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Advanced
Instruments (Inertial Navigation System (INS) - Ch 01 (INS…
Advanced
Instruments
Autoland - CH12
Requirements
- At least 2 A/Ps
- At least 2 Rad Alts
- Airport must have accurate and correctly calibrated radio aids AND ILS calibrated for autoland
- Both pilots must be LVO (Low viz ops) qualified
-- LVO airport procedures:
- Ground vehicle movements strictly controlled interfering the ILS sensitive area
- AC held further back at CAT III holds
- Crew must not call ‘RUNWAY VACATED’ til whole AC fully clear
LVO Categories
CAT 1
- A DH >200ft RVR >550m
- Only continue from DH if AT LEAST one of:
- See at least 3 consecutive lights of the centreline of the approach lights, or
- Touch down zone (TDZ) lights , centre lights (CL) or runway (R) lights
- A combination of the above
CAT II
- A DH below 200ft but >100ft and RVR > 300m
- Only continue from DH if AT LEAST one of:
CAT III
- CAT IIIA: DH lower than 100ft (usually 50ft) and an RVR not less than 200m
*CAT IIIB: DH lower than 100ft or no DH and an RVR not less than 200m but not less than 75m
CAT IIIA: No DH. Precision approach, landing and taxi possible
Alert Height
- Alert height is a height above the ground used as a decision point in the event of a system failure.
- Any failure above alert height which prevents an autoland, requires a decision either to go-around or to revert to a higher decision height. If viz references acheived a manual landing can be flown (CAT 1 reversion). If not, the crew must initiate a go-around.
Autoland system Redundancy
- Fail passive (Fail soft)
- If 1 AP fails below Alert Height, there is no deviation from flight path BUT AUTOLAND NOT POSSIBLE
- PFD annunciates SINGLE CH
- Fail operational (Fail Active) - 3 APs or 2APs and an extra control channel
- If 1 AP fails, AUTOLAND still possible cos still have 2 APs (or 1 AP and extra channel)
- After fail system downgrades to FAIL PASSIVE
- PFD annunciates LAND3 > LAND2 (when 1 AP fail) > NO AUTOLAND (sys. broken)
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GPWS/TAWS
- Basic GPWS cannot look ahead for terrain (rad Alt)
- Enhanced GPWS (EGPWS)/Terrain Avoidance Waring System (TAWS) has ability to predict the terrain ahead using a 3D database
TAWS (Terrain Avoidance Warning Sys
- Forward looking Terrain Avoidance (FLTA) with suitable visual and aural alerts
- Premature Descent Alert PDS) with suitable visual and aural alerts
- Sys is active between 50ft RA and 2450ft RA
- Inputs: RadAlt, Airspeed, Baro Alt, AC Config, ILS G/S, terrain DB
- Class A Turbine (Terrain info on ND)
- Excessive RoD
- Excessive closure rate wrt terrain
- Descent/Alt Loss after T/O
- Flight to terrain w/o landing config
- Down deviation from ILS/MLS Glideslope
- Call out '500'
- Class B Piston >5700kg or 9+ pax
- Excessive RoD
- Descent/Alt Loss after T/O
- Call out '500'
- Aural and visual alerts and warnings
- Controls: Flap inhibit, Gear inhibit, Terrain inhibit
- Alert (Amber) -> Warning (Red) = fly max AoC to MSA
- Classified: Genuine, Nuisance, False
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Terrain Awareness and Predictive Warning Mode
- Terrain data displayed in MAP or MAP CTR modes
- Terrain >2000 ft higher= red.
- Terrain 2000 to AC then 500ft below = amber.
- Terrain from 500-2000 ft below = Green
- Density of color Increases with terrain height
Look ahead Terrain Warnings
- 40-60 secs before impact: amber ‘CAUTION TERRAIN’ plus ‘AMBER TERRAIN(PFD)
- 20-30 secs before impact ‘ TERRAIN TERRAIN PULL UP’ plus (red)PULL UP (PFD)
Misc
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- Power = Torque * RPM
- CDEAD : Capacitiance (farrads) = DiElectric Permittivity * Area / Distance between 2 plates
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