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

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

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

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

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.

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.

RNP FOR SBAS (III)

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.

PERFORMANCES OVERVIEW (GPS)

PERFORMANCES OVERVIEW (GPS)

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.

EGNOS IONOSPHERIC MODEL

SATELLITES USED vs. IN VIEW

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.

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.

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.

APV-I IN LANZAROTE

APV-I IN LANZAROTE

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.”

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)

CONTACT DETAILS Lisardo Rodríguez Rabanal Aena / Satellite Navigation Division EGNOS UNIT Phone: 91 678 54 00/06 e-mail: lisardor@aena.es jacuadron@aena.es