Daily Revision Flashcards
Modulation
Process of superimposing audio frequency or information on to carrier wave.
NDB
Non directional beacon
Emission code: Non A1A and Non A2A
VOR
very high frequency (VHF) omni-directional range.
Basically, VOR stations broadcast a three-letter identifier in Morse code. All are oriented to magnetic north and emit beams as radial navigation. Therefore, 360 radials go out from every station.
VHF frequency range, which is between 108.0 MHz and 117.95 MHz.
From 108-112MHz
Localizer: Odd Frequencies
VOR: Even Frequencies
From 112- 117.95 MHz
All Frequencies are exclusively for VOR
Any aircraft with a receiver can confirm its position and remain on course. VORs are accurate to within one degree.
Pilots can positively identify a VOR by its Morse code identification.
This navaid is subject to line-of-sight limitations.
Ground stations use a specialized antenna system. This transmits an amplitude modulated as well as a frequency modulated signal.
Accuracy- +-5 Deg
Emission Code: A9W
Polarozation: Horizontal
Propagation : Line of sight
Working Principal: Bearing by phase comparison
Station Identification: Three letter morse code transmitters after every 10 seconds.
Two types of VOR:
1. C VOR - Conventional VOR
2. DVOR - Doppler VOR
C VOR - Conventional VOR
Reference signal is constt in all directions which is freq modulated @ 30Hz
Polar Diagram: Circle
Variable signal is rotated around station, varying phase & amplitude modulated @ 30 Hz.
Polar Diagram: Figure of eight
Combination of both Polar diagram: LIMACOM
Now airborne equipment will receive both signal & measures the phase difference between two signals & interprets the result as a RADIAL from the station.
Radial: Magnetic track radiating out from the station.
A/C Equipments:
1. Aerial: To recieve horizontally polarized signals transmitted from ground.
2. Reciever: Compares reference & variable signals from selected VOR to detect phase difference( Radial/ QDR).
3. Frequency Selector
4. Ident: Switch on the indent button to listen to morse code.
5. VOR Indicator: Shows 4 components
i) Omni Bearing Selector(OBS)
ii) To/ From Indicator
iii) Course Deviation Indicator:
Displays 5 dots either side
Each represents 2 degree deviation.
Total 10 degree deviation eaither side.
iv) Failure Warning Flag: Appears when
Failure of a/c recieving equipment
Failure of ground station equipment
Signals are too weak
While crossing cone of confusion
ERRORS OF VOR
Site Error
Airborne equipment error
Propagation Error
Beacon alligment error
Pilotage error
2. DVOR : Doppler VOR
Everything is same except minimised site error
It has total 51 aerials: 1 in centre, 50around it.
The aerial at center is reference aerial which is Amplitude Modulated @ 30Hz
The variable signal is frequency modulated @ 30 Hz (anticlock wise)
This is the basic difference between C VOR & D VOR.
C VOR Reference Signal Frequency Modulated Variable Signal Amplitude Modulated
D VOR Reference Signal Amplitude Modulated Variable Signal Frequency Modulated
How do pilots do a VOR check before their IFR flights?
VOT signal
VOR checkpoint
Dual VOR check
Airborne VOR check
Advisory service
Air Traffic Advisory Service is a service provided within advisory airspace to ensure separation, insofar as practical, between aircraft which are operating on IFR flight plans.
Alerting service
Shall be provided:
• for all aircraft provided with air traffic control service;
• as far as practicable, to all other aircraft having filed a flight plan or otherwise known to the air traffic services; and
• to any aircraft known or believed to be the subject of unlawful interference.
Manoeuvring area - defined as the section of an airport intended for take-off, landing, and the ground movement of aircraft, with the exception of aircraft aprons. Includes Taxi and Runway
Movement area- Includes APRON, Taxi , Runway
BASIC RADIO THEORY
Radio waves travel at the speed of light:
• c = 3 x 10 power 8 m/sec
• Frequency (f) - Number of complete cycles per second. Measured in Hertz (Hz).
1 cycle per second = 1 Hz
• 1 kHz = 10 power 3 Hz
• 1 MHz = 10 power 6 Hz
• 1 GHz = 10 power 9 Hz
• Wavelength (lambda) - Distance travelled in one complete cycle. Measured in metres.
• Time period (T) - Time taken to complete once cycle. T = 1 / f
• с = lambda X f
• Low Frequency = Long Wavelength
• High Frequency = Short Wavelength
Ideal antenna length is ½ the wavelength.
• If not possible, then 1/4, 1/8 etc will do.
MODULATION
• Modulation adds information to otherwise empty carrier wave.
PHASE DIFFERENCE
• Can only be measured when the signals have the same frequency (or wavelength).
POLAR DIAGRAMS
1. Omnidirectional
2. Directional (Inc unwanted side lobes)
• Applies to both Tx and Rx aerials.
MODULATION TYPE 1 - KEYING
• Interrupting the carrier wave to give morse code.
• Will temporarily interrupt the nav aid output in order to tx the morse code.
MODULATION TYPE 2 - AM
AM: amplitude modulation.
amplitude of the carrier wave is varied in accordance with the audio signal amplitude.
• Carrier wave frequency is kept constant.
• Oldest method apart from keying.
• Small amplitude areas give a weak signal that is prone to interference (especially since it operates in low frequency spectrum)
• Modulation circuit requires extra power to vary the amplitude.
MODULATION TYPE 3 - FM
• FM = Frequency Modulation
• Frequency of the carrier wave is varied in accordance with the audio signal amplitude.
• Carrier wave amplitude is kept constant.
• A +ve amplitude = higher frequency
• A -ve amplitude = lower frequency
• FM TX’s are simpler and cheaper than AM
• Lower modulation power required
• Constant amplitude = stronger
VHF operation = almost static free
• Horizontally polarised so suffers less from weather induced static (vertically polarised)
• Receivers are more complex.
Wider frequency band required.
MODULATION TYPE 4 - PULSE
• Radio wave is switched on and off at regular intervals, effectively forming pulses of radio energy.
• Use in radar.
Transmits O’s and 1’s effectively.
AM SIDEBANDS
• Whenever a carrier is AM modulated by a frequency lower than itself, sidebands are created.
• Carrier Wave = 500 kHz, Audio Freq = 4 kHz
• 4 kHz is filtered out.
• 496 kHz / 500 kHz / 504 kHz output
• Passband is a filter used to get rid of unwanted frequencies so bandwidth can be reduced.
• Single Sideband (SSB) - Often only 1 of the outputs is TX’d. The sideband carries the information rather than the carrier.
• With all TX power focused on one sideband, range is increased.
• FM has many more sidebands than AM.
Radio waves aKa Electromagnetic waves.
Consist of 2 Components: Electric and Magnetic.
Both components will be perpendicular to each other.
The electrical and magnetic components of a radio wave travel at right angle to each other that is perpendicular to each other and in the direction of propagation.
• Plane of electrical component = plane of polarisation.
• Transmssion from vertical aerial gives a vertical electric component and horizontal magnetic component.
• Transmission from horizontal aerial gives horizontal electrical component and vertical magnetic component.
• In circular propagation, both components spin about the axis of advance.
HF COMMS & HF VOLMET
• Use single sideband
• HF SSB = J3E
FREQUENCY SPECTRUM
• Frequency range repeats (kHz/ MHz / GHz)
3-30
30 - 300
300 - 3000
• Wave-length can be derived with C = lambda x f
EMMISSION CODES
• 1st = Type of modulation
• 2nd = Nature of modulating signal
• 3rd = Type of information transmitted
VHF DIRECTION FINDING
• GDF mainly operates in the VHF and UHF bands.
• Since UHF is rarely used in civil world, GDF is commonly referred to as VDF (VHF
Direction Finding).
• Can also operate in MF and HF bands but very rare.
VDF AERIALS
• Use either Adcock or Doppler aerials.
• Doppler is the most common and the direction of the incoming radio wave is calculated by the phase of the Doppler shift.
• Aerials are vertically polarised.
FREQUENCY SPACING
25 kHz = “Frequencies”
8.33 kHz = “Channels”
VDF PROCEDURES
• QDL - Series of QDMs are given.
• Pilot interpreted
• QGH - Heading and heights are issued to the aircraft to maintain the published pattern.
• ATC interpreted
DIRECTION FINDING Q CODES
• QDM - Magnetic to the station
• QDR - Magnetic from the station
• Radials go outwards
• QUJ - True to the station
True to the union jack
• QTE - True from the station
• Cutey from ATC
VDF CLASSES
• Class A: +- 2 Degrees (Not normally used)
• Class B: +- 5 Degrees
• Class C +- 10 Degrees
• Class D: worse than 10 Degrees
VDF RANGE FACTORS
• Line of sight limitations - Tx, Rx and terrain height.
Power of Transmitter
Sensitivity/ quality of receiver
• Range may be increased by duct propagation.
• Range may be decreased by sub-refraction (due to temperature and humidity).
VDF ACCURACY FACTORS
• Equipment errors
• Propagation errors (reflections, refraction, duct propogation etc)
• Site Errors (Reflections from objects near to the receiver)
• Multipath Errors (Reflections from objects between aircraft and ATC)
• Crossed transmission
RELATIVE BEARING
• The ADF will measure the relative bearing of an NDB from the nose of the aircraft.
• QDM = MH + RB
ADF DISPLAYS
• Fixed RBI (Relative Bearing Indicator) will require use of mental maths to obtain QDM.
• RBI (With Moving Compass Card) will show QDM when current MH is set on the display.
• RMI (Radio Magnetic Indicator) will always show QDM as it’s linked to the compass.
NDB CHARACTERISTICS
• Omnidirectional.
Vertically Polarise.d
• LF & MF Bands (190 - 1750 kHz)
• Surface Wave Propogation (Sky waves could interfere at night)
• Range: 10 nm - 500 nm
• Power Range: 25 Watts - 10 Kilowatts
• Ident: 2/3 More Code Letters
: NON A1A- Unmodulated, human ears can’t hear, BFO(Beat frequency Oscillator is used) 50 nautical miles more
: NON A2A- AM modulated, 50 NM less
LOOP AERIAL
• Different orientations of the aerial will give different voltage differentials
: Maximum differential when parallel.
Minimum differential when perpendicular.
SENSE AERIAL
• Required in order to resolve the direction as two positions can give the same differential.
CARDIOID POLAR DIAGRAM
Loop ( figure of *8) + Sense (circular) = Cardioid
The direction of zero signal strength will point towards the NDB.
• Due to 0 V, ident must be performed regularly to check NDB is still active.
FIXED LOOP THEORY
• The rotating loop is replaced with a pair of fixed loops 90 degrees apart.
• An electro magnetic field is set up.
