PHARE: A Compilation

Notes from the PHARE Program Reports

“Programme for Harmonised ATM Research in EUROCONTROL (PHARE)”

• Future Air Traffic Management (ATM) concept:– Organize, co-ordinate and conduct studies and

experiments to demonstrate the feasibility and benefits of a future air-ground integrated air traffic management system

– Started in 1989 and completed in 1999

• Objective -- to prove that an integrated air/ground environment using advanced ATM tools and Human Machine Interfaces would provide increased airspace capacity

Program Design

PHARE comprised:• Initial concept definition and elaboration studies,• Development of tools (airborne, ground, communication and

supporting tools), and • Large scale real-time simulations (PDs)

Three PDs were planned:• PHARE Demonstration 1 addressing En-route issues• PHARE Demonstration 2 focusing on the Extended Terminal

Maneuvering Area (ETMA)• PHARE Demonstration 3 providing a multi-site integrated

experiment addressing flights from departure to arrival

Topics Addressed (1)

• Capabilities of aircraft with advanced navigation and flight management equipment

• Advanced automation support for air traffic controllers

• Modification of controller roles including new concepts of task sharing within groups of controllers and multi-sector planning

• Ground Human Machine Interface for efficient and effective use of the automation support

Topics Addressed (2)

• Use of data-link for air ground-ground information exchange, in particular for trajectory negotiation

• Better meteorological forecasting to improve trajectory prediction

• A common integration environment• A common methodology and standard set of tools

and procedures for experimental validation.

Concept-level (Evolutionary)Requirements

• Aircraft to have progressively more accurate navigational performance in space (2D, 3D) and ultimately in space and time (4D)

• ATM ground system to be continuously informed of each aircraft’s current position and its intentions

• ATC to exploit this high quality information through more optimal decision-making

Concept Summary• The trajectory used by the ground system shall

whenever possible be the trajectory generated by the aircraft systems

• The trajectory for an aircraft shall be chosen by the pilot and shall only be constrained by ATC when necessary for de-confliction or to follow defined procedures

• Flight trajectories shall be predicted taking into account constraints for the entire flight allowing management of the flight for greatest efficiency and economy

• Decision making shall not be automated to the extent that the human is out of the picture; automation shall assist, not take over

Concepts (1)

• Trajectory Prediction• Advanced Planning• Multi-Sector Planning• Tactical Load Smoother• Arrival Management• Departure Management

Concepts (2)

• Conflict Solving Assistance• Co-operative Tools• Flight Path Monitoring• Air/Ground Negotiation• Ground/Ground Negotiation• Meteo

Key Notes (1)

• Trajectory Predictor provides the following services:– Calculating optimal 4D trajectories, from aircraft current

position to last position on planned route.– Flight Path Monitor to confirm an aircraft is following the

agreed trajectory.• Advanced Planning

– Conflict detection has to be provided which supports the optimization of traffic throughput and early conflict resolution.

• Multi-Sector Planner is responsible for the medium-term planning of the trajectories that enter the Multi-Sector Area (MSA)

Key Notes (2)

• Tactical Load Smoother provides the Multi-Sector Planner with information regarding the future “complexity” of the Multi-Sector Area:– Predict and analyze the air-traffic situation that will evolve

some 10 to 40 minutes later.• Total number of aircraft• Number of conflicts• Complexity of the trajectories as assessed by number of vector

changes

– If one (or more) of the values passes the threshold level, an alarm can be generated to the Multi-Sector Planner.

Key Notes (3)• Arrival Manager is a ground based planning tool, used

to:– Support ATC in automatically establishing an optimal arrival

sequence– Enables ATC to manually edit the computed sequence– Provides for “what if” sequence generation

• Departure Manager is a ground based planning tool, used to:– Allocating departure runways and providing takeoff

schedules– Optimizing conflict-free climbing trajectories– ATC able to modify computed sequences– Includes a “what-if” mode

Key Notes (4)

• Conflict Probe executes every time a new trajectory is generated, searching the flight database to see if any other trajectory conflicted

• Co-operative Tools not only displays the conflicting aircraft but also aircraft that are close enough to the conflict for ATC to consider

• Problem Solver does not provide solutions independent of ATC, but allows them to model de-conflictions (simple mouse “drag-and-draw” function) and then issue the trajectory constraints to apply solutions

Key Notes (5)• Flight Path Monitoring compares 4D tracked

positions of aircraft against their 4D planned positions so as to detect deviations between them.– Deviations are calculated in three dimensions:

• Laterally• Longitudinally• Vertically

– For each direction, deviations are characterized as being insignificant, medium, or large (determined by Trajectory Predictor) and represent region of permissible error

Key Notes (6)• Trajectory Negotiation (TN) is the heart of air/ground

integration– Air and ground systems interchanged detailed information

about their requirements and come to an agreed contract for the execution of a flight (or the next segment of it)

– Aircraft down links full details of its preferred trajectory– Ground ATM assesses this for possible conflict and

responds with any necessary time or altitude constraints to prevent loss of separation

– Constraints are then applied from the preferred trajectory leaving the final agreement as close as possible to it

Key Notes (7)• Negotiation Manager (NM) tool developed to handle

trajectory passing between the ground sectors for ground/ground negotiation process– Studies found the NM was not compatible with the

prevailing methods of control, i.e. with Letters of Agreement (LOAs) for sector transfer etc.

– More work needed in future studies

• Meteo portion of project studied the accuracy of meteorological forecasting and wind forecasting and the effect on modeling and implementation of aircraft trajectories

Outcomes & Conclusions (1)• ATC who participated in the experiments clearly

recognized the potential of the PHARE concept• Also realized that it would lead to considerable

changes in their roles– Tends to reinforce planning rather than executive tasks

• Real-time trials on a variety of sectors showed:– Increasing traffic throughput (2X traffic load over 1989

baseline)– Maintaining an acceptable level of controller workload

• Study could not conclusively demonstrate increased capacity

Outcomes & Conclusions (2)• Successfully demonstrated that the concept of trajectory

control and trajectory negotiation could be conducted over a data link

• Reliability and performance of air/ground data link based on SATCOM proved insufficient to demonstrate the full capability of PHARE concept

• Ground ATM system tools appeared to achieve their aim of providing assistance to ATC

• PHARE concept works well in en-route control when there is sufficient time to exercise advanced planning– Sectors must be large enough to profit from a 20-minute or more

look-ahead• Significant reduction of ATC workload with 4D FMS and

data link equipped aircraft