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

Trajectory-Based Operations (TBO)
Study Team Report
may be brought in over the top of the weather and assigned a new arrival path segment. Weather
avoidance may also include a flow corridor where aircraft are routed because of gaps in the convective
weather, or because of areas reported or detected on radar as having passable conditions.
The bottom line is to handle weather strategically, based on airspace that is potentially constrained
during the development and transport of the storm. This still leaves aircraft that are scheduled to depart
or committed to land during the window of worse weather.
For runway changes, aircraft are held at the gate and given a start taxi time so they can load passengers
accordingly. Once off the gate, they are sequenced to expedite their flow to the runway end, such that
there are minimal or no queues that would either be trapped by the weather or require redirection
during runway swaps. Aircraft with taxi-out times close to the change in runways would be directed to
the new runway. The concept of managing departures off the gate is done using the functions of the
ANSP’s surface movement management module. This module knows the taxi-out time by aircraft type,
operator and gate, scheduling accordingly to avoid long queue formation during the worst part of the
weather. This feature also deals with the deicing requirements for each aircraft type to get airborne
within a specified interval.
Aircraft on arrivals and in the weather are avoiding intense storm areas using voice requests, and are
traveling in open trajectories under the direction of ATC through control by exception. The cockpit
workload is too great to accept constant changes to the 4DT during this phase of flight, and turbulence
may require speed and direction changes. Aircraft on RNAV/RNP arrivals can expect to fly the arrival,
but then receive vectors to downwind as the runway directions change. Those that arrive at the height
of the weather constraint may receive holding instructions as necessary to balance demand. Coming
out of holding, aircraft can expect a new 4DT provided by the TBO strategic evaluation service. The
demand cannot exceed what the controller can handle in control by exception.
Controllers are aided by automation to maintain a demand that can support the higher volume of open
trajectories that will be needed. Once the controller believes that the aircraft is capable of returning to
4DT, a clearance is issued to close the trajectory, and automation resumes separation responsibilities.
Deviations for weather are handled first under TBO as a strategic change through issuance of a new
4DT that considers weather, then as an open trajectory 4DT for maneuvering, then as an open
trajectory, with vectors as control by exception. Once established on an approach path, the trajectory is
again closed.
16.2 Runway Closing
A disabled aircraft on the runway creates this off-nominal event. The commuter aircraft had a right
main gear collapse during landing rollout, and the aircraft veered off to the right and is sitting partially
on the runway and partially on the grassy area. At the time of the event, two aircraft on final for the
same runway were sent around and re-sequenced. A third was sequenced into a gap in the arrival
stream for the parallel runway. Landing operations were shifted to the parallel runway that was in the
middle of a departure push and departures were held. Emergency vehicles are responding and those
aircraft taxiing are told to hold their current position.
Joint Planning and Development Office
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