Mode S Monitoring Project

Introduction
What is Mode S?
Elementary and Enhanced Surveillance
The need for Mode S
Objectives of the Mode S Monitoring Project
Tasks
Aircraft Detection Monitoring Tools
Test Bench for Transponder Testing
Tools for Airborne Monitoring: ARTAS and BDAMS
Location of Tools and States Facilities
Reporting
Transponder Reporting
Airborne Reporting
Links
Contacts

Introduction

What is Mode S?

Mode S is based on a logical development of the Secondary Surveillance Radar (SSR) system currently deployed throughout the whole ECAC area in accordance with the ECAC En-Route Strategy for the 1990's. In addition to SSR functionality, Mode S enables the selective interrogation of aircraft and the extraction of air derived data through which new ATM functionality can be developed. Mode S standards are defined in ICAO Annex 10 Volumes III and IV amendment 73.

Mode S Elementary Surveillance will initially be introduced in the airspace of Belgium, France, Germany, Luxembourg, Netherlands and Switzerland. These Member States mandate the carriage and operation of Mode S Elementary Surveillance airborne equipment for all aircraft flying as GAT with effect from 31 March 2005.

The 3 main States implementing Enhanced Surveillance, France, Germany and the United Kingdom have harmonised their implementation plans and the supporting regulatory approaches. The Enhanced Surveillance Master Plan reflects this agreement and can be downloaded from Eurocontrol website:

http://www.eurocontrol.int/mode_s

Mode S (Select) is a co-operative surveillance technique for air traffic control and has been standardised by ICAO for many years.

It employs ground based sensors and airborne transponders. Mode S operates on the same Radio Frequencies (1030-1090MHz) as conventional SSR Systems.

Elementary and Enhanced Surveillance

Mode S Elementary Surveillance enables the use of the unique 24 bit aircraft address for selective interrogation and to acquire the Aircraft Identity (Call Sign or Registration mark) from the aircraft. It also enables to read out the flight level in 25 foot vertical resolution. Mode S Elementary Surveillance constitutes therefore a significant improvement of the Air Traffic Surveillance system in dense traffic areas.

Mode S Enhanced Surveillance consists of Elementary Surveillance supplemented by the extraction of airborne parameters known as Downlink Airborne Parameters (DAPs) to be used in the ground Air Traffic Management systems. This first step of air-ground integration will enable 5+% additional capacity to be gained, while maintaining Safety at the highest level. Some parameters are for Controllers display, known as Controller Access Parameters (CAPs), and some for (ATM) System functions enhancements, known as System Access Parameters (SAPs).

The need for Mode S

Mode S has the ability to offer stakeholders benefits as follows:

Improve safety by ensuring higher Surveillance data integrity and reducing RF interference level.

Increase capacity by overcoming the Mode A code shortage and reducing the controller workload,

Increase efficiency by providing the controller and ATC Support Tools with additional aircraft derived data thus increasing its efficiency in the radar separation tasks.

The conventional (M)SSR radar techniques reach their capacity limits. This takes the form of exceeded maximum number of targets, Radio Frequency (RF) pollution, lost targets and identity errors. Mode A Code shortage already exists in some high density traffic areas leading to grounding of aircraft in summer 1999, waiting for a mode A code allocation before being able to take off. Mode S is therefore a necessity in high-density areas and will form part of the basis of the Surveillance infrastructure until at least 2015.

To alleviate the problems with surveillance that are predicted to occur with the increase in air traffic, and in particular with the allocation of Mode A codes, the Mode S programme has been investigated principally in core Europe. Essentially this includes France, Germany and the UK but it is hoped to expand this area to include other countries in the future.

Mode S Elementary Surveillance will be introduced in March 2003. The Airborne Monitoring Project has been put in place to monitor the avionics and the European fleet before and during implementation of Mode S.

Objectives of the Mode S Monitoring Project

The main objective of this project is to ensure that the majority of the fleet in core Europe have the required surveillance capability by March 2003 and during the following transition period. To achieve this aim, the project includes plans for the development and implementation of tools. The tools are used to evaluate both the European fleet and the avionics hardware for the required Mode S Elementary and Enhanced Surveillance functionality. An assessment of evolution of the transponder equipage in the fleet in the two next years will be made to ensure that the mandatory process as set out in the Mode S roadmap can be met.

To ensure that the air traffic in core Europe is suitably equipped, three sites with POEMS (Pre-Operational European Mode S) stations giving good coverage over the area under evaluation, are used. These sites are at Orly in France, Dusseldorf in Germany and Gatwick in the UK and are being used in co-operation with the service providers STNA, DFS and NATS respectively.

All airborne-type Mode S problems encountered during the period of monitoring will be analysed and the outcome will be described in the Fault Report Procedure documentation. Following a Fault Report either rectification will be sought by direct interaction with the manufacturer or airline, or a problem will be resolved through the Implementation User Group.

