Air-Ground Integration

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Air-Ground Integration

• Ed Bailey, Airborne Project Leader
• Ian Wilson, PATs Project Leader

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The Aim

• What is air-ground integration
• How was it done
• How should it have been done
• How it worked in practice - technical story of a
  flight

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PHARE Objective

• The objective of PHARE is to organise,
  co-ordinate and conduct on a collaborative
  basis, experiments and trials aiming at proving
  and demonstrating the feasibility and merits of a
  future air ground integrated air traffic
  management system in all phases of flight.

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PHARE Air/Ground Integration

• Integration in PHARE was limited to Trajectory
  Negotiation
• Trajectory Negotiation did not involve exchange
  of trajectories or Remote Procedure Calls
• Simply Trajectory Negotiation was
• Trajectory from the aircraft
• Constraints from the ground
• Equivalent toHere is my intent - is it safe,
  if not, make it safe

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Application Level View
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Ideal Trajectory Negotiation

• Aircraft downlinks User Preferred Trajectory
• Ground checks trajectory for conflicts adding
  constraints if necessary to deconflict and to
  sequence departure and arrival, then uplinks the
  constraints to the aircraft
• Aircraft modifies User Preferred Trajectory and
  downlinks it to the ground
• Ground checks the new User Preferred Trajectory
  for conflicts, broken constraints and
  infringements and if none uplinks deviation
  parameters to the aircraft
• Aircraft generates trajectory and downlinks
  Accept

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Its NOT that simple

• Problem areas -
• Is the first downlink really the User Preferred
  Trajectory ?
• What ground checks are really needed ?
• Does the controller need to see a trajectory that
  has no conflicts ?
• Is there a need to co-ordinate sector-sector on
  trajectory changes and what is the place of
  Letters of Agreement ?
• Delay during checks causes asynchronous work for
  controller

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User Preferred Trajectory ?

• Ideally Blue Sky trajectory
• But it includes known ATC restrictions such as
  Flight Levels and posslibly routings
• If the user does not get the request the
  alternative may be very different

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Ground Checks

• Negotiation Manager Software checks for
• Conflicts caused in current and neighbour sectors
• Constraints not met
• Changes in entry exit conditions at sector
  boundaries
• Conflicts must be checked, but the other checks
  may be unnecessary
• Forcing co-ordination not appreciated
• Time delay means controller may need to multi-task

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Controller display

• Does a trajectory without problems need to be
  displayed ?
• Depends on
• Trust in system
• Method of controller working - with tools it is
  not strictly necessary
• The Big Picture - is it still required by
  controllers with automated support ?

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Shortened Procedures

• Standard Trajectory Negotiation may be too long
  in some circumstances.
• Shortened procedures
• From Air - Pre-Emptive Negotiation
• From Ground - Formal Clearance

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Pre-Emptive Negotiation

• The aircraft is doing something therefore the
  ground is told not asked.
• Sequence
• Trajectory sent to ground
• Deviation parameters and accept
• Equivalent to Here is what I am flying - is it
  safe ? If not, make it safe.

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Formal Clearance

• The ground requires an aircraft to do something
  now therefore the aircraft is told not asked.
• Sequence
• Set of constraints and deviation parameters are
  sent to the aircraft
• The aircraft generates a trajectory and flies it
  when the pilot accepts
• Equivalent to Fly this trajectory.

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Flight Planning to 40 Mins

• Nominal values to process the information
• Trajectory Predictor Generates Initial Trajectory
  into Flight Data Base
• Flight Database distribution
• Conflict Probe on Trajectory
• Initial Arrival and Departure sequencing commences

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Air Trajectory Prediction

• The Trajectory is generated for the entire
  flight.
• SID and STAR (plus any procedural routings) are
  used for initial constraints.
• Trajectory is in 3 main Phases
• Climb,
• Cruise,
• Descent.

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Ground Trajectory Prediction

• For what-if modelling of all flights, by the
  controller and by the sequencing tools.
• For provision of advisories to the Tactical
  Controller to pass to non-equipped aircraft.
• Non-equipped - either without Datalink or with a
  less capable FMS.

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Aircraft Log In to Datalink

• Aircraft Provides trajectory based on aircraft
  data.
• Get Meteo data
• Derive vertical profile and 3D plus relative
  times
• Pilot checks then Negotiates
• First Trajectory Negotiation to Ground
• Ground sequences the flight and constraints
  passed for push-back and take-off

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Take Off

• DAP or trajectory indicating Take Off
• Trajectory now certain
• Re-negotiate Trajectory if required
• New contract if required

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Diagrammatic View of Planning and Control
Authority
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Post Take-off Planning

• Next Planner plans and deconflicts (using CP,
  CT, PS, TP, NM)
• Tactical controller monitors (using FPM and CT,
  PS, TP, NM if change required)
• Multi-Sector Planner 30 minutes away - checks
  loadings on the sectors (Using TLS and TP, NM if
  change required)

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Control by Pictures - Air
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Control by Pictures -
Ground
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Airborne Route Amendments

• Pilot amends route on AHMI
• Aircraft generates trajectory based on aircraft
  data.
• Constraints provided from the ground for en-route
  deconfliction and Arrival
• Aircraft recomputes trajectory to meet
  constraints and datalinks down
• Checked and Agreed with ground

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Automated Holds - Stacks

• Long lookahead to avoid holds
• If hold required trajectory predictors in the
  EFMS and on the ground create one
• If there are other aircraft in the hold a Stack
  Manager process on the ground provides descent
  constraints.

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Arrivals

• Sequencing continual while aircraft are en-route
  with sequence arrival times defined
• Changes of Time of Arrival only negotiated when
  change exceeds parameter time
• Automated sequencing frozen prior to descent

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Automated Approaches

• Expedite and Retard using trombones or approach
  fans
• Aircraft uses the area of the trombone or fan to
  amend its trajectory to achieve accuracies within
  5 seconds at the approach gate
• Always misunderstood by controllers

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Problems - Communications

• Datalink
• Slow, very low bandwidth
• Trajectory Information Structure
• System
• Some single threaded - resulted in unworkable
  delay
• If multi-threaded, controller also has to
  multi-thread

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Achievement of Concept

• PHARE integrated the aircraft and ground systems
• The aircraft generates the trajectory held in the
  ground flight database
• The aircraft is only constrained if required to
  avoid conflict
• Similar control by pictures approach both in the
  air and on the ground
• Data-Link with sufficient bandwidth is essential
  for full benefit

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Air-Ground Integration

• Ed Bailey, Airborne Project Leader
• Ian Wilson, PATs Project Leader