Galileo
and Aviation – Frequently asked questions
What are the Services
that will be offered?
What Infrastructure will
be deployed?
What is the role of EGNOS
in Galileo?
Will it be Interoperable
with GPS?
What can Galileo bring to
Civil Aviation?
What Standards will be
Required?
An Example of the
Potential Benefits of Satellite Navigation in Aviation
What is Galileo?
Galileo will be the European contribution to the
Global Navigation Satellite System (GNSS). Based on the same technological principles as the American GPS
and the Russian GLONASS system, Galileo presents a major advance in satellite
navigation technology: It is the first such system being specifically designed
for civil and commercial purposes and will be state-of-the-art, highly
efficient and reliable.
Galileo is designed to be interoperable with the other radio-navigation
systems. This will be
beneficial to all users as they will be able to use more satellites for
redundancy and higher accuracy.
How much will it cost?
Galileo
is vital for the future of Europe’s high‑technology industries. It will
generate new, large markets and provide the critical advance in technology for
Europe to be a global competitor. While the cost of deploying the system is
some EUR 3.9 billion (in net present value terms, over 20 years), its
expected macro-economic benefits have been estimated at some EUR 17 billion,
leading to a high benefit to cost ratio. The expected jobs creation profile is
to be counted in tens of thousands with an equipment and services market of
some EUR 10 billion per annum by 2010.
Artist’s view of a Galileo satellite. © ESA,
J. Huart
What are the Services that will be offered?
Four distinct
navigation services and one service to support Search and Rescue operations
have been identified to cover the widest range of
users needs, including those of professional users, scientists, mass-market
users, safety of life and public regulated domains. The Galileo
satellite-only services can be enhanced on a local basis through local elements
for applications with more demanding requirements and depending on specific
environmental characteristics.
The Open
Service (OS) results from a combination of openly available signals. This
service is free of user charges and provides position and timing performances
comparable with other GNSS systems. The Safety of Life Service (SoL) improves
the open service performance by providing timely warnings to the user when it
cannot guarantee to meet certain margins of accuracy (integrity). It is
envisaged that a service guarantee will be provided for this service. The
Commercial Service (CS) provides access to two additional signals to allow for
a higher data rate throughput and to offer a higher accuracy to users. It is
envisaged that a service guarantee will be provided for this service. The
Public Regulated Service (PRS) provides position and timing to specific users
requiring a high continuity of service, with controlled access. Two PRS
navigation signals with encrypted ranging codes and data will be available. The
Search and Rescue Service (SAR) broadcasts globally the alert messages received
from distress emitting beacons. It will contribute to the enhancement of the
performances of the international COSPAS-SARSAT Search and Rescue system.
|
Galileo Services |
Open Service
|
Commercial
Service |
Public Regulated Service |
Safety-of-Life Service |
||
|
Coverage |
Global |
Global |
Local |
Local |
Global |
Global |
|
Accuracy |
15-30 m (single
frequency) 5-10 m (dual
frequency) |
5-10 m (dual frequency) |
<10 cm – 1 m (local augmentation signals) |
1 m (local augmentation signals) |
4-6 m (dual
frequency) |
4-6 m (dual
frequency) |
|
Availability |
99% |
99% |
99% |
99-99.9% |
99-99.9% |
99% - 99.9% |
|
Integrity |
Not
generally required |
Value-added
services |
Mandatory
requirement |
Yes |
||
|
Alert Limit |
- |
20-45 m |
2-3 m |
3-5 m |
<15 m |
12-20 m |
|
Time to Alert |
- |
10 s |
1 s |
1 s |
6 s |
6 s |
|
Integrity Risk |
- |
2x10-7/hour |
2x10-7/hour |
2x10-9/150
s |
3.5x10-7/150
s |
2x10-9/150
s |
|
Continuity Risk |
- |
10-4/hour |
10-4/hour |
< 10-5/15
s |
< 10-5/15
s |
8x10-6/15
s |
|
Certification and Service Guarantees |
No |
Guarantee of
service possible |
Build for
certification, guarantee of service possible |
Yes |
||
What Infrastructure will be deployed?
