Navigation Keynotes


NAVIGATION KEY NOTES

Navigation notes for reference

NDB

 
 
NDB 190KHz – 450KHz      
  ADF 190KHz – 1750KHz      
  Freq. Band Upper Low Frequency      
      Lower Middle Frequency      
  Principle Bearing by loop theory      
    Purpose Gives 360 degree bearing        

VOR

           
               
    Purpose   Transmits 360 Magnetic radials        
                 
    Principle   Bearing by phase comparison    
    Frequency   108MHz – 118MHz        
    Freq. band   VHF        
VOT            
             
        In ground   +/- 4 degree        
        Airborne   +/- 6degree        
        Dual VOR   +/- 4degree        
    check            
180 OBS   +/- 4 * deflection To indication
360 OBS   +/- 4* deflection FROM indication

 

ILS

  Azimuth Information   Localizer
       
  Range Information   Marker beacon
  Glide path   Glide Slope

 

LOCALIZER

Purpose   Gives azimuth information (All odd 1st   decimal  
     
Frequency   108MHz – 112MHz
Band   VHF
Principle   Bearing by lobe comparison

 

GLIDESLOPE

Purpose Gives glide slope indication
Frequency 329.3MHz – 335MHz
Band UHF
Principle Bearing by lobe comparison

MARKER BEACON

Outer Marker Blue (– — –) 400Hz 600m 3.5Nm-6Nm
Middle Marker Amber (  .– –) 1300Hz 300m 3500feet
Inner Marker White (. . .)   3000Hz 100m 1050Feet

 

ILS CATAGEORY      
           
Category Decision Height (DH) RVR  
           
I   200feet   550meter  
II   100feet   350meter  
III a   ↓10 0 feet   200meter  
III b   ↓50 feet   50meter  
III c   Zero   Zero  
SECONDARY SURVEILLANCE RADAR

 

Principle Mode & Code Pulse
Frequency 1030MHz – 1090MHz
Band UHF
Purpose Used by ATC for aircraft identification

TRANSPONDER

 

Mode A   8μsec PRP Identification of Aircraft
Mode B   17μSec PRP   Standby for Mode A
       
Mode C   21μSec PRP   Altitude information in steps of 100feet.
       
Mode S       Altitude information (25 feet) and acts as data transponder
         

 

SQUWAK CODE

 

  7500   Unlawful interference        
           
  7600   Communication failure        
           
  7700   Emergency      
  2000   No code allotted      
  0000   Transponder failure        
           
  1200   VFR flight    
             
RADIO ALTIMETER          
Purpose     Measures height of the aircraft    
Frequency     4.2GHz – 4.6GHz    
Wavelength λ     7Cms    
Band     SHF    
                 

 

MLS

 

Principle Time reference scan beam (TRSB)
Frequency 5.03GHz – 5.09GHz
Band SHF
Wavelength λ 6cms

 

DME

 

Principle Random PRF Tech.
Frequency 962MHz – 1213MHz
Freq. Band UHF
Purpose Used to measure slant range.

 

Navigation notes for reference

 

Take off Segments

A normal take off is divided in four segments.

Seg 1:

  • +ve Climb.
  •  Airborne Aircraft from 35ft AGL to Gear up position.

Seg 2 :

  • Gear up position to 400ft
  •  4% climb gradient.

Seg 3 :

  • Acceleration to retract flap & level off.
  •  400ft to Flaps up

Seg 4 :

  • 2% climb gradient with max continues power
  •  Flaps up to power down. ( Cruise setting)

Note:

 

  1. Climb gradient required to be met with 1 Engine inop on
  • 3engine A/C is 7%.
  •  2engine A/C is 4%.
  • 4engine A/C is 3%.

FLIGHT INSTRUMENTS

  • Flight instruments are divided into three different categories. They are
    1. Pitot/ Static instruments (pressure flight inst.)
    2. Gyroscopic instruments
    3. Compass instruments

PITOT STATIC INSTRUMENTS:

  • Airspeed indicator
  •  Altimeter
  •  Vertical speed indicator

GYROSCOPIC INSTRUMENTS:

  • Directional Gyro Indicator (DGI)
  •  Attitude Indicator (AI)
  •  Turn coordinator (TC)

COMPASS INSTRUMENTS:

  • Magnetic compass

 

Navigation notes for reference

PRESSURE FLIGHT INSTRUMENTS

  • Airspeed indicator.
  •  Vertical speed indicator.

Pressure instruments measure atmospheric pressure by using the pitot – static system, which is a combined sensor system that detects the following

  1. Total pressure (Pitot pressure) = Static + Dynamic [measured by Pitot tube]
  2. Static pressure [ measured by static port in a pitot tube or by a separate static vent ]

Difference between both gives the Dynamic pressure.

Dynamic pressure = Total pressure – Static pressure.

Dynamic pressure = (½ R) * (V2)

Dynamic pressure: pressure of air molecules impacting into surface, caused either by movement of body or by airflow.

AIR SPEED INDICATOR (ASI)

Navigation Keynotes

Air Speed Indicator Gauge Indications

 

 

 

 

 

 

 

 

 

 

 

 

PRINCIPLE:

  • The ASI measures the dynamic pressure as the difference between total pitot pressure and the static pressure.

Air speed (Dynamic) = Total Pitot – Static pressure

Principle Difference between Total Px & Static Px
Errors BLIPDC
Tolerance +/- 3 Kts
Function Pitot/ Static

Altimeter

Navigation Keynotes

Aircraft Pressure Instrument

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PURPOSE:

  • Measures the altitude of the aircraft with respect to selected Datum.

 PRINCIPLE:

  •  Movement of capsule with respect to change in static pressure.

Altimeter = Static pressure

 

Principle Measures change in Static Px
Errors BLIPTB
Tolerance +/- 60 feet (30,000ft); +/- 80feet (50,000)
Error High → Low → In
  Low → H igh → Ind
30 ft change in Indicated altitude for every
1mb
4% change in Indicated altitude for every
10c
Function Change in static pressure

Errors: (BLIPTB)

  • Blockage error
  •  Lag error
  •  Instrument error
  •  Position error
  •  Temperature error
  •  Barometric error

 

Types of Altimeter:

  1. Simple/ Service altimeter
  1. Sensitive altimeter (increased accuracy & high altitude)
  1. Servo assisted altimeter (removes lag error)

 

Errors: (BLIPDC)

  • Blockage error
  •  Lag error
  •  Instrument error
  •  Position error
  •  Density error
  •  Compressibility error

VERTICAL SPEED INDICATOR (VSI)

Navigation Keynotes

Vertical Speed Indicator

 

 

 

 

 

 

 

 

 

 

 

 

PURPOSE:

  • Measures the vertical speed of the aircraft with respect to selected Datum.

PRINCIPLE:

  • Measures differential static pressure between inside and outside sealing case.

