a nominal 3° glide path.. . . horizontal coverage extending in azimuth 8° either side of the extended centerline out to a range of 10 nm.. . . the protection range and height of ils is 25 nm / 6 250 ft.. ...note 2 example of the glideslope vertical coverage calculation. for a glideslope of 3.3° the vertical coverage is as follows... . 0.45 3.3° = approx. 1.49° lower edge. . . 1.75 3.3° = approx. 5.77° upper edge
Question 213-35 : The vor radial an aircraft is on depends upon.. ?
The phase difference between the reference and variable phases.
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 ground station. the 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 213-36 : Which of the following errors affects the use of vor ?
Scalloping
Site error is caused by uneven terrain, for example, hills, trees, buildings and long grass near the transmitter. although the propagation has left the vor with ±1° accuracy, propagation error still exists.. propagation error is caused by the terrain and distance. at a certain range from the vor so called ‘bends’ or ‘scalloping’ can occur...vor scalloping is described as an imperfection or deviation in the received vor signal. scalloping causes the signal to bend as a result of reflections from buildings and terrain. scalloping also causes the course deviation indicator cdi to slowly or rapidly shift from side to side. scalloping has a negative effect on the accuracy of the navigation aids used.
Question 213-37 : How can a dme interrogator distinguish between its own reply pulse pairs and the reply pulse pairs of other aircraft in the area, using the same dme station ?
The pulse repetition frequency of the pulse pairs transmitted by the interrogator varies, for each interrogator, in a unique rhythm.
Dme uses the uhf frequency band, between 962 1213 mhz. the aircraft dme equipment radiated coded pulse pairs which is then received at the ground station, triggering the transponder to send a suitably formatted reply adjusted by +/ 63 mhz, after a delay of 50 microseconds. for each of the interrogation channels, two reply frequencies are allocated, one is 63 mhz higher than the transmission and the other 63 mhz lower. the reason for using pulse pairs is to ensure the receivers do no accept random single pulses or other transmissions that are not addressed for this type of communication. each pulse pair is spaced at 12 microseconds x channels or 36 microseconds y channels , and the space of each pair of pulse pairs is different between each group and is randomly unique to each transmission.
Question 213-38 : Which of the following alternatives is correct regarding audio and visual signals in the cockpit when passing overhead an ils middle marker ?
The outer marker, middle marker and inner marker all emit an amplitude modulated, horizontally polarised signal. the beacons operate at a 75 mhz carrier frequency.outer marker om. to provide height, distance and equipment function checks for aircraft on final approach.aural identification a 400 hz low pitch tone keyed in a form of 2 dashes per second .visual representation lights bluemiddle marker mm. indicated the imminence of transition to visual guidance. often defines the decision point.aural identification a 1300 hz medium pitch tone keyed in a form of alternating dots and dashes with 3 dashes per second ... visual representation lights amberinner marker im. indicates the imminence of arrival above the threshold.aural identification a 3000 hz tone keyed continuous dots at a rate of 6 dots per second ...... .visual representation lights white
Question 213-39 : Of the approach aids listed below, which option correctly identifies those that use the vhf band..1. locator..2. localiser..3. outer marker..4. glide path ?
Only 2 and 3
Locators operate on a frequency between 190 and 1750khz lf and mf. localiser operates on a frequency between 108.10 and 111.96 mhz vhf. marker beacons operate on a frequency of 75 mhz vhf. glide path operates on a frequency 328.6 and 335.4 mhz uhf
Question 213-40 : Middle marker beacons of an ils transmit at.. ?
75 mhz.
All ils marker beacons operate on 75 mhz vhf thus no frequency selections are necessary for the pilot and radiate a fan shaped field pattern giving to the pilot an indication of range from the threshold. the purpose of the markers is to provide range information while on the approach. they transmit an almost vertical beam. almost all installations are equipped with an outer marker and a middle marker. category 2 or 3 ils may be equipped with an inner marker as well. audio and visual signals in the cockpit will indicate when the aircraft is passing overhead. in many installations, marker beacons are being replaced or supplemented by the use of a dme associated with the ils...the outer marker is located approximately 3.9 nautical miles from the runway threshold and is aligned across the front beam of the localiser. its purpose is to provide height, distance and equipment functioning checks to aircraft on final approach. it is modulated at 400 hertz and keyed to transmit dashes continuously at a rate of 2 per second...the middle marker is aligned across the front beam of the localiser and is situated approximately 1050 metres from the runway threshold. its purpose is to indicate the imminence, in low visibility conditions, of visual approach guidance. this marker is modulated at 1300 hertz and keyed to transmit alternate dots and dashes · · · . the rate is 2 dashes and 6 dots per second. an aircraft on the glide slope over the middle marker should be roughly 200 feet above the touchdown zone elevation...the inner marker is modulated at 3000 hertz, identified by a keyed continuous signal of 6 dots per second · · · · · and is located 75–450 metres from the runway threshold...summary... . outer marker identifies glideslope intercept or the final approach fix light flashes blue. . . middle marker identifies decision height light flashes amber. . . inner marker identifies decision height for a cat ii ils light flashes white
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