GNSS Operations Ross Bowie, NAV CANADA Rapporteur, Operational WG Navigation Systems Panel

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GNSS Operations Ross Bowie, NAV
CANADARapporteur, Operational WGNavigation
Systems Panel
Agenda Item 6
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Outline

• Meeting performance requirements
• Basic GNSS operations
• SBAS operations
• GBAS operations
• Implementation issues
• GNSS evolution

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Achieving Performance

• Accuracy
• - easily achievable, demonstrated for Cat III
• Integrity (alert limits match operation)
• - achievable, demonstrated for APV
• - precision approach levels challenging
• - conservative integrity design decreases
  availability

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Achieving Performance (contd)

• Continuity
• - achievable via redundancy, demonstrated
• Availability
• - achievable, high availability challenging for
  the most demanding operations

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Basic GNSS Operations

• GPS and Basic GNSS receiver
• fault detection (RAIM)
• en-route and terminal RNAV
• RNAV non-precision approach (lateral guidance
  only)
• RAIM requires extra satellites in view
• need to retain ground aids and avionics
• RAIM prediction NOTAMs

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SBAS Operations

• Core satellite constellation(s), geostationary
  satellites, ground network, SBAS receiver
• SBAS receiver uses fault detection and exclusion
  in absence of SBAS signal
• High availability of integrity for en route,
  terminal, non-precision approach and approach
  with vertical guidance (APV)

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SBAS Implementation

• SBAS status (IPs/17,32,50,58)
• WAAS (USA) commissioned July 2003
• EGNOS (Europe), MSAS (Japan) to be commissioned
  2004-2005
• GAGAN (India) under development, 2005-2006
• States to ensure data integrity for SBAS
  approaches

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SBAS-based APV

• APV compared with non-precision approach
• vertical guidance stabilized descent
  integrity
• no need for guidance system at airport
• APV compared with Cat I precision approach
• lateral approach design identical
• vertical design slightly more restrictive
• lowest Decision Altitude 75m (250 ft)
• less ground infrastructure required (e.g.
  lighting)

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Performance Comparison
Horizontal Vertical Integrity Alert Limits
LNAV/VNAV (H556m) - SBAS or (GPS Baro
VNAV) with V50m
APV-I (H40m, V50m) - SBAS
APV-II (H40m, V20m) - SBAS
Cat I (H40m, V12m ) - GBAS or future SBAS
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GBAS Status Operations

• Core satellite constellations, ground station at
  airport, VHF datalink, GBAS receiver
• GBAS functionality in multi-mode receiver (MMR)
• Precision approach capability
• Cat I GBAS planned for 2006 (IP/16)
• Cat II/III issues studied (WP/20)

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Implementation Issues

• GNSS Manual (IP/14) provides guidance on
  implementation aspects
• Planning Organization
• GNSS implementation team
• Procedures development
• design criteria flight inspection
• Airspace considerations (RNAV operations)

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Implementation Issues (contd)

• Aeronautical Information Services
• surveys (WGS-84) and database
• GNSS status monitoring and NOTAMs (IP/71)
• Certification operational approvals
• system safety analysis
• spectrum protection (unintentional interference)
• avionics certification integration

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GNSS Vulnerability (WP/17)

• Signal interference issues
• good control of the electromagnetic spectrum to
  reduce the risk of unintentional interference
• intentional interference is the key concern
• threat analysis required for airspace concerned

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Mitigation Techniques

• To account for likelihood and impact of outage
• To ensure safety and reduce economic impact (not
  worth interfering)
• Suitable combination of
• integrated on board systems (inertial)
• pilot and ATC procedures (radar/non-radar)
• back-up terrestrial navaids where necessary
• DME to support RNAV
• strategically located ILS to support landing

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Future operational enhancements

• GBAS for Cat II/III approach surface operations
• Next generation satellite constellations
• Galileo, GPS III, GLONASS-K
• better resistance to interference
• improved performance (Cat I SBAS likely)
• reduced complexity of augmentations
• Optimum combinations of elements signals to be
  established (WP/18)

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Summary

• Basic GNSS is in widespread use
• RNAV and better non-precision approaches
• SBAS is being introduced
• APV, increased availability, reduced need for
  ground aids
• GNSS evolution
• operational enhancements when new signals
  available and fleets equipped
• take advantage of GNSS now, monitor future
  developments and plan accordingly