VSI = Static pressure (inside CAPSULE) – static pressure (outside CAPSULE)

PRINCIPLE Px difference between inside & Outside capsule
ERRORS BLIPT
Tolerance NIL (Measure from desired position)

 

Errors: (BLIPT)

  • Blockage error
  •  Lag error
  •  Instrument error
  •  Position error
  •  Transonic jump

MACH METER

Navigation Keynotes

Machmeter

 

 

 

 

 

 

 

 

 

 

 

 

 

PURPOSE:

  • Indicates the ratio between true airspeed of the aircraft to the local speed of sound.

E.g., Mach 1 = one time the speed of sound Mach 2 = twice the speed of sound Mach .8 = 80% the speed of sound

PRINCIPLE:

  • Mach meter is a combined ASI and altimeter.
  •  Measures difference between Dynamic pressure and Static pressure.

Mach meter ratio = (Dynamic) / Static

 

Principle Px difference of Dynamic & Static
Errors BIP
Tolerance Function +/- 0.1M (0.5M → 1. 0 M )

 

ERRORS: (BIP)

  • Blockage error
  •  Instrument error
  •  Position error

Color Coding Of An ASI

White Arc   Flaps/ Gear Operating range
       
Green Arc   Normal operation range
Yellow Arc   Caution range
       
( Vso )Lower end of White Arc   Stalling speed at landing configuration
( Vfe )Upper end of white Arc   Max Flaps/ Gear extended speed
       
( Vs1 ) Lower end of Green Arc   Stalling speed in Clean configuration
( Vno ) Upper end of green Arc (or)   Max normal operation speed
Lower end of Yellow Arc      
 
( Vne ) Upper end of Yellow Arc (or) Red Line Never exceed Speed
( Vmc ) Red line (within white arc)   Min directional Airspeed (Engine failure)
       
( Vyse ) Blue Line   Best ROC single engine Airspeed
( Vmo ) Red and white stripes   M crit. Max allowable airspeed
       
( Vlo/ Vfo ) White arc   Max gear/ Flaps operation speed
( Vle/ Vfe ) Upper end of white Arc   Max gear/ Flaps extended speed
       
V1   Decision speed
Vr   Rotation speed
       
Va   Maneuvering speed
       
V2 Take off safety speed at screen height (35ft) engine failure
V3   Takeoff safety speed at screen height (35ft) , normal operation  
     
     
V4   Takeoff safety speed at 400 ft
     
Vat   Threshold safety speed at Fence height (50ft), normal operation  
     
     
Vat 1/2/3/4   Threshold safety speed at fence height (50ft) with 1/2/3/4 engine failure
     
     
Vat0 Threshold safety speed at fence height (50ft) in high drag configuration

 

Navigation notes for reference

ERRORS IN PITOT STATIC INSTRUMENTS

Blocked Static; Pitot & Drain hole open

 

Altimeter Frozen
Vertical speed indicator   Zero
Airspeed indicator   Under reads (climb)  
    over reads (descent)

Static Open; Pitot & Drain hole blocked

 

Altimeter   Normal
Vertical speed indicator   Normal
Airspeed indicator   Acts as an Altimeter  
    Under reads (Descent)
over reads (Climb)

Static Open; Drain hole open; Pitot blocked:

 

Altimeter Normal
Vertical speed indicator Normal
Airspeed indicator Zero

Navigation notes for reference

 

GYROSCOPIC INSTRUMENTS

GYROSCOPE:

  • Gyroscope is a device used to measure orientation based on the principle of Angular momentum.
  •  Rigidity and precession are the two main principles of Gyroscope.
Navigation Keynotes

Gyroscope

 

 

 

 

 

 

 

 

 

 

 

Components of Gyroscope:

  • Gyroscope comprises of a rotor spinning about an axis passing through its center of gravity. X-X
  •  The spindle is mounted in a ring known as gimbal X-X
  •  This in turn mounted on outer gimbal Y-Y
  •  Outer gimbal is mounted on a frame about Z-Z Axis.

RIGIDITY

  • Spin axis of a gyro continues to rotate in a same plane of rotation though it is been disturbed by an external force.

Rigidity = (SI)/ F

S = rpm

I = Inertia

F = External force

FACTORS AFFECTING RIGIDITY:

  • Dist between mass to axis
  • Rpm
  • Mass
  • External force

PRECESSION

  • Angular change in direction of spin axis when acted upon external force.
  • Direction of precession is governed by external force resulting in change of plane of rotation, i.e., 90° ahead of the spinning axis.
  •  Gyroscope cannot precess about its axis of rotation.
  •  Precession can takes place about either of the two axis at right angles to the plane of rotation.

Precession = F/ (SI)

Precession 1/ Rigidity

 

TYPES OF GYROSCOPE:

 

FREE/SPACE GYRO (INS) 3axis rotation Freedom 

2 axis – precession freedom

    Gyro axis direction is maintained w.r.t to free point in space    
           
   TIED GYRO (DGI)     3axis rotation freedom

2axis – precession freedom

    Gyro axis is maintained with respect to external force applied (horizontal axis tied gyro)  
   EARTH GYRO (AI)     3 axis rotation freedom

 2axis – precession freedom

    Gyro axis is maintained with respect to earth’s gravity (vertical axis rate gyro)    
   RATE GYRO (TC)     2axis rotation freedom

1 axis – precession freedom

    Horizontal Axis Rate Gyro  
   

FREE GYRO:

  • The gyroscope must have a freedom for the rotor to rotate and precess.
  • The gyroscope which has a freedom to precess in either of two axis at right angle to the plane of rotation is called as free gyro.
  • Number of degree of freedom of precession of any gyroscope is the same as its number of gimbals.
  •  Gyro has a freedom of movement of three axis X-X, Y-Y, Z-Z.

TIED GYRO:

  • Directional gyro provides the pilot with aircraft heading information and so its reference axis is aircrafts vertical axis.
  • The gyro rotor must be sensitive to the movement about its vertical axis.

 

GYRO ROTOR AXIS SENSITIVITY:

 

TYPE AXIS SENSITIVITY SPIN AXIS
Directional Gyro –F Around Vertical axis (A-A) – Turn   Horizontal axis spindle
  Attitude Indicator  – D    Around Longitudinal (C-C) -Bank Around Lateral (B-B) Pitch       Vertical axis spindle
  Turn coordinator– E
     Around Vertical axis (A-A) -Yaw   Horizontal axis spindle
 

WANDER:

 

WANDER

Angular change in spin axis of a gyro

DRIFT                                                                          TOPPLE

Angular shift in horizontal plane                         Angular shift in vertical plane

15 Sin (lat)                                                      15 Cos (lat)

 

 

Drift

REAL                                                                                APPARENT

                                      Mechanical imperfection.                                                             Earth rotation.

                                       Worn-out bearing.                                                                      Transport wander.

                                      even mass distribution.                                                              (GS/60tan(lat)

 

Total drift = real + Apparent

Total drift = real + [ (G/S)/60 ∗ {tan (lat)} + 15 sin(lat)]

APPARENT DRIFT:

  • Imagine the gyro is at true north pole, where all the directions are to south, with spin axis aligned to Prime meridian.
  • Alignment of the spin axis is to unknown point in space.
  •  After an hour the spin axis appears to have drifted 15° (Due earths rotation of 15° / hour)
  •  the above phenomena is called as earth wander
  •  same gyro when taken to equator and aligned to north will not suffer from drift as alignment (north pole) remains as so.
  • As the rate of alignment changes with respect to the latitude the drift is computed as 15*Sin latitude°/Hr.

