1. GPS and EGNOS in the EUR-SAM CORRIDOR
Lisardo Rodríguez Rabanal
División de Navegación por Satélite
Unidad EGNOS Torrejón

2. INDEX What is EGNOS? EGNOS ARCHITECTURE RNP FOR SBAS
EGNOS COVERAGE AREA
PERFORMANCES OVERVIEW
EGNOS INTEGRITY
CONCLUSIONS

3. WHAT IS EGNOS?
EGNOS (European Geostationary Navigation Overlay Service) is the European SBAS (Satellite Based Augmentation System) compliant with the OACI standard (Annex 10 of SARPS)
EGNOS uses the GPS and GLONASS constellations as well as additional geostationary satellites which signals are collected by a network of ground stations for generating the EGNOS navigation message

4. EGNOS ARCHITECTURE ( 2 INMARSAT III ( 2 INMARSAT III GPS GLONASS
+ 1 Artemis )
+ 1 Artemis )
Spatial Segment
GPS
GPS
GLONASS
GLONASS
User Segment
Ranging Integrity and Monitoring Stations
NLES
NLES
(dos por GEO)
RIMS1
RIMS1
RIMS2
RIMS2
RIMS 34
RIMS … n
Ground Segment
EGNOS Network (EWAN)
Red EGNOS (EWAN)
MCC1
MCC1
MCC2
MCC2
MCC3
MCC3
MCC4
MCC4
Mission Control Centres
PACF
PACF
ASQF
ASQF
DVP
DVP
Support Segment

5. RNP FOR SBAS (I)
ACCURACY difference between the estimated position and the actual position.
INTEGRITY is a measure of the trust which can be placed in the correctness of the information supplied by the system. Integrity includes the availability of the system to provide timely and valid warnings to the user (alerts) when the system must not be used for the intended operation.

6. RNP FOR SBAS (II)
CONTINUITY It is the probability that the system will function properly for the duration of the flight operation given that the system was functioning properly at the beginning of the operation.
AVAILABILITY The portion of time during which the system is to be used for navigation during which reliable navigation information is presented to the crew, autopilot or other system managing the flight of the aircraft.

7. RNP FOR SBAS (III)

8. EGNOS COVERAGE AREA
EGNOS shall provide down to and including RNP 0.3 in the joint union of the ECAC Flight Information Regions (FIR).
The shaded area comprises the footprint of all FIR of ECAC member States (including Canary Islands FIR) and the oceanic control areas of Reykjavik, Shanwick and Santa Maria.

9. PERFORMANCES OVERVIEW (GPS)

10. PERFORMANCES OVERVIEW (GPS)

11. PERFORMANCES OVERVIEW
The accuracy of GPS achieved in the Canary Islands is quite good.
As the Canary Islands are located in the border of the EGNOS service area (landmasses of the ECAC) the EGNOS accuracy will be quite similar to the GPS one.
The reason is that some satellites are discarded during the solution computation because of the lack of the ionospheric computation.

12. EGNOS IONOSPHERIC MODEL

13. SATELLITES USED vs. IN VIEW

14. EGNOS INTEGRITY
So the GPS/GLONASS performances in terms of accuracy could achieve the required performances for En-route, Terminal Area and Non-Precision Approach.
However GPS as standalone system does not reach the performances in terms of integrity, continuity and availability.
We need a measure of the trust which can be placed in the correctness of the navigation solution and timely alerts to the users when the navigation system must not be used for the intended operation.

15. EGNOS INTEGRITY
To ensure that the GNSS position error is acceptable an alert limit is defined that represents the largest position error which results in a safe operation.
At the same time EGNOS provides us the means to compute an estimation of the navigation error (Protection Level).
Position errors greater than the alarm limit must be indicated to the crew, otherwise integrity has failed and flight safety is at risk.
The GNSS integrity requirement is validated my means of measurements and simulations (due to the stringent probability 10-7) checking that the Navigation Error is bounded by the Protection Level.

16. EGNOS INTEGRITY (SIMULATIONS)
The next slides contain results obtained with the EGNOS End-To-End Simulator.
A constellation of 27 GPS satellites + 1 EGNOS GEO has been configured.
The EGNOS performances are evaluated in several airports in Canary Islands
The results allow us to obtain an overview of the accuracy and integrity achieved with EGNOS in the Canary Islands.

17. APV-I IN LANZAROTE

18. APV-I IN LANZAROTE

19. CONCLUSIONS Good GPS accuracy in the Canary Islands region
“When you get a GPS navigation signal, how do you know you can trust it?”
EGNOS will tell you whether you can trust the signal. It will tell you that you are at a particular spot with a high degree of certainty and definitely within an area enclosed by a circle with the spot at the centre. In effect, it will give you your position and say by how much it could be out.”

20. CONCLUSIONS
En-route phases of flight can also take advantage of the EGNOS Integrity, Continuity and Availability benefits
Operational EGNOS (Operational Validation, ATC interface, Procedures Design)

21. CONTACT DETAILS Lisardo Rodríguez Rabanal
Aena / Satellite Navigation Division
EGNOS UNIT
Phone: /06