NDB RANGE
: 200 - 500 Nm most common
Increase TX transmitter power = Increase range
• Increase frequency = Decrease range
• NON A2A used power for modulation so has a lower range than NON A1A.
ANT SWITCH ( REC/ OMNI/ SENSE)
• Sense aerial only is used.
• Needle should point to 90 degrees
Once deselected, needle should point to beacon.
BFO SELECTOR
• Used to ident the NoN A1A (Unmodulated)
Non A2A are amplitude moduted with an audio signal so no BFO required to ident.
• NDB frequencies are outside the audio range so an appropriate sideband must be created to hear the ident.
• A frequency of 299 kHz (for example) could be mixed with an NDB of 300 kHz to produce a beat frequency of 1 kHz.
MANUAL TUNING
• Another use of the BFO is in the manual tuning of an ADF.
• Required for both NON A1A and NON A2A.
ADE SELECTION PROCEDURE
: Check aircraft within NDB stated range
• Select frequency
• Select ANT to test
• Select BFO as required **
Check Ident
Select ADF
** Even if not required for ident (if NDB was NON A2A), the BFO will always produce a higher quality signal as the loop aerial is removed. It can be used therefore to check interference.
NDB ERRORS
MUTUAL INFERENCE
• NDBs transmitting on the same or similar frequency can lead to mutual interference.
• Cannot use them inside the overlapping area.
• Stick to the published range (applicable to day only).
NIGHT EFFECT
• Skywaves from other NDBs by night can cause interference.
• Minimised by listening to the BFO (to check clean signal) and identing.
STATIC (PRECIPITATION)
• Dust and water droplet rub against aerial creating static.
• Causes PD disruptions.
• Must make physical contact with aerial.
STATIC (THUNDERSTORMS)
• Nearby thunderstorms will cause ADF to point towards lightning strikes.
• Just vicinity (not direct contact) sufficient.
MOUNTAIN / MULTI PATH EFFECT
• Reflection / refraction of the signal in the mountainous areas.
COASTAL REERACTION
• Aircraft RBI points at 270° rather than 220°
• When plotted on the map, aircraft appears ‘closer to the coast’ than in reality.
• Minimised by flying higher or moving NDB closer to the coast.
LACK OF FAILURE WARNING
0V ( as used in cardioid) is also present WhenNDB is off or in a cone of silence (above NDB)
QUADRANTAL EFFECT
• A signal arriving at 45º to aircraft structure will be bent by the metal framework construction.
• Normally fixed internally so no longer an issue.
FINDING DISTANCE FROM NDB
(Elapsed Time (Mins) x Groundspeed)/ Change In Radial
DIP ERROR
• When in a banked condition, the PD is distorted.
Needle will dip towards the lower wing.
Approx 10° in a light aircraft although varies from aircraft to aircraft.
ACCURACY
NDB Accuracy: +- 5° (Day)
ADF Frequency : +-6.9°
NDB LOCATOR
A low powered NDB
• Usually installed as a supplement to ILS at the sites of the outer and middle markers.
VOR FREQUENCIES
• 108 - 112 MHz: VOR & ILS
• 40 Channels Each
• ILS Frequency if first decimal digit is odd
(108.10 MHz. & 108.15 for example)
• 108 - 118 MHz: VOR
• 120 Channels
• 50 KHz spacing
• Total VOR Channels = 160
EMISSION TYPE
A9W
: Horizontally Polarised
Less noise as atmosphere is vertically polarised.
• 2 Methods of IDENT
Keyed AM morse code every 10 secs
• Voice
VOR TYPES
• Terminal (108 - 112 MHz)
• Up to 50 watts
• 25 - 100mm
• 40 channels
• Enroute (112 - 118 MHz)|
• Up to 200 watts
• 200 nm (Max 300 nm)
• 120 channels
• Broadcast VOR
• Normally a terminal VOR
• Transmit radial & ATIS
• TEST VOR
• Transmits just 360 radial.
• +- 4 degrees requires servicing
RMI DISPLAY
• Tail of needle = QDR
• Head therefore points to QDM
CVOR (CONVENTIONAL VOR)
• Signal 1: Reference Signal
• Omni-directional
• Transmitted on a sub carrier
• FM modulated at 30 Hz
• Signal 2: Variphase Signal
• Directional
• Transmitted on main carrier wave
• Appears AM modulated at 30 Hz
• Rotates at a rate of 1800 грm
• Reference + Variphase = Rotating Limacon
• The phase difference is measured when the voltage drops on the rotating limacon.
• The phase difference is equal to the radial (QDR)
• Zero phase difference when on the 360 degree radial.
• Does not drop to zero like cardioid.
SITE ERROR
• Obstacles near the transmitter cause radio waves to be reflected.
• Limacon pattern is disorted and amplitude does not rise / fall in the predicted manner.
CONE OF CONFUSION
• Overhead VOR
• Can result in flickering of the ambiguity indicator (to / from flag)
• Possible failure flag (often prevented)
TERMINOLOGY
• CDI = Course Deviation Indicator
• OBI = Omni Bearing Indicator
• OBS = Omni Bearing Selector
RML VS CDI
• RMI shows bearing
• CDI shows displacement
DISPLACEMENTS DOTS
• Each Dot = 2 Degree Displacement
• The outside of a centre circle if present counts as one dot.
• Full Scale Deflection = 10 Degrees
DOPPLER VOR
• Signal 1: Reference Signal
• AM Modulated
• Transmitted on main carrier
• Signal 2: Variphase Signal
• AM Modulated
• Transmitted on sub-carrier
• The variphase signal is transmitted on 50 different aerials in turn around
the reference signal.
• Doppler shift is used to calculate phase
difference.
Doppler vs CVOR
• A larger aerial is required to reduce site error in a CVOR.
• Impractical to rotate a large aerial
• Doppler aerial is much more accurate and there is very little site error.
FAILURE FLAG
• Receiver failure
• Transmitter failure
• Ambiguity Indicator Fail (often prevented)
• Signal too weak / out of range
VOR MONITOR
• Will power-off VOR or remove ident when:
• Bearing exceeds ‡ 1 degree
• Signal strength drops by 15% or more
• VOR monitor fails
VOR RANGE FACTORS
• Transmitter Power
• Line of Sight Limitations
• DOC
• Nature of Terrain
VOR ACCURACY FACTORS
• Site error( Reduced by Doppler)
• Propagation Error
• Irregular terrain causing oscillations
• Slow Oscillations = Bends
• Rapid Oscillation = Scalloping
• Scallops cannot be followed
• Airborne equipment error
• Interference error( DOC / Below LOS )
• Irregular terrain causing oscillations
OVERALL VOR ACCURACY
• +-5 degrees 95% of the time
• Worst case +- 7.5 degrees
DISTANCE BETWEEN VORS
• Distance required to ensure no conflict between VORs will be range *2
VOR DISTANCE - AIRWAYS
• Track Error = (Distance Off / Distance Gone) X 60
• If VOR accuracy is +- 7.5 degree, what’s the max distance the VORs can be apart assuming the airway is 10 nm wide?
• 7.5 = (5 / Distance Gone) X 60
• Distance Gone = 40 nm (Midway Point)
=> Max Distance is 80 nm
VARIATION & VOR /ADE
• For VOR use variation at VOR beacon.
• For ADF use variation at aircraft .
GREAT CIRCLE
• Flying along a VOR radial, you will be following a great circle track
REFRACTION
• Radio waves are refracted when travelling obliquely from a medium of one density to another of different density.
• Due to different velocities there is a slight change of wavelength.
• Low to high density = slows down and bends towards the normal.
• Types of refraction:
• Coastal (Land to sea. Flying higher or moving beacon towards coast will reduce effects)
• Atmospheric (Density change with altitude.)
• Ionospheric
REELECTION
• Radio waves bounce off a solid surface.
• If two signals arrive at the same time but out of phase, there can be fading / temporary losses.
DIFFRACTION
• When a radio wave passes a solid object, radio energy is scattered.
• Allows radio waves to be received behind a mountain.
SURFACE ATTENUATION
• As a radio wave passes over a surface it loses energy.
• Higher frequencies are more susceptible as they hit the surface more often.
IONOSPHERIC ATTENUATION
• The ionosphere and particles in the atmosphere can absorb and block a radio wave.
ATMOSOHERIC / RADAR ATTENUATION
• When radar energy strikes water droplets, some energy is absorbed (and attenuated) and some is reflected.
DOPPLER EFFECT
• + VE Doppler Shift: If the distance between the source and the receiver is reducing, the received frequency appears greater than that transmitted.
• Occurs because more waves are detected than if stationary.
• - VE Doppler Shift: Distance increasing / frequency appears lower.
• Actual wavelength stays the same.
ATTENUATION & REFRACTION BY FREQUENCY
• Top Column = A - RADAR
BASIC RADIO CIRCUIT
• Human Ear: 20 Hz. To 20 kHz
PROPOGATION
• Describes the path of the radio wave from the transmitter to receiver.
• VLF / LF /MF / HF Propagation: Surface Wave, Sky Wave
• VHF / UHF / SHF Propagation: Direct Wave
DIRECT WAVE
Essentially line of sight
Height of Tx + Rx
• Power of Tx
• Height of intervening high ground
Max Range (nm) = 1.23(root height of transmitter + root height of receiver )
• Range can be reduced if required by lowering the power of the transmitter.
• Space waves = Direct + Reflected + Sky
SURFACE WAVES
Due to diffraction and surface attenuation
Attenuation slows the bottom of the wave giving it a forward tilt allowing it to follow the curvature of the earth.
• Attenuation is reduced over the sea (waves travel twice as far)
• Lower frequencies have a longer range as attenuation is less.
• Drawbacks are low efficiency aerials (not ½ wavelength), static and transmitting power required.
SKY WAVES
• When radio signals are refracted by ionosphere (bent) sufficiently to return to earth.
• Lower frequenciesare refracted more.
Ionosphere is approx. 50 - 500 km.
3 Layers to the ionosphere:
Higher frequencies are refracted by the higher layers but anything VHF or greater passes straight through:
F Layer - HF
• E Layer - LF / MF
• D Layer - VLF
• At dawn / dusk there may be no signal due to re-ionisation.
SKY WAVES AT NIGHT
• Changes at night:
• D layer disappears
• E & F layer increase in height
• An 8 MHz frequency will go higher in the atmosphere at night due to layers increasing in height.
• In order to avoid signal going out of range, using approx. half the frequency will cause it to refract more and stay in range.
SKY WAVE TERMINOLOGY
• Critical Angle - Minimum angle at which a radio wave will refract and return to earth.
• Anything less = no refraction
• Anything more = increase skip distance
• Skip Distance: Distance between transmitter and the point where the first sky wave arrives.