APPARENT DRIFT:

  • Imagine the gyro is at true north pole, where all the directions are to south, with spin axis aligned to point in space.
  •  After an hour the spin axis appears to have no topple.
  •  same gyro when taken to equator and aligned to a meridian and measured after an hour, gyro maintaining rigidity may appear toppled by 15°
  • As the rate of alignment changes with respect to the latitude the topple is computed as 15*Coslatitude°/Hr.

Horizontal Axis Gyro:

  • @ Poles : No Topple; Only drift
  •  @ equator : Only topple; No drift

Vertical Axis Gyro:

  • @ Poles : No topple; No drift
  •  @ Equator : Only topple; No drift

Note: In northern hemisphere DGI reading will decrease with rate of Earth wander

 

Aircraft flying EAST   Reading will reduce @ faster rate  
             
    Aircraft flying WEST     Reading will reduce @ slower rate  
           
Eg:   Aircraft flying North     Reading will reduce @ increasing rate  
           
    Aircraft flying South Reading will reduce @ decreasing rate

aircraft at 50°N/S @ heading 270°

  • Drift = 15 * sin (lat) = 15 * sin (50) = 11.5°/ Hr
  •  Northern hemisphere – indication would under read by 11.5° (i.e.,258.5°) after an hr.
  • Southern hemisphere – indication would over read by 11.5° (i.e.,281.5°) after an hr.

Eg: aircraft at 70°N/S @ heading 270°

  • Drift = 15 * sin (lat) = 15 * sin (70) = 14°/ Hr
  •  Northern hemisphere – indication would under read by 14° (i.e.,256°) after an hr.
  •  Southern hemisphere – indication would over read by 11.5° (i.e.,284°) after an hr.

 

LATITUDE NUT:

  • Latitude nut is provided in DGI to reduce earth rate wander
  •  It is slaved “OUT” in Southern hemisphere – Clock wise direction
  •  It is slaved “IN” in northern hemisphere – anti clock wise direction

 

DGI

DIRECTIONAL GYRO INDICATOR

PURPOSE:

  • Indicates heading of an aircraft.

PRINCIPLE:

  • Works on the principle of gyro rigidity.
  •  Horizontal axis of a tied gyro is aligned with the lateral axis of the aircraft.
  • DG is less rigid than a Attitude indicator.

TYPE:

  • Horizontal axis tied gyro
  • DGI are normally air driven @ the speed of 12,000rpm.

LIMITATION:

  • Requires often synchronization with the magnetic compass after engine start & at frequent time intervals (WANDER).
  • Compass scale is attached to the outer gimbal.
  •  It has two degree of freedom of precession.

ATTITUDE INDICATOR

PURPOSE:

  • Indicates pitch and bank information.

PRINCIPLE:

  • Works on gyro rigidity to maintain gyro axis vertical.

TYPE:

  • Vertical axis earth gyro.
  •  Air driven = 15,000rpm
  •  Electrically driven = 22,000rpm

LIMITATION:

 

Old aircraft ±55° ±90°
  Modern aircraft   ±85° ±180°

 

CONSTRUCTION:

 

Inner gimbal Pitch indication
Outer gimbal Bank indication
Aircraft model Glass
Sky plate Outer gimbal

ERRORS:

  1. Acceleration/ deceleration error
  1. Turning error

 

TURNING ERROR:

  • 001 deg              Under reads bank angle; indicates climb
  • 181 deg               Error reduces

ACCELERATION ERROR:

 

Acceleration Indicates Climb
Deceleration Indicates descent ↓;  Left turn ←
     

 

TSI

TURN & SLIP INDICATOR

Navigation Keynotes

Turn and Slip Indicator

 

 

 

 

 

 

 

 

 

 

 

 

 

PURPOSE:

 

Turn & slip indicator Indicates rate of turn and direction of turn  
     
Turn coordinator   Indicates rate of turn and quality of turn

Note: QUALITY of a turn: Relationship between rates of turns and bank angle.

PRINCIPLE:

  • Gyro Precession.

Note: this is the only instrument to use gyroscopic precession.

TYPE OF GYRO:

  • Horizontal axis rate gyro.

 

PROPERTIES:
RPM Over read  
   
↑G force Over reads  4500 rpm to 9000rpm  
↑Tension Under reads  Rate of turn = g(tanθ)/ V
  • Radius of turn = v2/ g(tanθ)

 

Rate 1 turn 3°/sec
  Rate 2 turn   6°/sec
   Rate 3 turn  9°/sec
   Rate 4 turn   12°/sec

ERRORS OF TSI:  (Ro Go Tu)

Note: difference between turn/ slip indicator & turn coordinator is that the longitudinal axis of gyro gimbal is inclined @ 30°, so that it indicates Turn & Bank angle.

 

Skid (out) Slip (in)  
Coordinated    
↑Centrifugal force ↓Centrifugal force =Centrifugal force
   
↓Acc. Due to gravity ↑Acc. Due to gravity = Acc. Due to gravity

 

MAGNETISM

TYPES OF MAGNET

HARD IRON MAGNET:

  • Magnet which is difficult to magnetize but once formed, tend to retain their magnetic properties.

SOFT IRON MAGNET:

  • Magnet which is easier to magnetize but tend to change its magnetism when magnetic force is removed.

 

TYPES OF MAGNETIC COMPONENTS:

a) Hard iron component

b) Soft iron component

 

HARD IRON COMPONENT:

  • A magnet component which is permanent in nature and acquires during manufacturing.
  •  Does not change with latitude/ heading.

SOFT IRON COMPONENT:

  • Induced magnetic component due to earth’s magnetic field.
  •  Changes with latitude/ heading.

 

AIRCRAFT PERMANENT MAGNET

3 Hard iron component                                          2 soft iron component

(Component P/ Q/ R)                                              (Component Cz/ Fz)

 

 

COMPONENT P:

  • Permanent magnetism around longitudinal axis of the aircraft
  •  It is +ve when South pole is ahead of compass

 

COMPONENT Q:

  • Permanent magnetism around lateral axis of the aircraft
  •  It is +ve when South pole is right of compass

 

COMPONENT R:

  • Permanent magnetism around vertical axis of the aircraft
  •  It is +ve when South pole is below compass

 

COMPONENT CZ:

  • Vertical soft iron component along longitudinal axis of the aircraft

COMPONENT FZ:

  • Vertical soft iron component along lateral axis of the aircraft.

COEFFICIENT B:

  • Component P + Component Cz

Coefficient B = (Dev East – Dev west)/ 2

Coefficient B = Bsinθ

Note: Least deviation = N/ S direction

Max deviation = E/ W direction

 

COEFFICIENT C:

  • Component Q + Component Fz

Coefficient C = (Dev north – Dev south)/ 2

Coefficient C = Ccosθ

Note: Least deviation = E/ W direction

Max deviation = N/ S direction

 

COEFFICIENT A:

  • Real coefficient A = due to horizontal soft iron component
  •  Apparent coefficient A = due to misalignment of lubber line.

