Compilation of the research done by EuroControl/SESAR on the PHARE ATM project in the late 90s.

1. PHARE: A Compilation
Notes from the PHARE Program Reports

2. “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

3. 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

4. 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

5. 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.

6. 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

7. 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

8. Concepts (1)
• Trajectory Prediction
• Advanced Planning
• Multi-Sector Planning
• Tactical Load Smoother
• Arrival Management
• Departure Management

9. Concepts (2)
• Conflict Solving Assistance
• Co-operative Tools
• Flight Path Monitoring
• Air/Ground Negotiation
• Ground/Ground Negotiation
• Meteo

10. 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)

11. 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.

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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