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Advanced Safe Separation Technologies and Algorithms


Air transport around the world, but particularly in Europe, is experiencing major capacity, efficiency and environmental challenges to improve performance. The Airborne Separation Assistance System (ASAS) uses ADS-B (Automatic Dependent Surveillance - Broadcast) data to provide improved airborne surveillance in support of new procedures for controllers and pilots. ASSTAR addresses these critical issues by researching and validating two areas of ASAS Package II that have strong potential for short term operational and environmental improvements.

Project objectives

The objective of ASSTAR is to perform research into the operational and safety aspects of introducing the following ASAS Package II applications in order to make the significant potential benefit to the user community a reality in the 2010 plus time frame:

  • The delegation of conflict resolution manoeuvres to the air, in radar controlled airspace (i.e. crossing and passing), in order to reduce controller workload and improve flight efficiency.
  • The use of ADS-B to support new operations in oceanic and other non-radar airspace, enabling more optimal routing, including enhanced use of wind corridors, and passing and level changing, which are currently severely restricted due to the procedural separation standards.

The two themes will be brought together in the procedural definition, air and ground implementation and key safety assessment tasks to deliver a coherent set of operational procedures and algorithms for implementation in a practical, beneficial, certifiable and cost-effective solution.

Description of the work

For each of the two themes, the operational concepts and scenarios will be identified, analysed and defined. Airborne Self-Separation procedure in non-radar oceanic airspace above a certain flight level in so-called Free Flight Airspace will be included. The design of the applications will involve defining the functional logic and algorithms. These designs will be optimised by studying candidate functional processes, algorithms and task distributions. The optimisation measures will be safety, implementation ability and airspace capacity benefits. The result will be a set of well-defined and preliminary-assessed ASAS functions.

The procedures will be specified, refined and then reviewed by controllers and pilots. The detailing of the procedures will aim to simplify further standardisation and facilitate early implementation. Preliminary training requirements will be specified to facilitate building human competence and confidence. The result will be a set of detailed procedures and training requirements.

The air and ground infrastructure will be investigated, for both radar and non-radar scenarios. This activity will encompass elements of installation, certification and validation, resulting in a set of comprehensive deployment requirements. A benefits analysis, particularly in terms of the end users’ business case, will be prepared.

Feedback on applications will be given from the safety perspective with respect to hardware, software, human factors, environment and the interaction of these various aspects. The result will be to establish a set of safety recommendations and requirements, in terms of data and system redundancy and integrity, separation standards, etc., leading to a set of verifiably safe applications.

Expected results

The evaluation of these new applications will give an early determination of the air and ground difficulties, limitations, benefits and opportunities arising as a consequence of their introduction. This information on the airborne functionality and the accompanying ATC procedures will greatly benefit the future selection of advantageous ASAS functionality and will provide the template for future research into these advanced functions. Widespread dissemination of the results is planned.