The core of the Galileo system will be the global constellation of 30 satellites in three Medium Earth orbital planes inclined at 56˚ to the equator at about 23.000 km altitude. Ten satellites will be spread evenly around each plane with each taking about 14 hours to orbit the Earth. Each plane will have one active spare able to cover for any failed satellite in that plane. An inter-connected ground infrastructure will complete the system. The Ground infrastructure will mainly consist of 2 Galileo Control Centres, 5 Monitoring and Control Stations and 5 Mission data up-link Stations which will allow a global coverage without interruption. Regional components will independently provide the integrity of the Galileo services by means of additional facilities. Regional service providers using authorised integrity uplink channels provided by Galileo will disseminate regional integrity data. Local components will enhance the above with local data distribution by means of terrestrial radio links or existing communication networks in order to provide additional accuracy, availability and integrity for critical applications.
Artist’s view of the Galileo
constellation. © ESA, J. Huart
|
When will it be Available?
The
Galileo infrastructure will be implemented in three phases. During the
Development and Validation phase (2002-2005), the mission requirements will be
consolidated, the satellites and ground-based components developed and the
system validated in orbit. During the Deployment phase (2006-2007), the
construction and launch of the remaining satellites will occur and the complete
ground segment will be installed. The final, Operations, phase is expected to
begin in 2008. The Development and Validation phase will be co-funded by the
European Space Agency and by the European Commission. Additional funding will
come from Research and Development Programmes. The supervision of the
development and validation phase and the preparation of the deployment and
operational phase will be the main tasks of a new structure, the Joint
Undertaking (JU) founded by the European Community and the European Space
Agency. The JU will last four years and be based in Brussels. The technical
implementation of the development and validation phase is entrusted to the
European Space Agency through an agreement between the JU and ESA. The
development and validation phase comprises the launch of an experimental
satellite followed by a first series of satellites. This will help finalise
technological developments and ensure the large-scale demonstration of the
capabilities and performance of the system. The JU will also oversee the optimal
integration of EGNOS into Galileo and will launch research and development
activities in co-ordination with national activities in this area.
What is the role of EGNOS in Galileo?
The
European Geostationary Navigation Overlay Service (EGNOS) is Europe’s first
entry into satellite navigation. It is being developed by ESA under a
tripartite agreement between the EC, Eurocontrol and ESA. Several air
navigation service providers are supporting the development programme with
their own investments. EGNOS will complement the military-controlled GPS and
Glonass systems. It will disseminate integrity signals on the GPS L1 frequency
giving real-time information on the health of the GPS and GLONASS
constellations. Correction data will improve the accuracy of the current
services from about 20 m to better than 5 m. The EGNOS coverage area includes
all European states and could be readily extended to include other regions
within the coverage of the two INMARSAT geostationary satellites being used.
EGNOS is one of the three inter-regional, interoperable satellite-based
augmentation services (the other two are the US WAAS and the Japanese MSAS).
EGNOS will be the first stimulus for European-led
navigation services and will as such pave the way for the Galileo services. For
civil aviation use, EGNOS complies with ICAO global standards. It is also
expected to cover multi-modal transport and many other non-transport
applications. An EGNOS System Test Bed (ESTB) broadcasting an EGNOS test signal
has been available since early 2000. The ESTB provides an opportunity to
develop and validate new applications in a realistic environment
From early 2004, EGNOS will provide a guaranteed
GPS/GLONASS integrity service using the infrastructure and space segment as
currently planned. EGNOS will be integrated into Galileo to allow a
common full-scale satellite navigation service for all kind of users. Any
evolution of the GPS integrity service will be taken into consideration.
Will it be Interoperable with GPS?
Galileo
is being designed as an independent satellite navigation system but, at the
same time, this design is optimised for use with other systems, notably GPS.
