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

Trajectory-Based Operations (TBO)
Study Team Report
In today’s NAS, decision makers independently and cognitively determine how the weather would
impact operations. In NextGen, the 4D Weather Data Cube provides a common weather source of
observations and forecasts to all stakeholders, and this information is translated into volumetric
characterizations of potential operational constraints (e.g., where aircraft will and will not fly) to better
enable decision making.
Determining the exact time of storm passage at each airport is not possible hours in advance. But what
is possible is to work the number of arrivals and departures and begin to model the operational impacts
of just such a storm. For example, a reduction of capacity while the storm is in the vicinity of the
airport, or a projected wind shift with the frontal passage that would result in a potential
reconfiguration of the airport and airspace. Rather than wait until the storm arrives at Minneapolis or
Chicago and reactively put ground stops into effect, flights are proactively offered different 4DT
opportunities to change routing, climb higher, or change their timing throughout the day. Through netcentric
operations and common situational awareness, flights tracks are adjusted before departing for
the destination. Airports east of the storm are impacted as the front approaches. Some airlines may
elect to fly a more circuitous route around or over the weather constraint, while others arriving and
departing from an impacted airport must look to other options.
Weather forecasts from the SAS and potential constraint information are disseminated to the ANSP
strategic TBO evaluation service, providing the opportunity to examine multiple time slices, both
current and future. By examining 2100 to 2200 UTC ORD arrivals and departures, a projection is made
for demand. An estimated airspace constraint due to severe weather is obtained from the weather
translation capability that changes weather to airspace for modeling, and the TBO evaluation service,
using probabilistic metrics, determines a range of possible impacts on approved 4DTs. This range of
possible impacts will be continuously refined as updated weather forecasts are received and weather
constraints become better understood.
Those Chicago-area arrivals within the one-hour window of the expected front arrival and passage that
are not airborne yet will receive new 4DTs to delay their arrival. Those already airborne may receive a
new routing, a slowdown, a change in the location of TOD, or an arrival path based on the expected
arrival time of the storm. There is an exchange going on between the ANSP strategic TBO evaluation
service and both the ANSP surface movement management and departure/arrival TBO management
automation modules. The strategic TBO evaluation service is provided the best estimate of frontal
arrival and passage. The surface movement management module is receiving SAS information along
with local winds. The surface movement management module is examining the local departure hold
lists and those aircraft that are released for departures. It is receiving arrival information over the shortterm
from the departure/arrival TBO management module, and building a picture of when the best time
to change landing direction. This is fed back to both the departure/arrival TBO management module
and the ANSP strategic TBO evaluation service, and widely distributed through network-centric
operations.
Anticipating an airport and airspace reconfiguration, an aircraft is designated as the first to land from
the new direction and its 4DT. Aircraft that will subsequently land are modified to use the new
landing-flow direction. For some aircraft already on the arrival, they may receive a new 4DT that will
place them on an extended downwind for a RF turn to final in the new landing direction. Other aircraft
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