Coefficient A = (Sum of deviation 4/8)/ (4/8)

Total deviation on compass = A + B (sinθ) + C (cosθ)

 

COMPASS SWING:

  • It is a process of correcting compass heading with real heading close to magnetic heading.
  •  Coefficient B & C are corrected with North & East heading respectively.
  •  Coefficient A is adjusted with lubber line.
  •  Residual deviation is corrected with compass card fitted on cockpit.

 

Navigation notes for reference

MAPS & CHARTS

MAPS:

  • They contain geographical features depending upon the scale of map. g., Roadway map, Railway map, river, canal e.t.c.,

 

CHARTS:

  • They contain limited information pertaining to specific purpose. g., Met charts, Nav charts etc.,
  • Only major geographic features are shown on charts.

PROJECTION:

  • Maps and charts are created with Light source and graticules called Projection.

PROJECTION

 

PERSPECTIVE NON- PERSPECTIVE
 (Light source & graticules)  (Mathematical Calculation)
  • Cylindrical (simple cylindrical & Mercator projection)
  •  Conical (simple conical & lamberts conformal)
  •  Azimuthal (Azimithal & stereo orthomorphic)

 

PROSPECTIVE PROJECTION:

  • Graticules of earth are projected on a sheet of paper with the light source.

NON- PROSPECTIVE PROJECTION:

  • Created mathematically.

 

ORTHOMORPHIC / CONFORMAL:

  • Orthomorphic is a property of a projection in which bearings are correctly shown in all directions.

Properties of ORTHOMORPHISM:

  • Latitudes & longitudes cross at 90°
  •  Scales should be constant within close proximity.

 

SIMPLE CYLINDRICAL:

  •  Latitudes and parallel of latitudes are parallel straight and not equidistant, distance increases from equator to poles.
  •  Convergency between meridians are Zero
  • Points of projection is center of earth
  • Rhumb line is a straight line
  •  Great circle is a curved line
  •  They are not orthomorphic

MERCATOR PROJECTION:

  • Mathematic corrections are made to simple cylindrical to make it orthomorphic.
  •  Scale is varied at constant rate & extends in N/S direction.
  •  Scale is least at equator and max @poles.
  •  Polar Regions are not shown, it extends only up to 70° – 80° from the equator.
  •  Types of Mercator’s are:
  1.  Simple Mercator
  2. Transverse Mercator
  3. Oblique Mercator
  4. It is used for Met charts in India

Scale @ Latitude = [Scale @ equator (1/Cos(lat)]

 

CONICAL PROJECTION:

  • Point of tangency on a particular latitude called as Latitude of Origin.
  •  Meridians converge to nearest pole
  •  Latitudes are arc of the circles and are not equidistant, dist between them increases away from latitude of origin.
  •  Great circles are Straight lines and Rhumb lines are curved (concaved)
  • They are not orthomorphic.

LAMBERTS CONFORMAL PROJECTION

  • It is a conical projection between two std parallels
  •  Prospective projection but constructed mathematically
  •  It is orthomorphic only between std parallels
  •  Meridians are straight lines converging to poles
  •  Latitudes are arc of concentric circles
  •  Scale is constant between std parallels. Outside it expands drastically
  •  Between std parallels scale expands to either side of latitudes of origin
  •  Scale is least at latitude of origin and increases towards poles
  •  Scale is ≤1%
  •  Std parallels are selected by changing cone angle
  •  Great circles are straight lines and rhumb lines are curved lines
  •  Used in Jeppesen charts, airway charts
  •  Plotting radio waves are easier
  •  Great circles can be easily tracked and drawn
  •  Cannot be used in higher latitudes
  •  Measuring track is on midway latitude
  •  Convergency is correct in latitude of origin & scale is correct in std parallels

 

ZENITHAL/ AZIMUTHAL PROJECTION:

  • Latitudes are concentric circles and are not equidistant. It increases from poles to equator
  •  Great circles are straight lines and Rhumb lines are curved
  • Not orthomorphic projection

 

POLAR STEREOGRAPHIC PROJECTION

  • Scale is varied at the rate of sec2 from poles to equator
  •  It is an Orthomorphic projection
  •  Covered only to polar region
  •  Used only to fly on one hemisphere only
  •  Used to fly in polar region

 

CRUISING LEVELS

  • Flights in India follows Quadrental cruising levels up to FL140 & semi circular levels are followed from FL150. Tracks are based on magnetic tracks. Quadrental Cruising Level

Semi Circular Cruising System

  • The lowest level available is FL040
  •  The highest level available is FL450

 

FLIGHT MANAGEMENT SYSTEM (FMS)

  • Used to manage aircraft’s performance and route navigation.
  •  The computed data can be used to a) advise crew, b) to direct auto throttle or auto pilot to steer the aircraft.
  •  Flight Management System (FMS) collects data from various aircraft systems, which are then fed to Flight Management Computer (FMC)

Flight Management Computer (FMC)

  • It is used to compute aircraft’s performance and route navigation.
  • The main section of FMS is FMCS (Flight management computer systems), which has two FMC and two CDU.

Control Display Unit (CDU)

  • CDU is an input devise.
  •  Used by the crew to access the FMC.

EICAS (Engine indication and crew alerting System)

  • EICAS is a system being a part of EFIS, consisting computer to compute engine parameters and displaying through ECAM.
  •  It helps in displaying primary engine displays, crew alerts and status display.
  •  Two EICAS computers receive inputs from engine and system sensors, the information is computed and displayed in CRT/ LCD screens which are placed one over the other.
  •  Primary engine indications (EPR, N1, EGT, N2) and Crew alerts are displayed on the upper screen
  • Secondary engine indications are displayed on the lower screen.

 

CREW ALERTING:

 

Warnings (Level A) Red illumination Airplane system requires crew awareness and to prompt immediate action 
Cautions (Level B)  Amber illumination Airplane system requires crew awareness and not necessary to prompt immediate action
 Advisories (Level C)  Amber Illumination  Airplane system requires crew awareness and to prompt immediate action on time basis

 Electronic Flight Instrumentation System (EFIS)

  • An Electronic Flight Instrument System (EFIS) is a flight deck instrument display system in which the display technology used is electronic.
  •  EFIS normally consists six screens. They are primary flight display (PFD), multi-function display (MFD) and Engine Indicating and Crew Alerting System (EICAS) display, in liquid crystal display (LCD)

 

ECAM (Electronic centralized Aircraft Monitoring)

  • ECAM is a system being a part of EFIS displays Engine indications, crew alerts and status display. It consists of two screens one over the above displaying
  •  ENGINE/ WARNING (E/W)
  •  SYSTEM/ STATUS (S/S)

 

Engine/ Warning Displays:

  • Engine parameters
  •  Fuel on board
  •  Slats & flap position
  •  Warning and caution messages
  •  Memos when failures exist.

