European Space Agency

GAMMA - GNSS for Airport Movements Monitoring and Alerting


The objective of the GAMMA project is to develop and demonstrate a pre-operational A-SMGCS which will provide surveillance and conflict detection services to controllers and vehicle drivers at airports. The GAMMA services will use EGNOS (and GALILIEO in the future) as enabling technology for mobiles localization with an adequate level of accuracy and integrity.

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GAMMA only addresses the A-SMGCS (Advanced Surface Movement Guidance and Control System) functions which are closed to operational exploitation and should provide more benefits by using GNSS: guidance, surveillance, control.


The Guidance Service displays the position of the vehicle on an airport map to the driver. This will reduce navigation errors which occur especially in conditions of reduced visibility.


The Surveillance Service displays the position and the identity of all mobiles moving at the airport to both the driver and the controller. It provides the awareness of all the ground traffic, allowing detection of any dangerous mobile which (s)he could not see visually.


The Control Service provides assistance to both the controllers and vehicle drivers by generating automatic alerts. An alert situation is, for example, a vehicle moving on the runway when an aircraft is taking-off or landing.


The approach contained in the GAMMA project is to consider that future A-SMGCS systems will be based on cooperative mobiles. This implies that all surface vehicles have to be equipped with a dedicated 'GNSS receiver'.


The A-SMGCS services are very critical in terms of performance. One of the main performance issues to be considered is the accuracy of the mobiles position. The position must be accurate enough in order to correctly detect the alert situations.


Use of EGNOS is of key importance to meet the accuracy and integrity requirements for vehicle location.


The 2 demonstrations have shown that EGNOS was able to provide the required accuracy for vehicle location. The accuracy was measured through the Horizontal Protection Level which is an upper boundary of the error on the position. Requirements on HPL values are the following ones:

  • Less than 7.5 meters for collision and infringement detection purposes,
  • And less than 12 meters for surveillance and guidance purposes.


GAMMA services were successfully validated with users: drivers and controllers. Operational trials stressed the need to update Airports' procedures to take into account the new information provided by such a system and to make a better use of it.


Services monitoring and the provision of integrity indication have largely contributed to confidence of the end users.


Users were also extremely confident about the benefits in terms of improvement of safety on airport but also in terms of a more efficient use of airport capacity. Moreover, the first comments they provided show their interest in such a system and will allow to improve it towards an operational system. A first set of « key performance indicators » for an operational system has already been defined.


GAMMA has experimented with a low-cost A-SMGCS based on GNSS to equip vehicles on the airport movement area and ATC systems. The main objectives of the project were reached and the relevance of the use of EGNOS for an A-SMGCS system has been demonstrated.


In order to provide the GAMMA services to the drivers, the vehicles must be equipped with an embedded system able to:

  • Retrieve the vehicle position given by GNSS,
  • Broadcast its position and identity to other mobiles,
  • Send the system status for system monitoring on the ground,
  • Receive information from the ground system (status of runways, alerts).

This implies that each vehicle will be equipped with a GNSS receiver and communication means.


With regard to the services provided to the controllers, a ground system is needed, including the controller working position (CWP), the modules for alert situation detection and system monitoring. This ground system will be connected to the communication networks in order to exchange data with the vehicles. Two communication networks are used:

  • An UHF network, in charge of broadcasting information about the operational context (traffic context): airport map, map's updates, current airport configuration, etc,
  • A VDL4 network, used to broadcast vehicles' positions.

The different elements of the ground system are connected to both communication networks ground stations:

  • ATC ground station (VDL-4),
  • Private Network ground station (UHF).

The ground system is composed of a Controller Working Position to provide the GAMMA services to the controller, and other modules:

  • Alert situation detection module,
  • System monitoring module,
  • Traffic generator for test.

The CWP will display to the controller:

  • Mobiles parameters (position + identity) provided either by the VDL-4 ground station or by a traffic generator for simulation purposes,
  • Alerts provided by the alert situation detection module,
  • Warning on the system status provided by the system monitoring module.

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The GAMMA project will be performed in two phases. Phase 1 will last about 5 months and Phase 2 about 16 months. Phase 1 has set the requirements and Phase 2 was focused on systems development and evaluation.

Phase 1 was composed of 3 tasks. The Requirements Assessment was a prerequisite for the Definition of GAMMA Demonstration System. Phase 1 ended with the planning of the field demonstrations.


The Phase 2 tasks have been sequenced in the following way:

  • Detailed Design,
  • Development,
  • Field Demonstrations,
  • Critical Assessment,
  • Final documentation.

Field demonstrations were conducted:

  • In Toulouse Blagnac Aiport (France) from September 2004 to December 2004,
  • In Fransisco Sa Carneiro Porto Airport (Portugal) from February 2005 to June 2005.

Following Porto demonstration, and taking into account the great amount of data and of experience that it provided, ANA, Porto Airport operation managers and M3 Systems have decided to continue the experimentation till December 2005.

Current status

Final presentation took place in ESA premises on September 13th 2005.


Porto demonstration has been extended in order to collect additional data on EGNOS signal and to start to work on a proposal for operational procedures update.

Status date

Tuesday, December 9, 2014 - 12:41