1. Agenda Item 6
GNSS Operations Ross Bowie, NAV CANADA Rapporteur, Operational WG Navigation Systems Panel
Thank you…
Good morning…
I am ... and member of ATMCP.
The complete title of the presentation is: Need for the development of performance criteria and the concept of required total system performance (RTSP): It relates directly to the topics to be addressed under agenda item 3 of the Conference, but you will easily see connections with virtually all agenda items. Performance, including safety, provides a vehicle to discuss all aspects of Air Navigation from the planning stages to the monitoring of actual service delivery.

2. Outline Meeting performance requirements Basic GNSS operations
SBAS operations
GBAS operations
Implementation issues
GNSS evolution

3. 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

4. Achieving Performance (cont’d)
Continuity
- achievable via redundancy, demonstrated
Availability
- achievable, high availability challenging for the most demanding operations

5. 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

6. 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)

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

8. 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)

9. Performance Comparison
Horizontal & Vertical Integrity Alert Limits
LNAV/VNAV (H=556m) - SBAS* or (GPS + Baro VNAV)
*with V=50m
APV-I (H=40m, V=50m) - SBAS
APV-II (H=40m, V=20m) - SBAS
[Cat I (H=40m, V=12m ) - GBAS or future SBAS]

10. 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)

11. 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)

12. Implementation Issues (cont’d)
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

13. 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

14. 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

15. 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)

16. Summary Basic GNSS is in widespread use SBAS is being introduced
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