 

The system/ status Displays:

  • System synoptic diagram
  •  Status message

 

ECAM COLOR CODING:

 

RED WARNING
AMBER CAUTIONS
GREEN NORMAL LONG TERM OPERATINS
WHITE FOR FUNCTIONS NOT IN NORMAL OPERATIONS (Switch off position)
 Blue  FOR ACTION TO BE CARRIED

 

Flight Director system:

  • Flight Director System (FDS) provides guidance information on required aircrafts maneuver in pitch and roll to regain or maintain the programmed flight path.

 

AIR DATA COMPUTER (ADC)

  • ADC converts pressure energy to electrical signals
  •  Its receives Pitot, static pressure and temperature from normal and alternate sources and converts them to electric signals and transmits them to various indicators and systems.
  • ADC can be programmed to calibrate necessary corrections for pressure error, barometric pressure change and compressibility effects.
  •  Generation of the signals in ADC are forwarded to FMS for subordinate computations and operations
  •  Loss of air data inputs activates warning logic circuit within ADC, which cause warning flag ot appear on the associated indicators and annunciators.

 

SYSTEMS USING ADC OUTPUTS

  • Flight Director
  • Automatic thrust control
  • Automatic flight control
  • Cabin pressurization
  • Altitude reporting
  • Flight management
  • GPWS
  • Flight Data recorder
  • Stall warning

 

TOTAL AIR TEMPERATURE MEASURING PROBE: (Temperature transducer)

Air temperature thermometer is divided in two basic types:

  • Direct reading
  •  Remote reading

 

DIRECT READING:

  • Thermometer consists of two bimetallic strips (INVAR & BRASS).
  •  As the strip is heated due to increase in temperature, brass expands due higher coefficient.
  •  The strip curls are measures which results due to brass bend.

 

REMOTE READING:

  • The air is made to pass through the probe, which is made of nickel – plated beryllium copper for better thermal conductivity.
  • In flight, the flows through the probe and turns right angle to the sensing element.
  •  A pure platinum wire resistance – type sensing element is used.
  •  As the airflow passes the element, it detects the temperature.
  •  The resistance of the element changes as the temperature changes. (Element is a resistance bridge circuit)
  • A heating element is mounted integral with the probe to prevent the formation of ice and is of self compensating type in that as the temperature rises so does the element resistance rises, thereby reducing the heating current.
  • When the aircraft is at ground during rest or at slow speed the engine bleed air is used to create a reduction of pressure within the casing of the probe, this has the effect of drawing the air to pass through the probe at higher rate.

 

 

PRESSURE TRANSDUCER:

  • It utilizes Piezo-electric effect, i.e., converting pressure/ dynamic energy to electrical energy.
  • A diaphragm composed of thin quartz discs are impregnated with metallic particles is subjected to pitot/ static pressure.
  • The flexing creates electrical charge in the discs.

 

Radio Waves

CYCLE:

  • Complete series of a wave value.

AMPLITUDE:

  • Maximum displacement of a wave from its mean position.

WAVE LENGTH: (λ)

  • Dist between two successive crest and trough.

Frequency: (n)

  • Number of cycles per second. (Hz)
  •  1 cycle/ Sec = 1Hz.

 

1 Cycle/ Sec 1Hz
1000Hz 1 KHz
1000KHz 1MHz

 

1000MHz 1GHz

Frequency (n) = c/ λ

Note: C = Speed of light (3*10^8 m/s); λ = Wave length.

FREQUENCY BANDS:

There are 8 Frequency Bands:

 

VLF 3 KHz – 30KHz
LF 30KHz – 300KHz
MF 300KHz – 3000KHz
HF 3MHz – 30MHz
VHF 30MHz – 300MHz
UHF 300MHz – 3000MHz
SHF 3GHz – 30GHz
EHF 30GHz – 300GHz

 

PROPERTIES OF ELECTROMAGNETIC SIGNAL:

  1. Travel in the speed of Light (3*10^8 m/sec)
  1. Travel along great circle
  1. They get reflected, refracted, diffracted and attenuated.
  1. When passing from lighter medium to denser medium they move towards normal & when passing from denser to lighter medium they move away from normal of the transmitter.

 

TYPES OF WAVE:

SPACE WAVE:

  1. Direct wave
  1. Ground reflected wave

GROUND WAVE:

  1. Space wave
  1. Surface wave

 

NIGHT EFFECT ON RADIO WAVES:

  • During day time electron from the atoms gets detached due to presence of UV rays from the sun, therefore results in the formation of D, E & F layer.
  • During night time due to the absence of UV rays, electron density reduces and D layer disappears.
  •  D Layer = 50Km – 100Km (75Km Avg)
  •  E Layer = 100Km – 150Km (125Km)
  •  F Layer = 150Km – 350Km (225Km)

ANGLE OF INCIDENCE:

  • Angle in which the radio signal makes with the normal is called as angle of incidence.

CRITICAL ANGLE:

  • Angle of incidence at which the first sky wave return is received back to earth surface is called as critical angle.

SKIP DISTANCE:

  • Distance from antenna to the point where first shy wave return is received.

DEAD SPACE:

  • Distance between limit of surface wave to the point where 1st sky wave return is received.

POLARIZATION:

  • When electromagnetic signal is transmitted, electric & magnetic signals travel ⊥ to each other in the direction ⊥ to both the components.

PLANE OF POLARIZATION:

  • The plane in which the electric component lies is called plane of polarization.
  •  Horizontally polarized signal will be transmitted and received by horizontal antenna only.

MODULATION:

  • The process of super imposition of Audio/ information/ intelligence on a high frequency radio wave (carrier wave) is called as modulation.
  •  There four types of Modulation, they are
  1.  Frequency modulation
  1. Amplitude modulation
  1. Pulse modulation
  1. Phase modulation

FREQUENCY MODULATION:

  • When the frequency of a carrier wave is varied in accordance with incoming radio signals with constant amplitude.
  •  Used in Aviation communication, F.M.Radio, television signals.

AMPLITUDE MODULATION:

  • When the amplitude of a carrier wave is varied in accordance with incoming radio signals with constant frequency.
  • Used in A.M.Radio.

PULSE MODULATION:

  • Transmission is made in form of pulse either in Amplitude modulation or Frequency modulation.
  • Used in Primary RADAR.

PHASE MODULATION:

  • The phase of the carrier wave is varied in accordance with incoming radio signals.
  • Used in Global Positioning System (GPS).

 

NON DIRECTION BEACON (NDB)

Navigation Keynotes

NDB

 

 

 

 

 

 

 

 

 

 

 

NDB is an omni bearing radio signal transmitter used for Navigation.

 

NDB 190KHz – 450KHz
ADF   190KHz – 1750KHz
Freq. Band   Upper Low Frequency  
    Lower Middle Frequency
Principle   Bearing by loop theory
Purpose   Gives 360 degree bearing

 

BEARING:

  • Horizontal direction to one object from the other.

RELATIVE BEARING:

  • Direction measured in degrees in clockwise from the reference point of the 1st to the other.