Tasks

Two major project tasks have been identified as:

1. Transponder Evaluation: The task is to make an inventory of all transponder manufacturers and transponder equipment used and assess their performance, taking the prescribed action to rectify or resolve any problems.

The necessary tools are being built during the project or provided from elsewhere and then used to make the assessment. Each transponder is tested on the test bench at EEC for Elementary and Enhanced Surveillance characteristics and a test report is produced. A transponder database will be created of all existing transponder types with any associated problems.

This activity will be conducted in conjunction with bodies related to certification such as JAA and the CAAs of the Eurocontrol Member States. Anomaly and Fault Reports will be produced which will then determine the prescribed, corrective action to be taken.

In addition to the transponder evaluation using the test bench, the ongoing task into the investigation of problems occurring outside of test benching will continue. This activity will be restructured into a common procedure as described above, ending in a Fault Report.

Once a problem is identified by a fault report then an investigation will commence after which the problem will either be rectified or resolved. This will involve liaison with the manufacturers, airlines and regulators.

2. Fleet Evaluation: The task is to evaluate the compliance of the fleet with the Mode S Elementary (and Enhanced) surveillance requirement and to estimate the percentage of aircraft operating correctly. Corrective action and survey reports will result from the task. This survey will be done at two levels:

The detection of Mode S aircraft by Mode S interrogators using a common approach in Europe. (Initially POEMS equipped States will be taking part in the monitoring.)

Verification of the availability and, for certain parameters, the correctness of airborne parameters transmitted to the ground. Monitoring of the fleet will take place using ground stations in participating States together with adapted software tools. Problems detected will be recorded and the data will be co-ordinated by Eurocontrol. Reports of statistics will be produced and corrective procedures instigated. States, manufacturers and airlines will be associated in this process.

Aircraft Detection Monitoring Tools

To assess correct detection of Mode S replies Mode S and Mode A/C data from the same aircraft needs to be correlated. Several possibilities have been considered for recording Mode S and Mode A/C plots output from the ground stations.

Different solutions based on ARTAS (ATM suRveillance Tracker And Server system)V6, PTE Tools and SASS-C (Surveillance Analysis Support System for ATC-Centre) to perform this task:

Test Bench for Transponder Testing

Eurocontrol has sponsored the construction of a transponder test bench to test the functionality of Mode S transponders. It is able to test the transponder in the following scenarios:

Recreation of data flight conditions

MOPS compliance

Specific investigation

This tool is used by EEC Bretigny and the main objective is to test all versions of all transponders. By this means it will be possible to check all tests defined by the MOPS ED73A and to verify the transponder conformity with the TSO . Specific tests requested by the POEMS development will be also possible.

This test bench is capable for tests related to Elementary and Enhanced Surveillance aspects. Manufacturers will be given a report of successful testing of their transponder on the test bench.

Tools for Airborne Monitoring: ARTAS and BDAMS

The two main objectives of the airborne monitoring are to verify that all Mode S aircraft are seen correctly in radar coverage and the air data is downlinked correctly. To achieve the first objective a comparison is made between equivalent data received by a Mode S radar and a classical SSR radar, having a common coverage area. When analysing this data, an assessment of the detection capability involving the Mode-S transponder as well as the Mode-S radar station is made. For the second objective, the monitoring system has to identify discrepancies by checking the content of some downlinked Mode-S fields (i.e. aircraft ID).

The software tools ARTAS and BDAMS are used to perform the Mode S detection problems and air data analysis

Location of Tools and States Facilities

To perform the fleet monitoring, the participation of the service providers is required. The following picture presents the organisation that has been agreed with STNA, DFS and NATS:

Each record covers one week’s data of daytime (08.00-18.00) traffic. It is planned that these files will be analysed by States and if this is not possible then by Eurocontrol.

A bilateral agreement is established between Eurocontrol and the three countries providing data. This agreement defines the general conditions for formatting these records and their usage.

The analysed data will be consolidated by Eurocontrol, and the corresponding actions will be taken by "ad hoc" committee before publication. This committee is composed of the three concerned States and Eurocontrol.

Reporting

Transponder Reporting

At the end of the task of the Transponder Evaluation, a final report will be presented giving the general situation of the state of airborne equipment.

For all equipment tested a test report will be produced by EEC and forwarded to the corresponding manufacturer.

The transponder database will be upgraded.

Airborne Reporting

The output of the fleet evaluation will be issued every three months in order to report on the fleet evolution. At the end of the fleet evaluation, a final report will be presented giving the general situation on the state of the airborne fleet.

The status of particular parameters such as the Aircraft Identification and report of Air/Ground status will be presented.

Links

Further information is provided at

http://www.eurocontrol.int/mode_s/

http://projects.eurocontrol.fr/consultproject?LOID=6.0.143644

http://www.eurocontrol.int/artas/

http://www.eurocontrol.int/sass/

http://www.eurocontrol.int/surveillance/

Contacts

Mode S Programme Manager :

Pascal DIAS

EUROCONTROL