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

Trajectory-Based Operations (TBO)
Study Team Report
The concept of vertical performance will likely need to start as boundaries of vertical airspace, similar
to what is used in an instrument approach:
These boundaries would represent known constraints that the aircraft would be capable of meeting, but
would allow the aircraft to set the most optimum climb or descent profile to pass through these
boundaries of vertical space. The vertical boundaries are tied to a 2D point in space. This waypoint
could have a time performance, as well. The ANSP would use these boundaries for conformance
monitoring, and the vertical airspace boundaries would represent conformance constraints. In selecting
the altitude windows that become conformance boundaries, the ANSP would initially use information
in the flight object relating to the requested climb profile provided in flight planning. After takeoff, as
the aircraft begins its climb, it could provide a new vertical intent to the ANSP to narrow the airspace
that must be reserved for the flight.
7.0 The Fourth Dimension of Time
TBO is dependent on time, and this time must be the same in automation, both in the air and on the
ground. At a minimum, clocks must be synchronized to the nearest second and set before taxi out.
Time can be derived from GNSS, uplinked as part of a broadcast message, or set manually using an
approved source of time. This synchronization is verified by the transmission of onboard time in data
link messages. While the time precision of flight performance is greater than a single second, seconds
of precision are specified for certain airspace and traffic density.
RTP varies with the flight operation and the density of traffic. Representative time performance
considers significant reductions in variability over the current NAS that, by itself, will gain capacity
and efficiency. For example, a reduction in landing runway occupancy time—from over the threshold
to exiting the runway—from 60 seconds to 45 seconds can produce 20 more arrivals per hour for that
runway. To realize this reduction in variability, TBO plans and provides for the time precision required
for the situation.
As an example, on departure, a time to reach a position in space may be provided as a controlled time
of arrival, expressed in seconds, to avoid or merge with crossing traffic, or to enable an uninterrupted
climb without intermediate level offs and greater power requirements. Time becomes the controlling
element for de-conflicting traffic and managing downstream flows.
There are two types of time: absolute and relative. In absolute time, the aircraft is proceeding to a
defined location in space at a prescribed time (hours, minutes, seconds of coordinated universal time
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