- Navigation = Knowing your current position, your destination, and estimating time/fuel to get there.
- Purpose: Safe and efficient aircraft movement through airspace.
Definition of Navigation
Navigation Methods
- Pilotage: Visual reference to landmarks
- Dead Reckoning: Based on speed, direction, and time
- Celestial Navigation: Using stars, moon, sun (almanac)
- Radio Navigation: Ground-based radio signals
- Space-Based Navigation: GNSS (GPS, Galileo, etc.)
The Earth & Reference Systems
- True North vs Magnetic North (declination/variation)
- Latitude: North/South
- Longitude: East/West
- Geoid: Mean sea level surface
- Ellipsoid: Mathematical model of Earth
- Altitude: Height above sea level
- Flight Level (FL): Pressure-based reference (1013.25 hPa)
Magnetic Field & Interference
- Magnetic variation affects compass readings
- Lightning and electromagnetic emissions cause interference
- GPS signals can be jammed or spoofed
Navigation Equipment
- Maps: ICAO charts, Jeppesen, Lido
- Compass: Magnetic (whiskey compass)
- Gyro / IRS: Measures rotation and acceleration
- Barometric Altimeter: Pressure-based
- Radar Altimeter: Measures height above terrain (4.3 GHz, affected by 5G)
- FMS: Flight Management System
- Cockpit Instruments: Conventional (Seneca) and digital (A220)
Conventional Radio Navigation Aids
NDB (Non-Directional Beacon)
- LF/MF band (190–1750 kHz)
- Omni-directional signal
- Requires ADF (Automatic Direction Finder)
- Accuracy: ±3° to ±10°
- Mostly decommissioned
VOR (VHF Omni-directional Range)
- VHF band (108–117.95 MHz)
- Provides bearing info
- Types: C-VOR (conventional), D-VOR (doppler)
- Accuracy: ±1.5° to ±5°
- Used for en-route and non-precision approaches
DME (Distance Measuring Equipment)
- Measures slant range
- Paired with VOR or ILS
- Accuracy: ±0.1–0.2 NM
- Used for approach and en-route
ILS (Instrument Landing System)
- Localizer (LOC): Horizontal guidance (108–112 MHz)
- Glide Path (GP): Vertical guidance (328.6–335.4 MHz)
- Categories: CAT I, II, III
- Used for precision approaches
Space-Based Navigation (GNSS)
GNSS Architecture
- Space Segment: Satellites
- Control Segment: Ground stations
- User Segment: Aircraft receivers
GNSS Constellations
- GPS (USA): 24+ satellites, L1/L2/L5, WGS-84
- GLONASS (Russia): G1/G2, PZ90
- Galileo (EU): 30 satellites, GTRF, high accuracy
- BeiDou (China): GEO, MEO, IGSO
- RNSS: Regional systems (QZSS, IRNSS)
GNSS Limitations
- Single frequency
- Weak signal
- Jamming & spoofing
- No built-in integrity
GNSS Augmentation Systems
ABAS (Aircraft-Based)
- RAIM: Receiver Autonomous Integrity Monitoring
- AAIM: Uses INS, barometric altimeter
GBAS (Ground-Based)
- Differential GPS corrections via VHF
- Used for CAT-I precision approaches
- GLS (GBAS Landing System)
SBAS (Satellite-Based)
- Wide-area corrections via geostationary satellites
- Examples:
- EGNOS (Europe)
- WAAS (USA)
- MSAS (Japan)
- GAGAN (India)
Performance Parameters
- Accuracy: Closeness to true position (95%)
- Precision: Repeatability
- Integrity: Trustworthiness + alerting
- Availability: % of time usable
- Continuity: No interruption during operation
- Coverage: Area of service
Performance-Based Navigation (PBN)
Concept
- Navigation based on performance, not equipment
- Defined by:
- Navigation Application
- Navigation Specification
- Navigation Infrastructure
Navigation Specifications
- RNAV 5: En-route, ±5 NM (mandatory in Switzerland)
- RNAV 1: SID/STAR, ±1 NM
- RNP 1: SID/STAR with onboard monitoring
- RNP APCH: GNSS-based approach
- RNP AR APCH: Curved approach, authorization required
- RNP 0.3: Advanced helicopter ops
Regulations
- ICAO Doc 9613 (PBN Manual)
- EU 2018/1048: RNAV/RNP implementation
- EU 716/2014: Free Route Airspace above FL310
Future Developments
- RNP 4: Oceanic
- RNP 2: Continental en-route
- Multi-frequency GNSS
- LEO-PNT: Low Earth Orbit navigation
- eDME, LDACS-NAV, Mode N