• Dead Space - Area between the limit of the surface wave and the 1st sky wave.
• Mainly HF band.
• Minimised with a lower frequency.
SKY WAVE FREQUENCY INCREASE
• Less refraction at a higher frequency.
Critical angle increases
Skip distance increases
MF / LF SKY WAVES
• MF / LF gets attenuated too much during the day and there are no skywaves during the day.
• Night is fine as attenuation is less.
Can cause interference by night with surface waves (eg NDBs) so Tx power may be reduced at night.
RANGE OF SKYWAVES
• Transmitter Power
• Quality of receiver
• Frequency transmitted
• State of ionosphere
DUCT PROPOGATION
• Created by a temperature inversion and / or rapid decrease in humidity with height.
• Causes super refraction and VHF and above can have unexpected ranges.
• Layer is normally no more than 1,000 ft
SIGNAL-TO-NOISE RATIO
High SNR when amplitude of wanted signal is greater than that of unwanted signal
ILS CHARACTERISTICS
• A8W
• Horizontally Polarised
• VHF Band (108 - 112 MHz / Odds)
• 3 Letter Morse Ident
LOCALISER
• VHF Band
• Located 300m beyond end of the runway.
• Left lobe AM modulated at 90 Hz
• Right lobe AM modulated at 150 Hz
• Difference in Depth of Modulation (DDM) determines position of localizer needle.
• Equal depth = centreline
• Linear increase in DDM from centreline
BACKBEAM
• Can be used to provide centreline guidance after takeoff or during a go-around.
• Backbeam approaches are non-precision
• No glideslope indication
• Less accuracy
• No markers
• Needle sense reversed
GLIDESLOPE
• UHF Band (329 - 335 MH)
• Abeam TDZ (300m from threshold)
• Offset 120m from centerline
• Top lobe AM modulated at 90 Hz
• Bottom lobe AM modulated at 150 Hz
• Lateral Range
• 8 degree either side of centerline
• Extends 10nm from runway
• Vertical Range
• Bottom of lobe at 0.45 x G/S Angle
• Top of lobe at 1.75 x G/S Angle
• EG / 3º glideslope extends to a distance of 10nm, 8 degree either side of centreline with a vertical coverage between 1.35° and 5.25°
ILS MARKERS
• All markers transmit at 75 MHz but have different pitch.
OBS / COURSE INDEPENDENT
• Localiser needle will indicate deviation in correct sense regardless of OBS / Course selector setting
• Measures DDM rather than phase difference.
• Good practice to set RWY QDM however.
SCALE DEFLECTION
• Localiser
• Each dot 0.5°C
• Full scale is 2.5°C
• Glideslope
• Each dot 0.14°C
• Full scale is 0.7° C
• Once established, max ½ scale deflection.
FAILURE INDICATIONS
• Localiser Fail = NAV Flag
• Glideslope Fail = G/S flag
ILS MONITOR
• If installed, a second transmitter will be brought online.
• If no second transmitted:
• Transmissions stopped
• IDENT removed
• Maintenance alerted
FALSE GLIDESLOPE
• The lower 150 Hz lobe is sometimes reflected from the ground.
• Approach is always made from below glideslope to avoid intercepting the false one.
BENDING
• Bending of the localiser and glideslope can occur due to other aircraft and vehicles.
• Critical Area established for CAT I
• Sensitive Area established for CAT II / III
ILS CATs
• CAT I = 200 ft DH (Guidance to 200ft)
• CAT II = 100 ft DH (Guidance to 50 ft)
• CAT III = 0 ft DH
• CAT II + CAT III require autopilots.
RATE OF DESCENT
ROD = Glideslope x (Groundspeed/ 60) × 100
GLIDESLOPE HEIGHT
G/S Height = G/S Angle x Range x 100
FM IMMUNITY
• FM transmission near to 108 MHz may interfere with ILS LOC & G/S.
• Can lead to erroneous localiser readings.
• Moden aircraft are fitted with FM filters to filter out this interference.
———————————————————————————-
WHY MLS?
• An attempt at overcoming the shortcomings of the ILS which are:
• Expensive
• Bending of the beam
• Poor runway occupancy during LVPs
• Whilst it was being invented however, the GPS came along.
COVERAGE
• Approach Azimuth: 40° either side of centreline extending to 20 nm
• Elevation: 15º to 20,000 ft
FREQUENCIES
• 5031 -5091 MHz (SHF)
• 200 Channels (500 - 699)
• Azimuth and elevation use the same frequency.
• DME is on a different frequency but frequency paired.
PRINCIPLE OF OPERATION (TRSB)
• Time Reference Scanning Beam
• The difference between a TO Scan and FROM Scan is calculated and the aircrafts position can be determined.
• In the azimuth example below, there is less of a gap between the TO and FROM scan when furthest south.
MULTIPLE GLIDE PATHS
• No fixed glide path exists as with an ILS.
• The pilot can choose any glide path within a range of range of 0.1 degree - 15 degree
• Suited to a wide range of aircraft.
MULTIPLE & VARIED APPOACH PATHS
• Approach paths that vary by 60° or more from the direction of the associated runway can be used.
• Allows for simultaneous approaches to made along different paths (improved airspace capacity).
• A single MLS can be used to cover multiple runways.
CONTINOUS RANGE INFORMATION
• Co- located with PDME (Precision DME)
• A PDME failure will require a straight-in approach to be flown.
OTHER ADVANTAGES
• Simpler to install than ILS
• Not sensitive to terrain issues
• Virtually immune from scalloping caused by vehicles and other aircraft.
• Free from weather- induced error.
• No false- glide paths.
GROUND - AIR DATA TRANSFER
• Transmits time To and FROM scan.
• 4 second morse at 10 minute interval.
• Transmitter locations, airport information and performance levels can be also be transmitted.
MULTIPLEXING
• Transmitters transmits continuously.
• Receiver alternates between scanning elevation, azimuth, backbeam, data etc.
ACCURACY
• Stated accuracy (95% of the time) at 200 ft above MLS datum for a runway 10,000 ft long with a 3° glide slope.
• Laterally: +- 50 feet
• Vertically: +-12 feet
CALCULATING RANGE
• Measuring the time taken for a pulse of radio energy to return to the antenna will allow us to calculate the distance.
• Radio waves travel at a known speed of 3 x 10 power 8 m/s (metres per second) or 300 m/usec (metres per micro-second)
RADAR MILE
• 12.36 m/usec
• Time taken for transmission to travel 1 nautical miles out and 1 nautical miles back.
RADAR DEFINITIONS
• Pulse Length
• Duration of the pulse in microseconds.
• Pulse Width
• Length of the pulse in metres
• Pulse Repetition Interval (PRI)
• Time interval from start of one pulse to the start of the next.
• Pulse Repetition Frequency (PRF)
• Number of pulses transmitted per second.
PRI & PRF RELATIONSHIP
PRI = 1 / PRF
PRF = 1 / PRI
THE RADAR CYCLE
• Pulse of energy is transmitted for the duration of the pulse length.
• Once transmitted, the transmitted is turned off and the receiver is turned on.
• The receiver now waits for the echo’s to return.
• The “listening phase” is known as the recovery period.
• After the PRI is reached, it switches from RX to TX mode and another pulse is sent.
• Note that for the majority of the time, the radar is listening for echoes rather than transmitting.
• Pulse Length < PRI
POWER & RANGE
• A normal transmitter requires 4 times the amount of power to double the range(2 power 2)
• Since RADAR must travel there and back, 16 times the original transmitter power is required to double the RADAR Range ( 2 power 4)
MAX RANGE
• Determined by the PRI.
• A long recovery period is required for a range RADAR. This ensures there is sufficient time for the pulses to return before transmission begins again.
• So, Longer Range = Longer PRI
• Distance = Speed x Time
• Max Range = C x PRI x ½
MIN RANGE
• Determined by Pulse Length.
• When the target is close to transmitter, there is a risk it may return the radar energy before the transmitter has switched to RX mode.
• So, Shorter Range = Shorter Pulse Length
• Distance = Speed x Time
• Min Range = C x Pulse Length x ½
OR…
• Min Range = Pulse Width x ½
RADIAL RESOLUTION (PULSE WIDTH)
• A large pulse width may cause targets that are close together to return as a single contact.
• EG/ A pulse length of 1 usec will stretch the target by 150 metres. If another aircraft is within 150 metres they will merge on the display.
• A short pulse width will therefore be required to improve radial resolution.
• Shortening pulse width however reduces the time the target is illuminated by the pulse, thus reducing the chance of a good return.
AZIMUTH RESOLUTION (BEAM WIDTH)
• A narrow beam will improve azimuth resolution.
• A narrow beam can be produced with higher frequencies. However, a big antenna is required to achieve a higher frequency which will require a lot more power.
WAVELENGTHCONSIDERATIONS
• Short wavelength (high frequency) will be subject to greater attenuation.
• Suited for weather radar
• Long wavelength (low frequency) will be subject to less attenuation.
• Suited for ATC radar as transmission are less affected by cloud and precipitation.
ANTENNA TYPES
Parabolic Antenna - Old Type
Phase Array Antenna - New Type
• Requires less power as arrays are powered individually rather than all together at once.
SECONDARY RADAR (SSR)
SECONDARY RADAR
• Ground transmitter requires less power
• Signal only needs to reach aircraft
• Small aerial can be used on aircraft
• Aircraft emits omnidirectional reply
• Echoes Eliminated
• Only target replied are accepted
• Ground transmitter requires less power
• Signal only needs to reach aircraft
• Reply strength independent of target reflection properties.
• Replies can be coded with additional information
SYNCRONISITY
• Secondary radar normally transmits its pulse once a primary return has been received.
• Minimises transmission time on 1030 MHz which is the common SSR frequency.
MOVING TARGET INDICATOR (MTI)
• Only moving targets (identified by Doppler shift) are displayed on the radar screen.
• Fixed objects (buildings etc) are therefore filtered to reduce clutter.
RADAR APPROACHES
SURVEILLANCE RADAR APPROACH (SRA)
• Uses the ASR (Aerodrome Surveillance Radar)
• Provides azimuth information only.
• Normally terminated 2 nautical miles from touchdown.
• “You are right of the centerline, turn left two degrees. At 3 miles from touchdown you should be passing 1200 feet. 3 miles now.”
PRECISION APPROACH RADAR (PAR)
• Utilises a scanning beam
• Provides both azimuth and glide slope information.
• Both SRA & PAR are normally military approaches and only used by civil traffic in case of emergency.
OTHER RADAR TYPES
SURFACE MOVEMENT RADAR
• Allows control of aircraft and vehicles moving on apron, taxiways and runways.
• Operates in the SHF band.
• EHF was blocked by precipitation.
