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

Trajectory-Based Operations (TBO)
Study Team Report
Departures can also take advantage of RNP 0.3 for separating aircraft, meeting environmental noise
flight tracks. As the aircraft moves further from the airport, it would transition to RNP 1. By improving
the precision of departure paths, new arrival paths can use the previously protected airspace. There is
no equivalent RNP value for surface movement, but as the visibility drops, cockpit guidance provided
by GNSS moving maps is for advisory use only and visual aids are used even in the lowest visibility.
There is a lateral opportunity here to use enhanced vision that relies on infrared sensors to provide eyes
in the fog.
6.2 Longitudinal Performance
Longitudinal performance is a combination of absolute and relative longitudinal distances and can be
managed by an assigned speed (time plus distance), time, or distance, or based on merging and spacing
software. More advanced aircraft will have conflict and detection software that can be used to select
and track other aircraft. If the pilot is assigned a relative longitudinal performance, it is in the context
of a follower of a lead aircraft. In maneuvering, it may be that one aircraft is expected to pass behind,
climb through the altitude of another, or pass. Merging and spacing software and conflict detection and
resolution software are used to execute these relative separation maneuvers.
Absolute longitudinal separation under TBO would be set by the 4DT and would likely be a point in
space with time as the separating metric. The concept of using time for separation, and therefore
setting the longitudinal performance, is a basic concept of TBO. The objective is to remove the
existing variability and increase the precision of distances between the aircraft being separated.
6.3 Vertical Performance
Vertical performance is not a discrete altitude unless in level flight. The climb and descent
performance are impacted by aircraft weight, winds, configuration, and the business case for the
trajectory. In today’s environment, the vertical uncertainty leads to intermediate level offs, stepped
climbs, progressive descent profiles, and other maneuvers to accommodate the ANSP’s need to protect
airspace for other users and preserve separation. In the far term, ANSP decision support automation
will monitor vertical performance and accurately predict 3D conflicts, freeing controllers from having
to manually predict 3D conflicts, and allowing a transition from separating airspace to separating
aircraft in 3D. Considerable improvements can be realized through knowing a closer approximation of
vertical performance. The aircraft is in a position to tell the ANSP the vertical performance. This is the
basis of the OPD, where the aircraft tells the ANSP its vertical performance to meet flows and time.
The TBO Study Team examined opportunities for using information from the aircraft to reduce the
uncertainty of vertical flight segments, refine the 4DT, and release airspace for use by others. One such
technique is the optimized performance climb that operates much like the OPD. Another is greater use
of cruise climb, a slow climb from initial cruise altitude to a higher optimum cruise altitude. Both of
these procedures improve efficiency and reduce fuel consumption.
Joint Planning and Development Office
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