MAGNETIC BEARING:

  • Bearing measured with respect to Magnetic north.

TRUE BEARING:

  • Bearing measured with respect to true north.

WORKING:

  • Aircraft receiver has two aerials. (1. Loop aerial, 2. Sense aerial.)
  •  Resultant of two aerials gives the ADF indication.

LOOP AERIAL + SENSE AERIAL  =  CARDIOD

LOOP AERIAL:

  • Loop aerial has directional properties. It is in the form of “8”.
  •  They have two null points
  •  They suffer 180 degree ambiguity (180* confusion)
  •  Any signal received from NDB produced EMF on vertical arm of the loop.
  • EMF is Max when signal is aligned with the antenna.
  •  EMF is zero when signal is ⊥ to antenna.

SENSE AERIAL:

  • Omni directional antenna, used to resolve 180 degree ambiguity
  •  Output of both the signals result to move RBI pointer.

FACTORS AFFECTING ADF ACCURACY:

  1. Night Effect
  2.  Coastal error
  3.  Quadrantal error
  4.  Loop misalignment
  5.  Static interference

 

NIGHT EFFECT

Cause:

  • During day time all frequencies below HF will be absorbed by ionosphere due to increase in electron density.
  •  At night time due to reduction of electron density (disappearance of D-layer) even MF are refracted back to earth which results in interference in radio signals.

Methods to reduce:

  • Use beacon within 70Nm from the Aircraft position.
  •  Therefore at night NDB range is reduced to 70Nm.
  •  Use beacon which has high transmission power, as direct wave will be stronger.

COASTAL ERROR

Cause:

  • Air density at land is more than sea.
  •  Therefore signal leaving land to sea will move away from normal (i.e., towards coastal area).
  •  Results in error indication of aircraft being closer to the coast than the original position.

Methods to reduce:

  • Use beacon which are at acute angle almost 90degree to the station.
  •  Fly at high altitude.
  •  Use beacon which are closer to station.
  •  Use beacon with high transmission power.

QUADRANTAL ERROR

Cause:

  • Electromagnetic radiations around aircraft interfere with the Aircraft antenna results in error indication.
  •  This is more on quadrantal heading than cardinal heading.

INTERFERENCE ERROR

Cause:

  • When aircraft is flying in the coverage area of more than one NDB result in interfering with both the signal.
  •  This can be reduced by flying with accordance to DOC (Designated Operating Coverage) given in AIP (Airmen Information Publication).

NOTE: NDB protection rage is valid for day only; First instrument affected by thunderstorm is NDB/ ADF.

TYPES OF NDB:

  1. Locator NDB
  •  Low power NDB
  • Range 10Nm-25Nm

2.   Homing/ Holding NDB

  •  Medium Power NDB
  • Co-located with ILS
  • Used for holding
  • Range up to 50Nm
  1. Enroute NDB
  •  High power NDB
  • Long range navigation

 

FACTORS AFFECTING NDB RANGE

  1. Terrain (Plains range > Hills; Sea range > plains range)
  1. Transmission power (Range ∝ √Transmission Power)
  2. Frequency (Frequency Range  ↓      ↑ Ground wave attenuation)
  3. Night effect (Range  ↓ due to night effect)

 

 

VOR

Navigation Keynotes

Doppler VOR

 

 

 

 

 

 

 

 

 

 

 

(VHF OMNI DIRECTIONAL RADIO RANGE)

 

Purpose Transmits 360 Magnetic radials  
     
Principle   Bearing by phase comparison  
Frequency   108MHz – 118MHz  
Freq. band   VHF

RADIAL:

  • Magnetic track radiating outwards from the station.

WORKING:

  • Ground transmitter has two aerials 1) Fixed Aerial, 2) Electronically rotated.

FIXED AERIAL:

  • Omni directional antenna, transmits at 30Hz F.M Reference signal
  •  Reference signal is received at same phase around the transmitter.

ELECTRONICALLY ROTATED:

  • Transmits Variable signal at 30HZ in A.M.
  •  Rotates at 30 cycles/sec, signal is received at different phase around 360.
  • Aircraft VOR receiver measures phase difference and gives bearing information.
  • Both the signals are in same phase at 360.

FIXED AERIAL + ROTATING AERIAL = LIMACON

OBS (OMNI BEARING SELECTOR)

  • Knob which is used to select the required bearing.

CDI (COURSE DEVIATION INDICATOR)

  • Needle which shows the degrees of deflection.

TO/ FROM INDICATOR:

  • This indicates whether the aircraft is towards/ away from the station.
  •  Does not show aircraft is to or from the station.

CONE OF CONFUSION:

  • VOR are horizontally polarized signal.
  •  Inclined at 60* – 80* from the ground level.
  •  Above VOR no signals are transmitted.

FACTORS AFFECTING VOR RANGE:

  1. Transmission Power
  1. Line of Sight (LOS)
  1. Designated operating coverage (DOC)

FACTORS AFFECTING VOR ACCURACY:

  1. Site error
  1. Airborne equipment error
  1. Propagation error
  1. Pilotage error

VOT (VOR TEST EQUIPMENT)

VOR Accuracy:

 

  In ground   +/- 4 degree    
  Airborne   +/- 6degree    
  Dual VOR   +/- 4degree    
  check        
VOT:      
         
180 OBS +/- 4 * deflection To indication
360 OBS +/- 4* deflection FROM indication

NOTE:

  • Morse code is transmitted every 10Sec.
  •  VOR does not suffer from Night effect.
  •  It has failure warning flag, small aerial & free from static interference.
  •  Max Deflection for a VOR +/- 10 degree

DOPPLER VOR:

  • Has 51 aerials
  • One aerial at the center, transmits 30Hz A.M Reference Signal.
  •  50 aerials around one aerial transmit 30Hz F.M Variable Signal.
  •  It rotates in anti clock direction.

 

INSTRUMENT LANDING SYSTEM (ILS)

Navigation Keynotes

ILS

 

 

 

 

 

 

 

 

 

 

PURPOSE:

 

Azimuth Information Localizer
Range Information    Marker beacon
  Glide path    Glide Slope

LOCALIZER

 

Purpose Gives azimuth information (All odd 1st   decimal)  
     
Frequency   108MHz – 112MHz
Band VHF
Principle Bearing by lobe comparison

 

NOTE:

  1. Localizer is placed 300M from upwind of runway.
  1. Max deflection of a localizer is +/- 2.5degree.

MARKER BEACON

 

Outer Marker Blue (– — –) 400Hz 600m 3.5Nm-6Nm
Middle Marker Amber (  .– –) 1300Hz 300m 3500feet
Inner Marker White (. . .)   3000Hz 100m 1050Feet

Note:

  1. Glide slope is fixed 150m to side of runway.
  2.  Max deflection for a glide slope is +/- 0.7 degree.
  3.  A/C with more than half of full scale deflection should initiate MSD approach.