ADS
• Automatic Dependent Surveillance
• Aircraft identifies its position using GPS then transmits this to ATC.
• Useful for areas without radar coverage / obstructions.
AIRBORNE WEATHER RADAR
OPERATION PRINCIPLE
• Uses primary RADAR to detect reflection from water droplets.
• Whilst the wavelength would ideally be ½ the average water droplet size, this would create a very high frequency and attenuation would be too great. A compromise is therefore used.
AWR FACTS
• Frequency: 9.75 GHz (SHF)
• Wavelength: 3 cm
• Beam Width = 3.5 degree → 5 degree
ANTENNA TYPE
• A phased array antenna is used.
• The narrow beam required can be produced without requiring a large antenna and high power consumption.
• phased array also produces less side lobes.
AWR COLOURS
• Green / Yellow / Red / Magenta.
• Colour gradient indicates turbulence.
FALSE ALLEY
• When TS is present behind another cloud, radar attenuation can cause no return from the clouds behind.
• Can create the impression of a false alley on the radar display.
STABILISER (STAB) FUNCTION
• With STAB ON, the antenna is stabilised in pitch and roll by gyros.
• Without STAB, the radar could overscan (miss the cloud) in a climb for example.
WX MODE & WX/ TURB MODE
• With WX/TURB mode, the doppler function is activated and turbulence detection is available.
• High PRF is used so range is reduced to about 50 nm.
GAIN CONTROL
• Gain controls the amplification of the radar.
• Gain amplifies input signals whereas volume amplifies output signals.
• It is manually adjusted when in MAP mode.
• Auto is selected when in WX mode in order to allow the STC to function.
STC (AUTO GAIN)
• Sensitivity time Control.
• Active when in WX mode and gain on AUTO.
• Without STC, clouds which are closer will appear stronger than those further away (due radar attenuation even though the intensity may be the same.
• Applies less gain to closer returns in order to pain a more accurate picture.
• Operates to a range of 60 nautical miles.
TILT
• Tilt is +-15 degree.
• Scanning too low can cause relected ground return to mix with weather return.
• Scanning too high could lead to overscanning.
MAP MODE
• New aircraft = Beam shape unchanged, STC deactivated and gain used manually to highlight terrain features.
• Older aircraft use a cosecant fan shaped beam.
• More power is deflected to the ground further away to provide a uniform picture.
CALCULATING HEIGHT OF CLOUDS
• Use the 1 - 60 rule
• Range 40 nautical miles.
• Cloud just disappears when 6 degree up tilt is set.
• STAB - ON
• Beam width 5 degree.
• Height of cloud = 14,000 ft + 12,000 ft = FL260
SECONDARY SURVEILLANCE RADAR
OPERATION PRINCIPLE
• Primary radar identifies that a target is present.
• Secondary radar then interrogates the target to obtain more information.
• The amount and type of additional information obtained depends on the SSR mode in use.
OPERATION PRINCIPLE
• Primary radar identifies a target is present
• Provides ATC with target return and trend information .
• Secondary radar interrogates the target to obtain more information.
o The amount and type of additional information obtained depends on the SSR mode in use.
• SSR will use primary radar principles to additionally derive the aircraft groundspeed.
SSR FREQUENCIES
• Transmits on 1030 MHz
• Receives aircraft replies on 1090 MHz
TRANSPONDER COMBINATIONS
• There are 8 power 4 = 4096 squawk code combinations available.
SQUITTER
• As well as replying to SSR interrogation, aircraft will send out information every second for use by other aircraft in TCAS.
INTERROGATION PROCESS
• By altering the PRI between Pulse 1 and Pulse 3, the transmitter can interrogate either Mode A or Mode C.
• By using these fixed PRI’s, there is less likely to be confusion from interference as the aircraft is only listening to the expected PRIs.
• Mode A (Transponder Code) = 8usec
• Mode C (Pressure Altitude) = 21 usec
REPLY PROCESS
• The aircraft will transmit 2 framing pulses 20.3 usec apart.
• In between these, are information pulses which supply ATC with the required information.
• This process is called pulse position modulation.
• IF IDENT is sent, it will transmit for 20 seconds after the second framing pulse.
SPECIAL CODES
• 7700 - General Emergency
• 7600 - Radio Failure
• 7500 - Unlawful Interference
• 2000 - Entering airspace from non SSR region
• 7000 - General Conspicuity
MODE C ACCURACY
• Pressure altitude is transmitted which is based on 1013 hPa.
• The height transmitted to ATC could be up to 50 ft different from the actual altitude due to rounding during transmission
• EASA allows a max discrepancy of 300 feet between reported level and readout.
SSR DISADVANTAGES
• Garbling
• Replies of 2 aircraft in close proximity overlap and result in random readouts.
• Fruiting
• Aircraft transmit omnidirectional
• Radar picking up the wrong reply since aircraft transmit omnidirectionally and on the same frequency.
• Antenna Shielding
• Aerial on bottom of aircraft is hidden from radar during a turn
• Ghost Targets
• Reflection from terrain
• Only 4069 Codes
SSR ADVANTAGES
• Longish Range
• No Clutter
• Reply gives range, bearing, height and speed
• Less power required
• Reduced comms
SIDE-LOBE SUPPRESION
• To allow aircraft to distinguish between the main lobe and side lobes, a second pulse is transmitted between P1 and P3.
• P2 is sent out omnidirectionally
• If the amplitude of P2 > P1 the aircraft can tell it is picking up a side lobe and will not reply.
• If the amplitude of P1 > P2, the aircraft will reply as it is genuinely being interrogated.
MODE S
MODE S ADVANTAGES
• Eliminates fruiting and garbling.
• Datalink allows for air - air / ground - air / air - ground data transmissions
• Provides TCAS enhancements
• Greater height accuracy (+- 25 ft)
INTERROGATOR CODES (IC)
• Each ground station has an interrogator code.
• IC = II + SI
• Il (Interrogator Identifier) = 15 codes
• SI (Surveillance Identifier) = 63 codes
AIRCRAFT IDENTIFICATION
• Aircraft are identified by the following means:
• 24-Bit ICAO Aircraft Address (AA)
• Hard coded into the transponder
• Aircraft Identification
• Flight Number / Aircraft Registration.
• Incorrect entry is the biggest problem with mode S
• Squawk Code
MODE S ALL-CALL
• Ground station sends out an all-call periodically in order to check for new aircraft entering its airspace.
• P2 pulse suppresses Mode A / C response.
• P3 is replaced by P6 which is a data-block.
• The data-block will include the ground stations IC code.
• Side lobe suppression achieved with P5
• On receiving the all-call for the first time, an aircraft will reply with the IC code and it’s AA (aircraft address).
• Ground station then locks out the aircraft and asks it not to reply to further all-calls for 18 seconds.
ROLL-CALL
• Once locked-out, the aircraft will only reply to selective interrogations.
• Inclusion of IC and AA in interrogations and replies reduces fruiting and garbling.
• Also prevents over interrogating (minimises transmission time on 1030 MHz and 1090 Mhz)
MODE INTERLACE PATTERNS
• 1/3 of time is spent on the all-call
• 2/3 of time is spent on roll-calls.
INTERMODE ALL-CALL
• Allows for ground stations to elicit response from both mode A / C aircraft and mode S equipped aircraft.
• P1, P2 and P3 as normal to interrogate Mode A / C aircraft.
• P4 pulse included at end which is recognised by mode S aircraft.
• Long Pulse = Mode S Reply Required
• Short Pulse = Mode S Reply Not Required
TRANSPONDER REPLY FORMAT
• 25 possible Mode S Reply forms.
• Message consists of a preamble followed by a data block.
LEVELS OF SURVEILLANCE
• Elementary Surveillance
• Identifications used to reduce fruiting and garbling.
• Enhanced Surveillance
• Additional downlink aircraft parameters (DAPs) are included to provide current state vector information.
• Groundspeed
• Track angle
• Turn Rate
• Roll Angle
• Vertical Rate
• Magnetic Heading
• IAS
• Mach No
• True Track Angle
• Future Developments
• Aircraft intention information
DME
DME CHARACTERISTICS
• Vertically Polarised
• PON
• UHF (962 - 1213 MHz)
• 256 Channels
• 126 X Channels (12 usec)
• 126 Y Channels (36 usec)
• Typical Range: 200 nautical miles.
FREQUENCIES
• Interrogator (located in aircraft) transmits on the DME frequency between 962 - 1213 MHz.
• Ground station replies with a frequency +-63 MHz different.
- JITTERED PRF
• Interrogator transmits a series of pulses in pairs.
• The interval between two pulses making a pair is kept constant.
• The interval between pairs of pulse however is randomly generated.
• Prevents fruiting - GROUND STATION REPLY
• On the +-63 MHz frequency, the ground station sends back any pulses received after a delay of 50 usec
3.RECEIVER
• The receiver on the aircaft is tuned to the +-63 MHz frequency and picks up all the replies from the ground station.
• Amongst all the replies, it searches for it’s interval pattern which was transmitted.
• Once a match has been found, it computes the range from the station.
Range =(Time Elapsed - Delay) / 12.36 (Radar Mile)
MODES
• Search Mode
• Before a ‘lock-on’ has occurred, the aircraft searches out to its max range in order to identify the presence of the DME ground station.
• This takes place at 150 pps
• If 15,000 pulses have been sent and no lock-on has occurred, it reduces to 60 pps|
• Tracking Mode
• Once lock on has occurred, 24 - 30 pps is used to reduce load on ground station.
• Memory Mode
• When signal drops out, memory mode is entered for 10 seconds.
• Range calculated based on last trend information,
• After 10 seconds and no further signal , search mode is re-entered.
BEACON SATURATION
• DME ground equipment is normally limited to 2700 pulse pairs per second (pps)
• If all aircraft were on search mode, only 18 aircraft could interrogate the ground station simultaneously (2700 / 150)
• If all aircraft were on tracking mode, 120 aircraft could interrogate simultaneously.
• In practice, most aircraft will be on tracking mode and a few on search mode.
• Average capacity = 100 Aircraft
OVER SATURATION
• In the event more than 100 aircraft try to interrogate the ground station, receiver gain is reduced.
• This results in the ground station only listening to those aircraft closer to the station which have a higher priority than those further away.
GHOST FREQUENCY
• Since civil pilots cannot tune UHF, a ghost VHF frequency is displayed on the charts etc.
• This is frequency paired to the correct UHF frequency.
CO LOCATED IDENTS
• Co-Located when VOR & DME within:
• 2000 ft (En-Route)
• 100 ft (Terminal)
• Idents of VOR and DME will be the same.
• VOR idents every 10 seconds.
• DME idents every 30 - 40 seconds.
• DME ident is at a higher frequency of 1350 Hz (2700/2)
SAME LOCATION IDENTS
• When in same location but too far apart to be ‘co-located’.