Key drivers for facilitating the use of Galileo with other systems are user
requirements and the objective of gaining access to future GNSS markets. Three
main interoperability objectives have been identified. The first objective to
ensure the interoperability of Galileo with other GNSS systems (mainly GPS)is
at the receiver level. This is reflected in the study and choice of
frequencies, signal structure, time reference frame, and geodetic datum. In
addition, interoperability issues lie in the combined use of Galileo with other
non-GNSS systems such as ground navigation systems or mobile communication
networks to enable a reduction of GNSS deficiencies through the provision of
combined positioning services. Another objective is to facilitate the use of
Galileo with telecommunication systems to provide joint
navigation/communication services. This is an additional functionality that
enables enhanced communications capabilities (e.g. higher data transfer) and
facilitates the generation of GNSS value-added services such as location-based
services with a strong influence in the future GNSS market. The combined use of
Galileo with all these systems will introduce interoperability requirements,
not only in the Galileo global components, but also in the design of local
components and user equipment.
What can Galileo bring to Civil Aviation?
The
operations of many airspace users are, by their nature, global. The aviation community requires world-wide
systems that provide safe and efficient services, are compatible and
interoperable and do not require different avionics.
The
general objective of the global ICAO CNS/ATM Concept and System is to give to
aircraft operators the freedom to dynamically follow preferred flight profiles
with a minimum of constraints, while also maintaining or increasing the actual
level of safety. Such a system, if
successfully completed and implemented, will give a new perspective to the
airborne and ground components of the CNS/ATM systems. A GNSS, providing a
robust global area navigation capability, will be an important enabler of the
global ICAO CNS/ATM Concept.
In
the context of Galileo Euocontrol has co-ordinated the development of a common
aviation position paper on GNSS which has been prepared with the participation
of Airspace Users and Air Navigation Service Providers. The main goal expressed in this paper is as
follows:
If world-wide GNSS is the most cost beneficial solution, and
is supported by a successful safety analysis, it should become the “sole
service” navigation system, for provision of positioning and timing data, for
all phases of flight.
The term “sole service” does not imply that the GNSS should
be the only navigation capability available onboard the aircraft but it is used
here to refer to the only radio-navigation service provided external to the
aircraft. Aircraft might also require
onboard inertial systems in order to meet the required navigation
performance.
In order to achieve this goal, there is a clear need for a
worldwide Navigation Strategy, not only a European Navigation Strategy. All
Strategies should be developed under the auspices of ICAO and be supported by
all the key partners. Such a world-wide
Strategy should address:
1) Sole
service concept feasibility regarding safety requirements
2) Technical, Operational and Safety requirements, calling
for the development of a world-wide Navigation Satellite System that can be
used, as the sole-service for provision of positioning and timing data, for all
phases of flight down to CAT II/III operations. Due consideration must be taken
of regional and sub-regional specific requirements; and global interoperability
and complementarity must be ensured.
3)
Institutional Requirements calling for world-wide resolution of institutional
issues and guarantees from the GNSS Service Providers
4) Cost
allocation and Charging Requirements, calling for fair and equitable charging
and cost-allocation between civil aviation and other user categories, between
States and between phases of flight (en-route vs. approach/aerodrome);
5) Transition Planning, calling for commitment for
decommissioning of ground based navigation aids, giving due consideration to
Global Equipage Implications and calling for Commitment from Users to equipage
with appropriate GNSS avionics and calling for the establishment of an
Implementation Plan.
The aviation
community has generally welcomed the Galileo development but is cautious as the
costs and benefits have not been studied yet.
Galileo cannot be considered in isolation. Any assessment of navigation
needs must take account of the existing infrastructure and alternative means of
meeting the navigation performance requirements. The combination of an improved GPS and Galileo will provide a
very robust navigation capability. If
Galileo is designed to be sufficiently different from GPS to avoid common modes
of failure then it may be possible to remove some, if not all, of the existing
navigation infrastructure.
What Standards will be Required?