 

FALSE GLIDE SLOPE:

  • Due to aerial propagation, the twin lobe pattern of glide slope is repeated.
  • First Glide slope appears at 6degree from ground. (i.e., 3degree from actual glide slope)

INDICATIONS OF FALSE GLIDE SLOPE:

  • Very high ROD
  • Very high altitude over OM
  •  Loc failure flag may appear

CATEGORIES OF ILS:

 

Category Decision Height RVR
(DH)
I 200feet   550meter
II   100feet   350meter
III a   ↓10 0 feet   200meter
III b   ↓50 feet   50meter
III c   Zero   zero

RADAR

(RADIO DETECTION AND RANGING)

RADAR

PRIMARY RADAR                                                               SECONDARY RADAR

  1. Pulsating Radar
  2. Continues Wave Radar

PULSE WIDTH:

  • Time interval lapsed between start of one pulse to the end of the same pulse.

 

PRP/ I/ T:

  • Time interval lapsed between start of one pulse to the start of the next pulse.

PRF/ R:

  • Number of pulses per second.

(PRP) (1/ PRF)

  1. Range = (C/ 2PRF)

BEAM WIDTH:

  • Width of the transmitted Radar beam.

PRINCIPLE OF RADAR:

  • Echo and Search light
  • (Echo = Range & Search light = Angular Information)

BAND:

  • VHF and above.
  •  (i.e., 30MHz – 300MHz) & Line of Sight.

Note:

 

ü Radar range↑  ; Frequency ↓
ü Frequency↑  ; Beam width ↓
  • Radar range is a function of PRF
  • Radar range is a function of Pulse width
  • Angular resolution is a function of Beam Width

 

PRIMARY RADAR SECONDARY RADAR
Stand alone system does not require any assistance. Requires Assistance from the object being identified  
 
     
  Transmitter and receiver are at same place (one set) Transmitter and receiver are at both the points. (two sets)
 
     
  Information is obtained in a single pulse Information is obtained as ex-change of Pair of pulses  
 
     
  Range ∝ 4√Transmission Power Higher phase than primary
     
  Prone to Disturbance Free from disturbance

 

 

Max. Radar range C/ 2PRF
   
  Min. Radar range   Ct/ 2

 

DME

(DISTANCE MEASURING EQUIPMENT)

WORKING:

  • Aircraft selects its operating frequency which is paired with VOR.
  •  Aircraft equipment sends series of Pair of pulses (150 PRF) with regular time interval of 12 μ sec.
  •  Ground equipment receives it and transmits it back (27 PPS) {between 24PPS – 30 PPS} with the time delay of 50 μ sec.
  •  The estimation of distance is computed with the (time elapsed from transmission to reception) + (50 μ sec).
  •  DME ground station can respond to 2700PPS. i.e., 100 aircraft on lock mode.
  •  DME can respond to 126 aircraft on search mode.

Note:

  1. DME never indicates Zero instead converts vertical height in Nm. Over the station
  2. Slant range is negligible to 1000ft/ Nm.

ILS DME:

  • Co-located with glide slope equipment.
  •  Indicates zero at ILS threshold.
  •  Range is with Localizer coverage area.

FREQUENCY PAIRING:

  • VOR DME is frequency paired and serves same station.
  •  They can also be frequency paired and to serve same station being far apart ≤ 7Nm from each other.
  •  In that case VOR will have alphabet “Z” at the end.

MORSE CODE:

  • VOR DME transmits every 10Sec.
  • DME inop – transmits only every 30Sec.
  •  VOR inop – VOR failure warning flag comes on.

TACAN

Navigation notes

TACAN Antenna

 

 

 

 

 

 

 

 

 

 

 

 

 

(TACTICAL AIR NAVIGATION SYSTEM)

  • Performs same as VORTAC
  • Used by military for Azimuth and range information
  • Civil Aircraft uses it for Range information only.

 

SSR

(SECONDARY SURVEILLANCE RADAR)

 

Principle Mode & Code Pulse
Frequency 1030MHz – 1090MHz
Band UHF
Purpose Used by ATC for aircraft identification

 

TYPES OF TRANSPONDER:

 

Mode A 8μsec PRP Identification of Aircraft
Mode B   17μSec PRP   Standby for Mode A
     
Mode C   21μSec PRP   Altitude information in steps of 100feet.
     
Mode S       Altitude information (25 feet) and acts as data transponder

Note:

  • Mode C & S should not be used if altitude error is ≥ 200feet.

SQUAWK CODES:

 

7500   Hijack  
  7600   Communication failure    
       
  7700   Emergency  
  2000   No code allotted  
  0000   Transponder failure    
   
  1200 VFR flight

Note

There are 4096 Squawk  available.

FRUITING:

  • When the aircraft flies with the coverage area of more than one ground station results in interference.
  •  This interference is called as fruiting.
  •  This can be reduced by using different PRF technique.

GARBLING:

  • When two aircrafts are operating with same station flying close to each other results in no synchronized interference with over lapping response at the ground station called Garbling.
  •  This can be reduced by using Killer Circuit at the ground station.

BITE (BUILT IN TEST EQUIPMENT):

  • It is a spring loaded switch for internal check.
  •  When pressed it turns on and turns off automatically within 15Sec – 20Sec.
  •  When turns off ≤ 15 sec System is serviceable
  •  Stays on ≥20Sec system is unserviceable.

TCAS

(TRAFFIC COLLISION AVOIDANCE SYSTEM)

  • Traffic Collision Avoidance System – Gives aural and visual traffic warning for Pilots onboard.

 

TCAS

TCAS I (traffic advisory only) TCAS II (traffic & resolution adv)
 
a) Warns Pilot (40Sec before collision) a)R.A in vertical plane only
b)Audio warning (TRAFFIC –TRAFFIC) b)Uses mode C / S transponder
 
c)Visual warning through light beep. C)Determines relative vertical position

 

R.A

  • Preventive R.A
  • Corrective R.A

Preventive R.A:

  • Prevents conflictions rather resolving them.

E.g., “MONITOR VERTICAL SPEED “

Corrective R.A:

  • Corrective action is given.

E.g., “CLIMB CLIMB” / “INCREASE CLIMB”

 

TCAS warning symbols:

TRAFFIC ADVISORY:

  • Some other conflicting traffic.  =  (Cyan/ white hollow diamond)
  • Proximate traffic (<6nm; +/- 1200’)      =  (Cyan/ white solid diamond)
  • Potential threat   =  (Yellow solid circle)

 

RESOLUTION ADVISORY:

 Collision threat  =  (Red solid square)

 

WORKING OF TCAS

  • TCAS is a Secondary surveillance radar
  •  Interrogates with transponder in nearby aircraft.
  •  Computes and replies data aurally / visually.
  •  Max range – 30Nm
  •  Within terminus – 6Nm
  •  Outside terminus – 12Nm. (used range)

WHAT IS ACAS?

  • European Airborne collision Avoidance system (ACAS II).

WHAT IS GPWS?

  • Ground Proximity warning system.
  •  Alerts pilot aurally & visually when aircraft is dangerously close to ground.