• Last letter of DME ident changed to a Z
SLANT RANGE
• A long ranges, slant range ~ plan range.
• When closer than 3x height
GROUND SPEED AND TIME
• A decrease in ground speed readout can be expected when nearing the beacon at a constant height.
• This is because the change in slant distance decreases closer to the beacon.
• On ILS, you are following a constant slant so this is not a factor.
ACCURACY
• Best accuracy when flying directly TO / FROM the beacon.
• Worst accuracy when flying abeam the beacon.
• Old Beacon accuracy (answer is +-):
0.25 nm + (1.25/100 x Distance)
• New beacon accuracy: +- 0.2 nm
• DME is more accurate than VOR except when directly overhead the beacon.
RNAV
RNAV TYPES
• Basic RNAV (B-RNAV) - +-5 nm 95% of time.
• Precision (P-RNAV) - +- 1 nm 95% of time.
ERROR TYPE
• With VOR ,the error is a radial error.
• With RNAV, the error is a cross track error.
NAVAIDS USED
• DME - DME most accurate.
• ADF not used in RNAV.
AUTO / MAN MODE
• In AUTO, NAVAIDs are selected and tuned automatically based on range/ geometry.
• Better to use two navaids that intersects at 90 degree.
GNSS
CONSELLATION
• 24 Satellites (21 Operational & 3 Spares)
• 1 Orbit - 12 Hrs
• 6 Orbital Planes with max of 4 per each plane.
• Cross EQ at 55º with 60° between planes.
• Height of orbit - 20200 km
PRINCIPLE OF OPERATION
• Signal sent to aircraft which includes the satellites position and time the message was sent.
• Aircraft can then calculate it’s distance from satellite.
• 3 Satellites required for basic position fix.
PSEUDORANGE
• The aircrafts receiver clock is inaccurate in comparison to the satellites atomic clock.
• Due to this error, the range obtained is termed pseudo range.
• This error is minimised by use of a fourth satellite to help obtain the correct timing information.
DATABASES
• Almanac - Positions of all satellites.
• Ephemeris - Position of individual satellite.
SEGMENTS
• User
• Control
• Space
CONTROL SEGMENT
• Manages performance of the system.
• Provides NAV DATA upload
o Almanac - Every 24 Hrs
o Ephemeris - Every 2 Hrs
• Monitors satellite constellation.
DATABASE SYNCING
• A ground station downloads the latest almanac database from the first satellite it finds after being powered on.
• This gives it a rough idea as to the location of
other satellites.
• Once it has located the other satellites, it will download their individual ephemeris data.
IDENT CODES
• C/A - Coarse Acquisition Code (Civil)
• P - Precision Code (Military)
FREQUENCIES
• Satellites / Space Vehicles (SV) - SHF
• Users = UHF .
• Satellites transmit on L1 and L2 at the same time.
• Military users can compare L1 and L2 in order to calculate the depth of the ionosphere and obtain better accuracy.
• L1 = 1575.42 MHz (Civil + Military)
• L2 = 12276.6 MHz (Military Only)
ICAO international civil aviation organisation, the governing body controls civil aviation in whole world .
headquarters in Montréal, Canada, total 195 countries in the world, 193 are members of ICAO.
Its function is to develop international air navigation and ensure safe growth of ICAO international civil aviation organisation .
There are seven regional ICAO offices in India. DGCA represents ICAO office of Southeast Asia region is located in Bangkok. India is part of that region.
DGCA directorate general of civil aviation .
director general of civil aviation is Vikram Dev Dutt .
location is in New Delhi .
function. Its function is to implement the rules of ICAO and control the civil aviation and India.
ITU international telecommunication union. It comes under UNO .
headquarter is in Geneva, Switzerland, total members 193. It was established in 1934. India signed contract with ITU in 1982 at Narobi. Effective first Jan 1984 representative of ITU in India is WPC
WPC .
wireless planning and coordination Wing.
it comes under Ministry of communication .
established in 1952.
headquarter Sanchar Bhavan, New Delhi .
function. It is responsible for promoting the objective of ITU in India. WPC implement policies framed by ITU in India and regulates communication in India.
also responsible for holding the exam of RTR A radiotelephony restricted for aeromobile and GMDSS, global Maritime Distress and safety services, it provide COP certificate of proficiency for RTR exam issued by WPC .
after getting my COP I will submit to DGCA and DGCA will provide me FREE TOL flight radiotelephony operation License
IATA, international air transport Association headquarters in Canada. It’s function is to represent Lead and serve the airline industry members are 320 airlines in 120 countries.
Inter airline cooperation and to promote safe, reliable and secure, economical air services.
Why do we need RTR in India unlike some other countries in India, WPC is a part of ITU and ITU RR 1990, here means radio regulation states that we have to give exam of RTR
What is communication ?
In aviation exchange of information, messages or signals by means of speaking, writing, pointing.
Speaking
in aviation in India, the very primary means of communication is voice Communication can be Said as speaking, for example, the communication we do on radio with ATC.
Writing
In aviation, this means conduction communication by binary or digitally to perform this, we have a device called CPDLC controller pilot data Link communication, which is also part of FMS Flight management system or FMC flight management computer
CP DLC communicates through satellite known as SATCOM
In in this communication, both aircraft and ATC should be equipped with CPD LC device, then only writing communication as possible
How does CP DLC work ?
when ATC sends message to aircraft with the help of SATCOM, a message with beep sound comes on aircraft. This keeps on beeping till the pilot opens it up when the pilot opens the message. Same time it receives a beep sound which confirms ATC that pilot has seen the message
drawback.
CP DLC is only between aircraft and ATC. Two aircraft cannot communicate with each other controller pilot data link communication.
Pointing
This means of communication is also used when speaking and writing method fails or in radio communication failure, marshallers on ground, use, pointing communication communication
In air, if aircraft is in vicinity of aerodrome with radio communication failure, the ATC uses light gun signals as pointing communication
If aircraft rocks, the wing switch on off, landing lights display displaying navigation light, then aircraft is using finding communication to draw attention of ATC
Radio communication
Communication done by the means of radio waves is known as radio communication
Telecommunication
Any distant communication Is the communication by means of radio waves, optical fibres, broadband cables.
In aviation, we have four types of communication which comes under aeromobile, which are as follows:
AMS aeronautical mobile services, example aircraft
AFS aeronautical fixed service example ATC
ABS aeronautical broadcast service, example ATIS automated terminal information service.
In aviation, we have four types of communication which comes under automobile, which are as follows
Emergency frequencies
Inter pilot 123.45 MHz on VHF
Inter pilot 3023 KHz on HF
ATIS or DATIS standard frequency 123.4
SELCAL(auto alarm)
ATC Inputs SELCAL code of aircraft in encoding device and in cockpit decoding device an alert will be received in the form of Chime sound and lights.
4 letter in 2 pairs in ascending order A to S (excluding I O N)
In India Only on HF (3000 to 4000 nautical miles)
SELCAL 32
16 + 7 + 9
(A to S) + (T to Z) + (1 to 9)
Primary controls of aircraft
Ailerons: Roll left right
Elevators:
Signs on ground
V need assistance
X need medical
Y yes
N no
Search and rescue
DGCA will look for black box (orange in colour in tail area)
CVR (Cockpit voice recorder) 2 hrs recording
FDR (flight data recorder) 25 hrs recording
AFTN
Aeronautical fixed telecommunication network- ATC to ATC communication SENDS MESSAGES OF AIRCRAFT AS PER PRIORITY
Distress code SS
Urgency code DD
No code for direction finding.
Flight safety messages including routine calls -FF
NOTAM or MET messages GG
Flight regulatory messages KK
Aeronautical information service (AIS)
A service established within the defined area of coverage responsible for the provision of aeronautical information/data necessary for the safety, regularity and efficiency of air navigation.
The objective of AIS is to ensure the flow of information/data necessary for the safety, regularity and efficiency of international air navigation.
is a service established in support of international civil aviation, whose objective is to ensure the flow of information necessary for the safety, regularity, and efficiency of international air navigation.
Aeronautical Information Publications (AIPs)
AIPs normally have three parts -
GEN (general), ENR (enroute) - VOLUME 1
and AD (aerodromes). - VOLUME 2
Emergency frequencies
Inter pilot 123.45 MHz on VHF
Inter pilot 3023 KHz on HF
ATIS or DATIS standard frequency 123.4
SELCAL(auto alarm)
ATC Inputs SELCAL code of aircraft in encoding device and in cockpit decoding device an alert will be received in the form of Chime sound and lights.
4 letter in 2 pairs in ascending order A to S (excluding I O N)
In India Only on HF (3000 to 4000 nautical miles)
SELCAL 32
16 + 7 + 9
(A to S) + (T to Z) + (1 to 9)
Primary controls of aircraft
Ailerons: Roll left right
Elevators:
Signs on ground
V need assistance
X need medical
Y yes
N no
Search and rescue
DGCA will look for black box (orange in colour in tail area)
CVR (Cockpit voice recorder) 2 hrs recording
FDR (flight data recorder) 25 hrs recording
PLN flight plan to main reasons to file a flat plan, search and rescue SAR and AFTN air traffic flow management.
PLN flight plan, the estimated flight plan we make on ground is PLN . FPL file flight plan when we file our PLN, it becomes FPL. CPL current flight plan. If you make any changes to our FPL due to technical issues, route navigation, et cetera, it becomes new current flight plan CPL. This is the actual flight plan on which we will be flying in air. If everything goes as we have filed, then FPL equals to CPL.
How to submit PLN different ways of submitting BLNR online official website of AAI airport authority of India , A TC Tower on ground, to FIC flight information, Center directly, submit, hardcopy, or scan or fax, directly to current ATC.
Who is responsible for PLN activities? There are 22 nodal officers in India to handle PLN activities
Who can file the PLN?
PIC pilot in command or authorised dispatcher.
What is the validity of PLN ?
validity is always taken keeping reference of EOBT estimate off block time or ETD estimated time of departure .
Filing time, maximum 120 hours or five days prior before EOB T minimum three hours before E OBT estimated of block time .
Where is entry of DOF date of flying ?
in PLN in box number 18, other info if date of filing and date of flying is different if we don’t put any thing about DOF inbox number 18 at automatically means date of flying and date of filing is same .
Note :
after filing flight plan, we will get FIC number and ADC number air defence clearance. Every time I file PLN, it will go to FIC flight information centre FIC, send information to MLU movement licensing unit. MLU monitor the movement and gives the ADC number, which is our permission to take off .
Any restricted or prohibited or danger area will be notified by red colour boundary on charts .
Danger area
For example, VAD41, this is danger area in Bombay FIR of sequence 41 area of military operation operations example artillery firing aircraft does not require any permission but have to exercise caution .
