Trajectory-Based Operations (TBO) - Joint Planning and ...

Trajectory-Based Operations (TBO)
Study Team Report
Conformance monitoring for the 4DT supports a much smaller horn of uncertainty, 24 in that most of the
variability is now longitudinal in terms of time. Winds aloft will require frequent updates of the 4DT.
En route TBO automation will use conformance monitoring, flight object, aircraft position, intent, and
similar information from all other aircraft to look for downstream conflicts. It will do so by using the
ANSP strategic TBO evaluation services.
When a downstream flow contingency like weather must be considered, trajectories are reworked for
aircraft using the airspace, all the way back to the departures and forward to the landings. This
reworking is a continuous process that produces options that can be strategic (greater than 20 to 30
minutes in the future) or tactical (within 20 to 30 minutes). Strategic options can be shared with airline
operations/dispatch, since there is time to provide options for negotiation. Within the 20 minute
horizon, the controller shares options with the flight crew who can select their preferences. Once an
option is selected, the en route TBO automation uses this information to update the 4DT and, with new
intent information, receives intent verification from the aircraft through data link that the changes on
the flight deck have been implemented. The ANSP TBO evaluation service receives information on the
selected choice and updates the aircraft’s flight object for use in continuous 4DT and flow evaluations.
In some cases, the changes must be more tactical—a heading, speed, or altitude change. The aircraft,
when given this new clearance, is on an open trajectory. The open trajectory continues until a new
point in space and time is defined and the 4DT is updated.
The advantage goes to the equipped aircraft. The more capable the aircraft is, the more likely the
desired choices are known to the ANSP, and the easier it is for the ANSP to manage the aircraft. An
aircraft that is less equipped and in the airspace will require more work to implement a change in
trajectory.
Conformance monitoring parameters include the altitude, lateral displacement, longitudinal flight
track, and separation based on time, and time to the next point reported in intent. All monitoring
parameters can be adjusted based on traffic density and the need to meet downstream commitments for
separation, sequencing, and merging. The parameters are derived from a combination of the
performance requirements from the ANSP strategic TBO evaluation services and operator/pilot
capabilities and preferences. A business aircraft at FL 450 will have a different set of conformance
constraints than an air carrier aircraft at FL280 waiting to merge into an overhead stream at FL320. An
aircraft heading to a tightly controlled merge point or metering point may have a very tight time
performance, whereas another aircraft may have flexibility in time of many minutes. The parameter
tolerances for each aircraft are bounded by the performance capabilities of the aircraft, its crew and the
needs of the ANSP.
En route TBO automation supports:
• Considerable merging and sequencing
• Information on gaps in overhead streams to the ANSP strategic TBO evaluation service and to
counterpart departure and arrival TBO automation
• Blocks of vertical airspace for military special use and aircraft cruise climb maneuvers
24
The horn of uncertainty is a 3D representation of windows of reserved airspace in vertical, lateral,
and longitudinal axes requiring reservation for the aircraft based on its performance.
Joint Planning and Development Office
86