INPUTS:

  1. Radio altimeter
  1. Vertical Speed Indicator
  1. Glide slope
  1. Flaps
  1. Landing gears

Note: GPWS does not obtain information from simple altimeter.

MODES OF GPWS:

 

 MODE FLIGHT HAZARD  ENVELOPE ALERT WARNING
1. Excess ROD 50’ – 2450’ AGL  “SINK RATE” WHOOP WHOOP PULL UP  RED WARNING
2.  Excessive terrain    
2a. Not in ldg configuration 1800’ “TERRAIN TERRAIN”
 2b.  In ldg configuration 790’
 3.  (-ve) ROC after takeoff  50’ – 750’  “DON’T SINK”
 4.  Unsafe Ldg Configuration    
 4a.  Gear up  500’  “TOO LOW GEAR”
4b. Flaps up  200’  “TOO LOW FLAPS”  “
 

 

         
5. Glide slope 100’ – 500’ “GLIDE SLOPE” NO WARNING
 6.  Over D.H MINIMUM S NO WARNING

 

WHEN CAN YOU OVER RIDE GPWS

  • Flying in daytime
  • 1Km horizontally clear of clouds
  • Captain can decide to override a GPWS when the aircraft is
  •  1000’ vertically clear of clouds
  • 8 1/2 Km of clear visibility
  • Obviously not in danger.

 

WHAT IS THE DIFFERENCE BETWEEN GPWS & EGPWS

  • EGPWS alerts pilots as same as GPWS thereafter it also warns Pilots for Wind shear and Bank angle during final approach.

 

PILOT’S ORDER OF PRIORITY

  1. Wind shear
  1. GPWS
  1. TCAS

 

PILOT’S ACTION DURING TCAS/ GPWS ALERT:

TRAFFIC ADVISORY ALERT:

  • Contact ATC
  •  Confirm traffic
  •  Best course of action

RESOLUTION ADVISORY ALERT:

  • Disengage auto pilot
  •  Follow TCAS instrument
  •  Contact ATC

GPWS ALERT:

  • Stop descent
  •  Gradually apply power
  •  Best course of action
  •  Contact ATC

RADALT

(RADIO ALTIMETER)

 

Purpose Measures height of the aircraft
Frequency 4.2GHz – 4.6GHz
Wavelength λ 7Cms
Band SHF

PRINCIPLE:

  • Time interval lapsed between transmission and reception of frequency modulated continues wave (FMCW).

ACCURACY:

  • 5feet ± 3%

Note:

 

ü Indicates height in landing configuration ↓2 50 0 feet A G L
ü It does not transmit pulses it transmits continues carrier wave

 

 

MLS

(MICROWAVE LANDING SYSTEM)

 

Principle Time reference scan beam (TRSB)
Frequency 5.03GHz – 5.09GHz
Band SHF
Wavelength λ 6cms

 

LIMITATIONS OF MLS:

  • Interference from obstructions below
  • Only one glide slope of 3°
  •  No false glide slope
  •  Longer recovery time
  • Not useful in takeoff directions.

AZIMUTH INFORMATION:

Horizontal Coverage  10NM  plus/minus 20 deg, 20 nm plus/ minus 40 deg

 

 

BLACK BOX:

  • Black box is a bright yellow/ orange colored recording devise consisting FDR & CVR.

 

FLIGHT DATA RECORDER (FDR) :

  • A flight data recorder (FDR) (also ADR, for accident data recorder) is an electronic device employed to record any instructions sent to any between electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters. Another kind of flight recorder is the cockpit voice recorder (CVR), which records conversation in the cockpit radio communications between the cockpit crew and others (including conversation with air traffic control personnel) as well as ambient sounds
  •  recorder must be able to withstand an acceleration of 3400 g (33 km/s²) for 6.5   This is roughly equivalent to an impact velocity of 270 knots (310 mph) and a deceleration or crushing distance of 450 cm. Additionally, there are requirements for penetration resistance, static crush, high and low temperature fires, deep sea pressure, sea water immersion, and fluid immersion.
  •  Most FDRs record approximately 17–25 hours worth of data in a continuous loop
  •  FDRs are typically double wrapped, in strong corrosion-resistant stainless steel or titanium, with high-temperature insulation They are usually bright orange. They are designed to emit a locator beacon for up to 30 days, and can operate immersed to a depth of up to 6,000 meters (20,000 ft)

COCKPIT VOICE RECORDER (CVR):

  • A cockpit voice recorder (CVR), often referred to as a “black box”, is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents. This is typically achieved by recording the signals of the microphones and earphones of the pilots headsets and of an area microphone in the roof of the cockpit

 

  • A standard CVR is capable of recording 4 channels of audio data for a period of 2 hours. The original requirement was for a CVR to record for 30 minutes, but this has been found to be insufficient in many cases, significant parts of the audio data needed for a subsequent investigation having occurred more than 30 minutes before the end of the recording.

 

EMERGENCY LOCATOR TRANSMITTER (ELT):

  • Distress radio beacons, also known as emergency beacons, ELT or EPIRB, are tracking transmitters which aid in the detection and location of boats, aircraft and people in   Strictly, they are radio beacons that interface with worldwide offered service of Cospas- Sarsat, the international satellite system for search and rescue (SAR). When manually activated, or automatically activated upon immersion, such beacons send out a distress signal. The signals are monitored worldwide and the location of the distress is detected by non geostationary satellites, and can be located by trilateration in combination with triangulation, respecting the varying quality of the signal received
  •  It transmits signal at a frequency of 121.5Mhz in VHF/ 243 Mhz UHF, should be capable of transmitting continuously for 48 hours.
  •  ELT is battery operated

 

 

GLOBAL POSITIONING SYSTEM:

  • GPS is a satellite based navigation system.
  •  GPS consists of three segments, they are
  1.  The space segment
  2.  The control segment
  3.  The user segment

 

  • GPS is capable of providing
  1.  Position in three dimension
  2.  Velocity determination
  3.  Time
  •  it works on the frequency of 42Mhz/ 1227.60Mhz

 

Basic principle of operation

  1.  GPS uses a similar principle of operation to radar
  2.  The satellite transmits a signal
  3.  The receiver measures the time the satellite signal is received
  4.  Knowing the time of transmission the time difference is measures and the range is calculated.

 

  • The space segment is made up of group of satellites known as “constellation”, which provides the navigational signals. It consists of
  1. Six orbits are used naming from a → f, with 4 satellite numbered from 1        → 4.
  2.  24 satellites, of which 21 is operational and 3 held in reserves.
  3. The orbits are synchronous and inclined at 55° to the equator.
  4.  Orbit height is about 20200Km vertical
  5.  Satellite takes 11hr 57min

 

  • The satellite receiver includes
  1.  Aerials, normally on the top of the aircraft fuselage
  1. Operating transmitter and receiver
  1. Quartz clock

 

  • The accuracy of the GPS is 0.003seconds every 1000 years
  •  GPS needs 3 satellites to locate a 2D fix/ 4 Satellites – 3D fix/ 5th satellite for RAIM

 

Navigation notes

Arunaksha Nandy

 

 

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