ATA 34: Airbus A320 (Technical Notes)

ATA 34 – NAVIGATION

• Air Data/Inertial Reference System (ADIRS)
• Landing and taxing aids
• Independent position determining
• Dependent position determining

ADIRS

• 3 Air Data/Inertial Reference Units (ADIRU) > ADIRU 1, ADIRU 2, ADIRU 3.
  • Air data function through its Air Data Reference (ADR) portion.
  • Attitude, heading and position function through its Inertial Reference (IR) portion.
• Standby systems
  • ISIS
    • ISIS indicator replaces 3 conventional standby instruments –
    • Standby altimeter
    • Standby airspeed indicator
    • Standby horizon indicator
  • Standby Compass – for standby heading ……… (independent instrument)

Landing and Taxiing Aids

• Paravisual Indicator (PVI) (optional system)
• Head Up Display (HUD) (optional system)
• Instrument Landing System (ILS) (optional system)  >>> MMR
  • The primary function of the Multi-Mode Receiver (MMR) is to receive and process Instrument Landing System (ILS) and Global Positioning System (GPS) signals.
  • The MMR also receives the approach data from the Global Navigation Satellite System (GNSS) Landing System (GLS) function.
  • The MMR is a navigation sensor with two internal receivers – ILS receiver & GPS receiver. >> (ILS receiver – Localizer and Glide/slope).
  • 2 MMRs – MMR1 and MMR2, linked to:
    • Localizer and Glide/slope antenna
    • GPS antenna

Independent Position Determining

• Weather Radar (WXR) system
• Radio Altimeter (RA)
• TAWS – Generic Term
  • Ground Proximity Warning System (GPWS)
  • EGPWS
• TACS – Generic Term
  • Traffic Alert and Collision Avoidance System (TCAS)
  • Traffic and Terrain Collision Avoidance System (T2CAS)
  • Traffic and Terrain Collision Avoidance System (T3CAS)

Dependent Position Determining

• Distance Measuring Equipment (DME)
• Air Traffic Control (ATC)
• Automatic Direction Finder (ADF)
• VHF Omni-Range (VOR)
• Global Positioning System (GPS) (optional system)

Training Note

• Why pitot/static port both side (cross connection) – to minimize error.
  • Static – position error
• Total 8 ADM – all are interchangeable
• Pitot – 3
• Static – 6
• Pitot probe – total pressure
• ISIS – direct connection to port not through ADM
  • Source – pitot – stby pitot probe / static – stby static probe
• Laser gyro – total 3 – inside ADIRU (IR part).
  • 2 beam in each gyro – beam travel time
  • Error signal in terms of frequency
  • Frequency is inversely proportional to time.
• IR inside
  • 1 ring laser gyro for each axis
  • 1 accelerometer for each axis
• There is a separate 3 axis accelerometer for FDR. (do not confuse with accelerometer inside IR)
• Water drain in stby static port – because direct source for ISIS.
• Mode selector unit (MSU) of ADIRS (- ADIRS MODE)
  • NAV
  • ATT – only heading
• ISIS
  • ATT/SPEED/ALT – Same place as in PFD.
• BUGS + LS – press for at least 2 sec. >> maintenance mode.
• LS – press to avail localizer and glidescope.
• BUGS – for BUGS setting. Press bugs only.
• Red flag – if system is inop. (eg. ATT , HDG in red)
• Mean sea level – for altitude calculation
• QNH – sea level atmospheric pressure
• In NEO only – ISIS test can be done through MCDU.
• GPS – 360 degree – divided into 6 >> each 60 degree
• When GPS is active – no VOR/DME/ADF is required.
• VOR/DME – single unit
• All DME are installed with VOR at ground >> VOR + DME – all VOR station
• If tune VOR – automatically tune DME, frequency are paired and installed at ground together.
• VOR/DME on ND
  • VOR 2 – VOR sys 2
  • VIDP – Airport
  • 34 NM – given by DME
• Minimum 4 satellite – GPS position (normally 6 are available)
• MMR – 90 VU
• ILS 1 – PFD 1 & ND 2
• ILS 2 – PFD 2 & ND 1
• GPS is primary navigation now.
• GPS Monitor Page on MCDU
  • MERIT – 100 >> GPS accuracy is up to 100 meter
  • mode/set
  • NAV/6 – 6 satellite
  • TRK – heading
• TAT 1 – only ADIRU 3. — stby
• ADIRU 1 — TAT 1.
• Normal
  • MMR 1 – ADIRU 1, 3 – GPS 1
  • MMR 2 – ADIRU 2 – GPS 2
• If ADIRU 2 fails –
  • ADIRU 2 >> ADIRU 3
  • Switch for GPS 2 input
    • ATT heading selector knob switching (?)
• FMGC
  • IR 1 & IR 2 – pure data – FMGC 1 & 2
  • Pure GPS data – FMGC 1 & 2
• MMR > GPS data > ADIRU > FMGC
• Weather radar transmitter with predictive windshear system function in option.
• In old a/c – Map mode – map selection >>>> in WXR system
  • Ground picture (antenna will tilt down)
  • Now – EGPWS is doing the same function.
• PWS – 5 NM (class range) – takeoff/landing
• Precipitation rate –
  • > 50 mm/hr – turbulence
  • 12 – 50 mm/hr
• Windshear indication on ND – Red & Black + warning on PFD
• CAL knob – minimum position, use for testing.
• WXR antenna
  • Holes for passing magnetic field
  • Waveguide – hollow tube – less distance required for waveguide, that’s why separate self in 90 VU.
  • Optical cable required less distance.
• Multiscan – top/down & left/right
• WXR related indication  – ND only
• PWS related indication – ND + meaning (details) > on PFD
• Aft side of WXR antenna – BOARD – for protection from return waves.
• WXR stabilization signal from – ADIRU 1
• PWS
  • below 2300 feet RA.
  • Aural warning through – FWC (windshear ahead)
• If warning for the same time – PWS / TCAS & EGPWS >> PWS warning is inhibited.
• RA auto ON – no switch
• RTTR
• RA indication on PFD.
• Cooling fan – 2 for 2 RA transmitter
• TA / RA advisory
  • 4 volume
  • Indication on ND
• GPWS – database updated at every defined time.
• GPWS system has no antenna. It takes data from sources and computes.
• ELS >> ADS-B (is enhanced version) >>> ADS-B – IN/OUT
• Many Airlines have ADS-B — OUT only.