Restricted area
for example VIR31, this is restricted area in Delhi FIR of sequence 31. We cannot enter in restricted area without permission to ways to fly in restricted area. First take permission from ATC second limitation to fly inside given by ATC.
Prohibited area
For example, VOP12, this is prohibited area in Chennai FR of sequence 12. We cannot enter in these areas in any circumstances if by mistake I enter in this area, they don’t descend and Land to the nearest suitable airport. .
Prohibited areas in India, one, the Rashtrapati Bhavan in India to Parliament building PM residence three, Tirumala Venkateswara Temple in Tirupati, four Padmanabha Swamy Temple in Thiruvananthapuram Kerala 5D Taj Mahal, Agra, six tower of silence, Mumbai, seven refinery eight Baba atomic research centre nine, Golden Temple Amritsar, 1010 km radius of over Kalpakkam nuclear installation, Tamil Nadu .
Uncontrolled areas
Area which is not in first dotted circle that is to the second dotted circle and also not in control boundaries are uncontrolled areas .
If I am an uncontrolled area, whom should I contact?
according to priority,
first FIS or defence control.
Second look overhead here, I have control
Third, if nothing is overhead next en route, ATC .
Rules for pushback
Before pushback and start-up, check for all person on board, POB must be carried out. The aerobridge or stepladder must be removed before start-up. All the doors of the aircraft must be closed .
format.
obtain pushback, obtain start-up, obtain pushback, and start-up .
if DATIS is available, then use information a else use weather obtained.
Taxi
After start-up, we do Taxi
Format
Stand 02, request Taxi information bravo .
Rule for Taxi
If you want to use full length runway, notify ATC prior to commencement of Taxi .
Departure or takeoff.
Takeoff when on runway, we use power and release break from takeoff role and after taking off till aircraft reaches 1500 feet .
VFR visual flight rule
All the thousand levels are of IFR, even VFR can fly on thousands, but priority will be given to IFR all the thousands +500 levels are only for VFR
That’s why it’s called exclusive VFR levels, minimum altitude for flying to altitude 2000 feet minimum flight level for flying flight level 50 maximum flight level for flying flight level 460
Position report .
on reaching designated points, we have compulsory reporting points .
CVSM conventional vertical Separation minima till FL280 1000 feet Separation from reciprocal traffic.
From F2 90 2000 feet Separation from reciprocal traffic.
RVSM reduced vertical Separation minima.
FL290- FL410 . But for safety, I decided to put list of equipments to be carried on board.
ICAO decided to put levels between CVSM levels FL290 - FL410 .
List of equipments to be on board for RVSM :
1. Mode C/S transponder ,
2. TCAS 2/ICAS 2 ( TA traffic advisory plus RA resolution advisory) traffic collision avoidance system, or airborne collision avoidance system.
3. Altitude and coding device/altimetry system.
Two altimeter with independent static source, if reading of the different between both altimeter increases by 200 feet or more, that means either of the altimeter is clagged or blocked or not working .
4. Altitude holding device in autopilot .
5. Altitude alerting device, if you set any altitude and your altitude changes, it starts beeping .
Phrases for descent in RVSM:
Unable RVSM due equipment
Unable RVSM due turbulence.
Ready to resume, RVSM ( if equipment fixed )
RVSM equipment contingency procedure.
If no ATC in contact and mood C/S failed transponder
In this, we go to plus -500 feet
Deviate to the side, where there is less congestion of ATC route .
RCF radio communication failure. When the station of your interest is not responding. We consider the station under radio communication failure. Technically RCF is due to receiver failure. For example, we consider receiver, failure or transmitter failure or both failed.
RCF, due to human error, wrong election of frequency volume mute watch our circuit breakers
AIP aeronautical information publication
What else can I do? Try to establish communication through other aircraft if available?
Delhi control not responding, then contact next en route ATC .
Then that ATC will contact your Delhi control on ATN, aeronautical, fixed telecommunication network and will relay the message that he receives .
If then also, you experience radio communication failure
En route Land to nearest aerodrome ASAP .
RCF in IMC
Ground follow your last cleared limit, then wait for ATC to contact you, but he or she will not get any response and will send follow me vehicle to your last cleared limit and that vehicle will make you follow him to the apron.
You just took off every airport has radio communication for failure. Procedure followed, and Land.
If you are en route, follow your flight plan, last cleared limit will be your destination. Fly last assigned speed and level for seven minutes radar for 20 minute non-radar.
MEL minimum en route level:
If you received clearance was flight level 00, you need to climb to flight level 120MEL and then cruise for seven minutes environment and then climb to your FPL altitude and resume normal navigation. RNN always compare your assigned altitude with your MEL given and fly the highest for seven or 20 minutes above rule is only applicable when you clear level is other than flight plan level and also it is applicable during climbing only while radio communication failure.
ILS instrument landing system
Different types of approaches:
1. Precision approach ILS. Lateral plus vertical guidance lateral is left and right vertical is up and down.
Non-precision approach, lateral guidance, VOR and NDB.
Distress/emergency
When you need immediate attention may may may if you transmit this. There will be in position of silence. All other station stops transmitting conditions for Distress engine failure if losing height aircraft out of control aircraft on fire or smoke, sudden decompression above FL100 hijack intention, unsure of plan and you have to fly flight level plus -500 feet. Entered probed area by mistake, pilot in capacitance, make emergency landing at nearest suitable airport, Hydraulic failure, force, lending straight, add major structural damage due to any reason, fuel leakage with risk of fire. Enter CB cumulonimbus cloud, primary controls affected, electrons, elevators radar. Entered spin .
Urgency
Need assistance, but not immediate
Pan pan pan pan pan pan
Conditions
If any Distress situation sighted secondary controls failure flap, slats, sick passenger or passenger bleeding in flight, severe turbulence at any level hot tire or hot break indication plus loud noise. If only hot tire, then stop the aircraft slowly and request firefighting services for visual check, FFS. hydraulic pressure low, any UFO and identified flying object, sighted.
Security
Security security security
Condition
Any natural calamity in sight, but not affecting route of flight for example, volcanic activity, tsunami, forest fire, severe cyclone, locust, invasion.
Air prox
Proximity in air, if in air, any other aircraft comes nearby, we call it air prox or any incident in air. Due to other aircraft is called air prox. If on ground, it is called incident.
In air air prox
Air prox risk of collision
If other aircraft crosses you by five nautical miles or less very closely dangerously close.
Air prox safety, not assured
The lateral separation between aircraft required is 15° at 15 nautical miles aircraft, not maintaining required separation minima.
Air prox, no risk of collision,
Given by ATC
air prox risk, not determined.
If someone nearby you, but not determined.
Incident ground incident reporting
You are on taxiway alpha and aircraft crosses you on intersection, P1 very closely
Wind shear
Sudden change in wind, speed, and or direction over a short distance, if you are informed about Wind shear activity on ground, cancel your departure if I am on finals, landing is difficult initiating go around GA.
PREP pilot report AIREP air report
It is pilot report given by pilot to ATC about any unforced weather change
Microburst
It is very intense down droughts, which is dangerous while takeoff and landing
Seek necessary permission, 10 minutes prior .
Radio waves or electromagnetic waves
It consists of two components, electric and magnetic both are perpendicular to each other
Polarisation of radio waves, it depends on electrical component vertically, polarised electrical component and vertical plane magnetic component in horizontal plane
Horizontal polarised electrical component and horizontal plane magnetic component in political plane. Receiving antenna and electrical component are of radio waves are placed parallel to each other
frequency. Number of cycles passing through a point per second unit is hertz.
Wavelength distance covered by one complete cycle or distance between two trucks or distance between two crests
Phase position of radio wave in a cycle unit is degrees
Amplitude, maximum displacement from main position frequency is equals to speed of light in metre per second divided by wavelength in metres
Modulation process of super imposing frequency on carrier wave
types of modulation
Frequency modulation frequency of carrier waves varied in accordance to frequency of audio signal, keeping the amplitude constant frequency is very amplitude is constant
Amplitude modulation amplitude of the carrier wave is varied in accordance to the amplitude of audio wave, keeping the frequency constant amplitude is very frequency is constant
Phase modulation phase of carrier wave is varied after fixed interval used in GPS
Properties of radio waves, travel with speed of light 3×10 power 8 m/s
When travels from denser to rare medium, it will accelerate and bends away from normal and vice versa
Radio wave gets refracted, reflected refracted and attitude during propagation while travelling
Radio wave follows greater circle path, or GC path
Propagation of radio waves, propagation of radio waves depends on the way the receiver is receiving the signal types of propagation, ground wave propagation and skyway propagation surface ground wave propagation consist of surface waves plus space waves in space wave. There are two direct wave and ground reflected wave.
Ground waves all the waves other than sky waves
Sky wave is a wave received by receiver after getting reflected from ionosphere
Groundwave
Surface wave
Radio wave travelling with the help of ground
Range depends upon power of transmission ranges equals to 3 under root power at C range equals to 2 under root power on land wavelength is directly proportional to range ranges directly to wavelength. Range is maximum on C because there is less at attenuation or absorption.
Space radio wave direct from transmitter to receiver. It follows line of side. Propagation ranges, directly proportional to height of transmitter ranges directly proportion to height of receiver are equals to 1.25 under root height of transmitter +1.25 under root height of receiver in feet.
Sky wave 3 to 30 MHz
HF frequency radio wave refracted from ionosphere DEFR layers of ionosphere Dealer disappears at night, increasing height of Innosphere Innosphere consist of charged atoms. The density of sphere depends upon intensity of charge, and these are charged by UV rays. More UV rays, more ionisation you are maximum when sun is overhead zing meridian and in summer.
Factors affecting sky waves, ionisation layer, density change in frequency, height of ionisation layer,
skip distance
Distance between transmitter and a point where first skywave return is received
Dead space or skip Zone
Distance between end of round wave and the point where first skywave return is received
Critical Ray
First sky wave returned
Critical frequency
Frequency at which critical ray is received
Critical angle
Angle of incidence at which critical ray is received
Refraction
Bending of radio signals
Feeding
Variation and radio signal or sudden increase or decrease in signal strength
Attenuation
Weakening or absorption of signal
Types of attenuation

Ground attenuation more on land, then see
Atmospheric at innovation mostly in high frequency band, primarily due to water vapour in atmosphere frequency is directly proportional to atmospheric attenuation
Ionosphere attenuation due to ions and atmosphere frequency is inversely proportional to atmospheric attenuation
VLF 3 to 30 kHz LF 30 to 300 kHz, gets absorbed by spheric layers. Part of MF and HF are reflected back VHF and above passes through the layer.