The
International Civil Aviation Organization (ICAO) has been working on GNSS
standards over the last few years to speed up the operational introduction of
GNSS for civil aviation. In particular, the GNSS panel (GNSSP) has developed
standards and recommended practices for existing GNSS core constellations (GPS
and GLONASS) and two different kinds of augmentations (Satellite Based
Augmentation Systems like EGNOS and Ground Based Augmentation Systems) that
provide additional benefits to the community for regional and local operations
that require performance levels not achievable by GPS or GLONASS alone. These
standards, after thorough validation activities, were published in November
2001 as part of Annex 10 to the Chicago convention.
In
parallel, work has been on-going to deal with many other operational issues
linked to the introduction of GNSS. An ICAO manual was prepared by GNSSP that
provides guidance to States that want to authorize operations supported by GNSS
. A NOTAM scheme was also designed that takes into account the specificities of
satellite navigation systems that provide a global service with performance
varying geographically and over time. Finally, the Obstacle Clearance Panel
(OCP) has also been working to define procedure design criteria for different
kinds of operations based on stand-alone or augmented GNSS.
These
different activities pave the way for a smooth and early transition to GNSS for
different operations depending on the airspace complexity and traffic density.
With
regards to GALILEO, work has already
started within the GNSS Panel to prepare the future of standards. The initial work, supported by the European
Commission and the European Space Agency, consisted in providing detailed
technical information on the GALILEO services and system baseline in order to
collect feed-back from the aviation community on desirable features for the
GALILEO system. The work is now continuing, and standard development is on the
work program of GNSSP for its 5th formal session to be held in 2005.
Finally,
a global Air Navigation Conference will be held in Sept 2003, during which the
overall ICAO strategy for the transition to GNSS will be re-assessed. In
particular, one key aspect to be discussed during the conference is the
vulnerability of existing single frequency systems and the potential benefits
that could be expected from the use of several independent satellite
constellations, each of which providing two or three frequencies. In this
perspective, the introduction of GALILEO should significantly alleviate
interference issues in the future operational environment.
An Example of the Potential Benefits of Satellite Navigation in Aviation
In
September 2001 Eurocontrol conducted a flight experiment at Nice/ France to
demonstrate how the improved navigation performance made available by EGNOS
could facilitate curved approach procedures improving safety and reducing
aircraft noise for local residents.
Aircraft approaching Nice today in low visibility conditions must use
the instrument landing system which brings them directly over the Cap d’Antibes
and over many homes. In good visibility
there is a manual procedure that can be flown around the peninsula avoiding the
environmental problem.
An
experimental procedure was designed by the French DGAC specifically for the
trials based on the visual procedure but assuming that the aircraft is capable
of following a precise 3-dimensional trajectory with a high accuracy. Such a procedure could be flown in low
visibility conditions thus removing the need to fly over residential
areas.
The
Nice trial demonstrated that such curved approach procedures would be enabled
by the provision of navigation performance available from GNSS and the area
navigation capabilities of modern aircraft.
With the introduction of Galileo such procedures could be envisaged at
many locations throughout Europe providing environmental improvements for local
inhabitants.
Figure 1 Experimental Approach
Procedure to Nice
Conclusions
GNSS operations will become the enabler for advanced air
traffic control around the globe. Many manoeuvres and procedures will only
become reality with a reliable and safe GNSS. GALILEO will be a key element of
this future GNSS as it will provide the aviation community with an independent
additional satellite navigation source on multiple frequencies. This will
significantly reduce the potential vulnerability of the current GNSS components
in most phases of flights. The design of GALILEO fully takes into account the
aviation community requirements for a future GNSS and will provide a highly
accurate and reliable navigation signal easily accessible for the aviation
users. The integrity service of the GALILEO system will be accessible
world-wide to guarantee the service with special focus on the aviation
community.
It can be expected that with the variety of independent GNSS
constellations to which GALILEO will contribute aviation will be in a position
to take for the first time full advantage of a GNSS, which is at the same time
safe, accurate, reliable and cost effective.
More information
European
Commission Galileo Web Site
European
Space Agency Navigation Page
Eurocontrol Trials with the
EGNOS Test-Bed
or contact:
GNSS Project Leader
Tel: +33
(0) 1 69 88 7651
Fax: +33
(0) 1 69 88 7307