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Assessment of Performance in current ATM operations and of new Concepts of operations for its Holistic Enhancement

Objectives of the project

At present, the European Air Traffic Management (ATM) is evolving in a coordinated manner aiming at improving the overall efficiency of air navigation services across several key performance areas (KPAs). In this context, novel operational and technical concepts are proposed in the SESAR programme, and the evolution of these concepts is driven by the European ATM Master Plan through a set of EU-wide performance targets set with the help of the Single European Sky (SES) Performance Scheme, which establishes an agreed methodological framework for performance targeting, measuring, baselining and benchmarking in ATM. 

The APACHE project proposes a new framework to assess European air traffic management (ATM) performance based on simulation, optimisation and performance assessment tools that will be able to capture the complex interdependencies between key performance areas (KPAs) at different modelling scales (micro, meso and macro).

The main objective of the APACHE project is three-fold: 

  • to evolve the Performance Scheme towards new methodologies and metrics capable to estimate the performance drivers of air traffic management (ATM) and to foster a progressive performance-driven introduction of new operational and technical concepts in ATM and in line with SESAR goals;
  • to make an (initial) impact assessment of long-term ATM concepts with the new APACHE Performance Scheme, measuring the impact on ATM key performance areas (KPAs) under different assumptions and hypotheses in line with the SESAR Concept of Operations 2020+; and
  • to analyse the interdependencies between the different KPAs at the Pareto-front of the ATM performance, by finding the theoretical optimal limits for each KPA and assessing how the promotion of one KPA may actually reduce (and in which proportion) the performance of other KPAs.

Some of the long-term ATM concepts to be explored in line with some SESAR solutions include: free-routing and/or continuous cruise climbs (CCC) for airspace users; dynamic airspace configuration (DAC) for air navigation service providers (ANSPs); and dynamic demand and capacity balance (dDCB) for the Network Manager (NM). All these concepts will be analysed at EU-wide and/or functional airspace block (FAB) level combined under different scenarios and case studies (considering to some extent uncertainty in ATM), and to illustrate the advantages of APACHE framework in assessing ATM performance.

Research approach


APACHE revolves around a novel framework that is expected to generate optimal trajectories at microscopic level, with the consideration of the business models of the airspace users, and integrate them into a futuristic air traffic flow management scheme where trajectories are strategically de-conflicted at the same time than airspace complexity is also assessed. This framework will be capable of capturing the complex interdependencies of traffic and weather at different scales across the main KPAs that define ATM performance. The same framework can be configured to reproduce current operations (structured en-route network, flight level allocation schemes, conventional air traffic flow management, static sectorisation, etc.). The following figure shows the overall concept of the APACHE framework.



  • Different scenarios to be studied will be defined, setting up different options regarding the demand of traffic and airspace capacities; the SESAR solutions to be tested; and the level of uncertainty to be studied.
  • The APACHE-TAP (trajectory and airspace planner) will be able to compute a set of optimal (ideal) trajectories and airspace sectorisations, as a function of the input scenario variables, in such a way that safety and complexity levels are maintained below an acceptable level. This set of optimal trajectories and sectorisations will form the different baselines for the new KPIs (key performance indicators) proposed in APACHE to assess ATM performance. In other words, they will be the reference values where the different “Deltas” (deviations from actual operations) will be computed.
  • The performance analyser module will be in charge of assessing these outputs (i.e. optimal baselines of traffic and sectors) generated by the APACHE-TAP and according to the different metrics implemented in the inner performance scheme (new KPIs proposed in the APACHE project and/or current KPIs).
  • This approach can contribute to generate knowledge on the complex interrelations among the different KPAs and may be useful to find the Pareto-front of the ATM performance.

Some interesting remarks arise from the proposed methodology:

  • The advantage of the simulation and optimization tools included in the APACHE is that they can be configured to represent different future or hypothetical scenarios and operational capabilities or contexts. 
  • The APACHE-TAP can be configured to reproduce historical scenarios too (i.e., recorded flight trajectories and sector configurations).
  • In APACHE, new proposed KPIs will coexist with the current performance scheme in order to benchmark the former against the second in current and futuristic operations.

The APACHE framework could be also set up to as a real-time prototype for monitoring and targeting ATM performance. These real-time capabilities could contribute to the effective implementation of Performance Based Operations (PBO). 

Research questions


The effective integration of micro and macro models in the APACHE framework will allow capturing the complex interdependencies among KPAs, which in turn will shed some light on the following (initial) research questions:

  • With regards to the limits of flight efficiency, how much fuel and emission reductions can be achieved by enabling user-preferred free routes at EU-wide level? If the aircraft operators can fly their optimal trajectories without any fixed ATM or airspace constraint (i.e., free routing including continuous cruise climbs)?
  • What is the expected impact in safety and capacity if free routing and/or continuous cruise climbs are implemented? Which are the capacity needs (in terms of number of sectors and configuration) to implement these in Europe if trajectories could be strategically de-conflicted to reduce complexity at sectors?
  • With regards to the limits of ATM cost-efficiency, what is (approximately) the minimum number of sectors needed to support the current operations and traffic demand to minimize ATFM delays? And to support Free Routing or continuous cruise climbs at EU-wide or FABs level? And what if the level of demand is a 50% higher, as forecasted for 2035?
  • With regards of ATM KPAs, can we estimate the Pareto-front? That is to obtain a representative set of equally efficient solutions in such a way that it is impossible to make any improvement in one particular KPA without making at least one other KPA worse.
  • In the presence of typical sources of flight uncertainties, such as wind prediction errors or airport delays, which might be the expected impact in predictability and robustness of the planning? Which strategies could be implemented to increase predictability and robustness and what might be the impact on other KPAs?

SESAR 2020 Exploratory Research Project