VLF 330 kg hertz LF 30 to 300 kg hertz MF 300 kg hertz to 3 MHz, HF 3 to 30 MHz VHF 32 300 MHz
Full forms
LUT, local use terminal. Active Bangalore standby Lucknow.
ISRO in Bangalore manages on Satellite
INMCC Indian mission control centre Bangalore
RCC rescue coordination Centre
AIS aeronautical information services
XRDL crossing radial
ETO estimated time over nest significant reporting point
SAR search and rescue
IAF RH Indian Air Force rescue helicopter
ETO estimated time over next significant reporting point
VFR visual flight rule
MAP aeronautical charts publish.
QNH aerodrome level pressure reduced to means sea level pressure.
QFE actual pressure at aerodrome . Also called height.
AGL above ground level
QNE Standard pressure setting or flight level . Runway elevation or elevation.
Threshold TWD, beginning part of runway used for landing .
ARP aerodrome reference point .
ATS air traffic services
FIS flight information service
ATC air traffic control
SMC surface movement controller
TWR tower
APP approach
ACC area control centre
ATIS: automated terminal information service .
VATIS voice automated terminal information service
DATIS datalink or digitally, automated terminal information service
Danger area restricted area prohibited area.
S/U start-up
PB pushback
T/O take off
FFS fire fighting services
VHF, very high frequency
RNAV radio navigation
NDB nondirectional beacon
VOR, very high frequency omni directional range
CVSM conventional vertical Separation minima
RVSM reduced vertical separation minimum from flight level 290 to flight level 410
SCR semi circular route
RCF radio communication failure
AIP aeronautical information publication
AFTN aeronautical fixed telecommunication network
MEL minimum en route level
TA traffic advisory
RA resolution advisory
ETA estimated time of arrival
EAT expected approach time
ILS instrument landing system
TEET total estimated Elapsed time
DME distance measuring equipment
VCNT vicinity
AP Air prox proximity in air
WS wind sheer
PIREP pilot report
AIREP air report,
MB microburst
TS thunderstorm
DD down droughts
A Altitude
AiS aeronautical information services
AIS has
:
NOTAM notice to air man
AIP aeronautical information publication
AIRAC, aeronautical information, regulation and control
PIB Pre-flight information bulletin
AIC aeronautical information circular issued by DGCA, all others are in issued by AAI
NOTAM, any changes in aeronautical serviceability affecting aircraft operation in general, it is for short or long duration, but short notice which does not include extensive text or graphics will come under NOTAM.
Class one issued in quad form issued by and delivered on AFTN for immediate disposal
Class two issue in form of text messages issued in large text and sent via mail, not for immediate disposal
Series a any changes in aeronautical serviceability affecting aircraft operation for more than two hours. Also delivered internationally to countries having flight time less than two hours.
Series B. Any changes in aeronautical serviceability affecting aircraft operation operations for more than 30 minutes but less than two hours also delivered internationally to countries having flight time less than two hours
Series C any changes in aeronautical serviceability affecting aircraft operations and only domestic airport delivery is domestic
Series D any changes in aeronautical serviceability affecting aircraft operations of defence air fields, which are utilised by civil operators
Series G for any changes of lasting character that includes general aviation, and if two or more FIIs are going to be affected by any changes
NOF international NOTAM Office
Series G NOTAM has always issued by NOTAM Office New Delhi
SELCAL selective calling
SAR search and rescue
SASAR satellite aided search and rescue
COSPAS name of Satellite, edited search and rescue programme
ELT emergency locator transmitter
ELBA emergency locator transmitter beacon
EPIRB emergency position indicator radio Beacon
PLB Personal locator Beacon
CVR cockpit voice recorder last for two hours
FDR flight data recorder last for 25 hours
Ailerons roll left right
Elevators pitch up or down
Rudder yaw left or right
Flaps and slats
RVSM approved
Approved non-RVSM RVSM non-compliant aircraft, any equipment failurebelow flight level290 and we are permitted to go to RVSM level
Non RVSM approved if we are in RVSM level and we get any instrument failure, and if ATC will tell us to stay in RVSM, then we will be in this category.
SARPS Standard and recommended practice is also called annexure.
PANS procedure for air navigation services,
PANS ATM procedure for air navigation, services, air traffic management .
SUPPS regional supplementary procedures
Civil evasion Minister, KRM Naidu .
DGCA functions :
License pilot/AME,
aircraft regulation,
aircraft accident, or incident investigation,
coordination with ICAO
RDARA regional and domestic air route area
MWARA major world air route areas
MID middle east 2
SEA Southeast Asia 1
INO Indian Ocean 1
INCERFA uncertainty phase
ALERFA alert phase
DETRESFA Distress phase
VOLMET, it’s a routine voice broadcast of weather information for aircraft in flight
SIGMET significant meteorological information, it’s a severe weather advisory
METAR format for reporting whether meteorological aerodrome report
VHF 30 to 300 MHz
VDF, very high frequency direction frequency is 118 to 136 MHz
ADF frequency 190 kHz to 1750 kHz
NDB frequency 190 kHz to 450 kHz
ADF automatic direction finding frequency is 190 kHz to 1750 kHz
VOR, very high frequency omnidirectional range
Frequency 108 MHz to 117 decimal 95 MHz
ILS instrument landing system . Frequency 108 MHz to 112 MHz odd.
Glidescope
Frequency 328 MHz to 335 MHz UHF .
Radio altimeter frequency is 4200 MHz to 4400 MHz .
Airborne weather radar
frequency 9375 MHz or 10 MHz. SHF .
SSR secondary surveillance radar .
frequency of interrogation signal, 1030 MHz on ground.
transponder signal 1090 MHz on aircraft
TCAS traffic avoidance system by USA .
ACAS airborne collision avoidance system by ICAO
DME distance measuring equipment frequency 962 MHz to 1213 MHz UHF .
In DME aircraft interrogator ground transponder .
GPS global positioning system .
GNSS global navigation satellite system .
GAGAN GPS aided geo augmented system.
L1 band frequency 1575 decimal 42 MHz . UHF decimetric used by civilians. Accuracy is 30 m, but deliberately degraded to 100 m.
L2 band frequency 1227 decimal 6 MHz . UHF decimetric . It is encrypted. Accuracy is 1 to 3 m.
Control
One master Station based at Colorado, USA, other stations at different places on earth .
User
When receiver is switched on, it searches for signal on correct frequency .
Annexure one - Personal licensing .
annexure two - rules of the air .
annexure, seven - aircraft, nationality, and registration marks .
Annexure eight - air worthiness of aircraft .
Annexure nine facilitation .
annexure 10 aeronautical telecommunication .
annexure 11 air traffic services .
Annexure 12 search and rescue .
Annexure 13 aircraft accident and incident investigation .
Annexure 14 aerodromes .
annexure 15 aeronautical information services.
annexure 18 the safe transportation of dangerous goods by air .
Frequencies
VHF 30 to 300 MHz
VDF, very high frequency direction frequency is 118 to 136 MHz
Required Equipment, VHFRT radio telephony
Uses homing ,checking trek, let’s down
Propagation, A3E
NDB nondirectional beacon.
NDB has two components :
ADF automatic direction finding in aircraft receiver,
NDB on ground transmitter.
ADF frequency 190 kHz to 1750 kHz
NDB frequency 190 kHz to 450 kHz
Range day, 200 nautical miles night, 70 nautical miles .
Accuracy plus -5° beyond 70 nautical miles
ADF automatic direction finding frequency is 190 kHz to 1750 kHz
Principal bearing by loop theory
Propagation surface wave
ADF has two antenna.
Sense antenna, omnidirectional antenna receive signals from all directions. Polar diagram is circle.
Loop antenna has directional property because of rotation we get 2 minima and 2 Maxima in one rotation. Called 180° ambiguity. Polar diagram is figure of eight.
To resolve this 180° ambiguity, we combine the reception of loop and sense antenna. Polar diagram is called cardioid.
Accuracy is plus -5°.
VOR, very high frequency omnidirectional range
Frequency 108 MHz to 117 decimal 95 MHz
Between 108 MHz to 112 MHz frequency shared by ILS localiser .
all odd first decimal localiser .
all even first decimal VOR.
112 MHz to 117 decimal 95 MHz is exclusively for VOR .
accuracy is plus -5° .
total VOR channels are 160.
emission code is A9W .
Polarisation is horizontal .
propagation is line of SIGHT.
Working principle is working by phase Comparison.
Polar diagram is limacon.
Total VOR channels are 160
ILS instrument landing system .
emission code A8W, .
different type of approaches,
precision approach, lateral plus vertical guidance,
non-precision approach, lateral guidance
Localiser gives lateral guidance, glide scope gives vertical guidance.
Frequency 108 MHz to 112 MHz odd.
Provides horizontal guidance along the extended runway central line .
Principal bearing by lobe comparison
Coverage of localiser plus -10° of central line till 25 nautical miles .
plus -35° of central line till 17 nautical miles .
full scale deflection of localiser equals to 2.5° .
Glidescope
Frequency 328 MHz to 335 MHz UHF .
Provides vertical guidance on approach path .
Principal bearing by lobe comparison .
Coverage of Glidescope: 0.45 glide slope angle to 1.75 glide slope angle.
AzimUth coverage, 8° left or right from centre line till 10 nautical miles.
Outer marker, blue .
middle marker Amber .
inner marker white.
Radar radio detection and ranging. Uses VHF and above frequency bands propagation line of site.
Use pulse technique
VHF and above frequencies are free from external noise. Static interference and side-effect. Higher frequency means shorter wavelength, which provides narrower beams. Detect small targets, shorter pulses, .
Radar travels with the speed of light in microseconds 300 m/µs.
Pulse.
Each pulse has a lot of cycles pulse with distance between start-up pulse and end up pulse.
PRP pulse recurrence period. PRI pulse recurrence interval time interval between start-up pulse to next start-up. Pulse unit is microseconds.
PRF pulse recurrence frequency or PRR pulse recurrence rate . number of pulse per second .
unit PPS pulse per second .
Factors affecting range of radar, transmission power, height of radar head . terrain, wavelength, and attenuation by raindrops .
Primary radar works on echo principle. Secondary radar works on secondary radar. Principal.
Primary radar, transmitter and receiver frequencies. Same in secondary radar. Transmitter and receiver frequencies different.
primary radar, transmit, single pulse, secondary radar, transmit pair, of pulses.
Primary require more power. Secondary required less power.
Primary has less range. Secondary has more range .
instruments of primary radio altimeter, airborne weather radar, ASMI. secondary radar instruments are DME, SSR, TCAS, GPS.
Primary radar provides direction and distance of target. Secondary radar provides additional information like aircraft, call, sign, altitude, speed, and destination .
Primary radar is affected by Weather. Secondary radar is not affected by Weather.
Radio altimeter frequency is 4200 MHz to 4400 MHz .
Range 2500 feet .
Working FM frequency, modulated continuous wave transmission .
Works on echo principal and transmit continuous wave vertically below the aircraft .
Accuracy is plus -3% +5 feet above 500 feet .
It gives mushing error . the closer the aircraft to the ground, then transmitter antenna, reflection point and receiver antenna forms a triangle.
Airborne weather radar.
Principal is primary radar. Principal
frequency 9375 MHz or 10 MHz. SHF .
wavelength centimetric.
GPS global positioning system .
GNSS global navigation satellite system .
GAGAN GPS aided geo augmented system.
GPS is divided into three segments;
First space, second control, third user
Space :
it has 24 satellites 21 active three standby.
They all are rotating and six circular orbits. Each orbit has four satellites. Each satellite has four atomic clocks. Combination of orbit with satellite is an NAVSTAR. Each orbit inclined at 55° to equator at height of 20180 km. Each satellite completes one revolution and 12 hours.
The satellites are transmitter on two different bands, L1, and L2 .
L1 band frequency 1575 decimal 42 MHz . UHF decimetric used by civilians. Accuracy is 30 m, but deliberately degraded to 100 m.
L2 band frequency 1227 decimal 6 MHz . UHF decimetric . It is encrypted. Accuracy is 1 to 3 m.
SSR secondary surveillance radar .
frequency of interrogation signal, 1030 MHz on ground.
transponder signal 1090 MHz on aircraft
TCAS traffic avoidance system by USA .
ACAS airborne collision avoidance system by ICAO
DME distance measuring equipment frequency 962 MHz to 1213 MHz UHF .
In DME aircraft interrogator ground transponder .
For radio, check,
How do you read? Read you five. Read you five: call sign.
Four time check
Request time check 0500 . Time now 0500. Time now, 0500 call sign.
Without using numerals time, request time check,
Request time, check on the hour. Confirm time in GMT. Affirmative.
Push back and start up
Stand one zero security check carried out person on board 130.
Request push back and start up .
information B (if DATIS is available), weather obtained (if DATIS is not available)
Taxi
Transmit Stand 02 request taxi information B.
Receiver, Taxi via E, B, F hold short runway, 09
Transmit taxi via E, B, F hold shot runway, 09 call sign
Departure or takeoff
Cancel departure, destination, airport closed, or FFS not available
Transmit on taxiway B
Cancel departure due destination, airport closure
Request taxi back to apron.
Transmit on taxiway B
Cancelled departure due FFS not available.
Request, taxi back to apron.
You are taxiway, see approaching hold short runway 09
Transmit approaching hold shot runway 09 on taxiway C
request lineup runway 09
Receiver clear lineup, runway 09
Transmit, clear line up runway 09 call sign
You are lined up runway 09
Transmit land up runway 09
request departure .
Receiver, clear takeoff runway 09
Transmit, clear, takeoff runway, 09: call sign
Sighted birds on runway 09
Transmit on takeoff role runway 09
Cancelling takeoff due birds on runway
Sighted birds on takeoff path
Transmit on takeoff path runway 09 passing altitude, 1000 feet, deviating 15°, right due birds on takeoff path
Approaching hold shot runway, 09 ask departure without stopping
Transmit on taxiway C
approaching hot shot runway, 09
request, expeditious departure .
Receiver, hold shot runway 09
Transmit: hold shot runway 09
call sign
Position report, PTRF
Frequencies
Emergency frequencies
Inter pilot 123.45 MHz on VHF
Inter pilot 3023 KHz on HF
ATIS or DATIS standard frequency 123.4
VHF Emergency frequency
121.5 MHz, 123.1 MHz, 243 MHz
VHF 30 to 300 MHz
VDF, very high frequency direction frequency is 118 to 136 MHz
NDB nondirectional beacon.
NDB has two components :
NDB frequency 190 kHz to 450 kHz .
ADF automatic direction finding frequency is 190 kHz to 1750 kHz
VOR, very high frequency omnidirectional range.
Frequency 108 MHz to 117 . 95 MHz .
Between 108 MHz to 112 MHz frequency shared by ILS localiser .
all odd first decimal localiser .
all even first decimal VOR.
112 MHz to 117 . 95 MHz is exclusively for VOR .
emission code is A9W .
Polarisation is horizontal .
propagation is line of SIGHT.
Total VOR channels are 160
ILS instrument landing system .
emission code A8W, .
Localiser Frequency 108 MHz to 112 MHz odd.
Glidescope
Frequency 328 MHz to 335 MHz UHF .
Provides vertical guidance on approach path .
Radio altimeter frequency is 4200 MHz to 4400 MHz .
Airborne weather radar.
Principal is primary radar Principal.
frequency 9375 MHz or 10 MHz. SHF .
wavelength centimetric.
GPS global positioning system .
different bands, L1, and L2 .
L1 band frequency 1575 . 42 MHz . UHF decimetric.
L2 band frequency 1227 . 6 MHz . UHF decimetric .
SSR secondary surveillance radar .
frequency of interrogation signal, 1030 MHz on ground.
transponder signal 1090 MHz on aircraft
TCAS traffic avoidance system by USA .
ACAS airborne collision avoidance system by ICAO
DME distance measuring equipment frequency 962 MHz to 1213 MHz UHF .
In DME aircraft interrogator ground transponder .
- VOR (VHF Omnidirectional Range): A type of short-range radio navigation system for aircraft, allowing them to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons.
- Doppler VOR: An advanced type of VOR that uses Doppler shift principles to provide more accurate bearing information, particularly effective in reducing errors caused by ground reflections.
-
NDB-ADF (Non-Directional Beacon and Automatic Direction Finder):
- NDB: A non-directional radio beacon that transmits signals in all directions, which aircraft can receive and use to determine their bearing relative to the beacon.
- ADF: The Automatic Direction Finder is the aircraft equipment that receives NDB signals and displays the direction to the NDB station relative to the aircraft’s heading.
- DME (Distance Measuring Equipment): A transponder-based radio navigation technology that measures the slant range (line-of-sight distance) between an aircraft and a ground station.
- AFTN (Aeronautical Fixed Telecommunications Network): A worldwide system of aeronautical fixed circuits providing data exchange between civil aviation authorities, air traffic services, and other entities involved in aviation operations.
-
MWARA (Major World Air Route Area) and RADARA (Regional and Domestic Air Route Area):
- MWARA: A designated area over major international air routes where specific communication protocols and frequencies are used.
- RADARA: Similar to MWARA, but pertains to regional and domestic routes, often using different communication procedures suited to these areas.
-
Difference Between HF and VHF:
- HF (High Frequency): Ranges from 3 MHz to 30 MHz, with long-range communication capability due to its ability to reflect off the ionosphere (skywave propagation).
- VHF (Very High Frequency): Ranges from 30 MHz to 300 MHz, used for short-range communication as VHF signals travel in a straight line and are generally limited to line-of-sight.
-
Why VHF is Used in Communication:
- VHF is preferred in aviation communication because it provides clear and reliable voice communication within line-of-sight, has less atmospheric interference compared to HF, and is suitable for the short distances involved in most air traffic communication.
-
Range of VHF and HF Frequency:
- VHF: Effective range is typically 100-200 nautical miles (NM) depending on altitude and antenna height.
- HF: Can be thousands of miles, depending on atmospheric conditions, as it can reflect off the ionosphere.
-
Bandwidth:
- VHF Communication Bandwidth: Typically around 25 kHz or 8.33 kHz in regions where frequencies are more tightly spaced.
- HF Communication Bandwidth: Varies depending on the application but is generally broader due to the need for long-distance communication.
-
Single Side Band (SSB) vs. Double Side Band (DSB):
- SSB: A type of amplitude modulation that uses only one sideband, reducing bandwidth and improving power efficiency.
- DSB: Amplitude modulation that includes both the upper and lower sidebands, leading to greater bandwidth usage compared to SSB.
-
Spacing Between Two VHF Frequencies:
- Typically, 25 kHz, but in regions with crowded airspace, it can be reduced to 8.33 kHz to allow more channels within the same frequency range.
PART 2:
- NDB (Non-Directional Beacon): A radio transmitter at a known location, used as an aviation or marine navigational aid. NDB signals follow the curvature of the Earth, so they can be received at low altitudes and over long distances.
- CPDLC (Controller-Pilot Data Link Communications): A method of communication between an aircraft and air traffic control using data link messages instead of voice communication.
- Distress Call: The international radio distress signal is “Mayday,” used in life-threatening emergencies.
-
Frequency of CPDLC & NDB:
- CPDLC typically operates over VHF (Very High Frequency) and SATCOM (Satellite Communication) depending on the region and specific system.
- NDBs operate in the LF (Low Frequency) and MF (Medium Frequency) bands, typically between 190 kHz and 535 kHz.
- ILS (Instrument Landing System): A precision runway approach aid based on two radio beams which together provide pilots with both vertical and horizontal guidance during an approach to land.
- Flying Expy: This seems unclear. It might refer to an abbreviation or a specific term in aviation, but more context is needed.
- No. of Attempts: This likely refers to the number of attempts allowed for a specific task, such as a landing approach or exam retries. The context would clarify.
- TORA (Takeoff Run Available): The length of runway declared available and suitable for the ground run of an airplane taking off.
- TODA (Takeoff Distance Available): The length of the takeoff run available plus the length of any clearway.
-
Runway and Stopway Difference:
- A Runway is a defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft.
- A Stopway is an area beyond the takeoff runway, no less wide than the runway, and able to support an aircraft during an aborted takeoff without causing structural damage to the aircraft.
- NOTAM (Notice to Airmen): A notice filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location.
- Runway Lights: These include different types like edge lights, centerline lights, and touchdown zone lights, which guide pilots during landing and takeoff, especially at night or in low visibility.
- Annex 10: Refers to the ICAO (International Civil Aviation Organization) document on Aeronautical Telecommunications, detailing standards and recommended practices for communication, navigation, and surveillance systems.
-
Difference Between Relative Bearing and Radial:
- Relative Bearing: The angle between the direction to an object and the aircraft’s heading.
- Radial: A line of position extending outward from a radio navigation aid (like a VOR), defined by the direction from the station.
- Homing: Refers to the method of navigating toward a radio beacon or other navigational aid by adjusting heading to maintain a relative bearing of zero.
-
Disadvantage of NDB:
- Susceptible to atmospheric disturbances and signal interference.
- Less accurate compared to modern navigation systems like VOR or GPS.
-
Uses of CPDLC:
- Reduces communication errors and radio congestion.
- Provides clear and unambiguous messages.
- Enables efficient communication in areas with poor VHF coverage, such as oceanic regions.
