Trajectory-Based Operations (TBO) - Joint Planning and ...
Trajectory-Based Operations (TBO) - Joint Planning and ...
Trajectory-Based Operations (TBO) - Joint Planning and ...
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<strong>Trajectory</strong>-<strong>Based</strong> <strong>Operations</strong> (<strong>TBO</strong>)<br />
Study Team Report<br />
Climb timing is also dependent on separation requirements downstream. Closer to the departure<br />
airport, time performance may need to be measured in seconds (e.g., + 30 seconds), whereas away<br />
from the airport, time can be anywhere between an ETA <strong>and</strong> + one to three minutes for a CTA.<br />
From an aircraft performance perspective, an RTP is executed by the FMS (with or without autothrottles)<br />
to a time performance capability of that FMS or individual pilot performance. In the FMS,<br />
time is input into the RTA function of the system. For aircraft without an FMS, the time precision is<br />
based on the ability of the pilot to fly a ground speed along a flight path that may be aided by tools that<br />
show aircraft progress in meeting time.<br />
Surface operations also have a time precision supported by the taxi-out time <strong>and</strong> the expected takeoff<br />
time. This time is measured in minutes, with the actual takeoff being used to reset the <strong>TBO</strong> time within<br />
ground automation.<br />
Just as with RNP, where lateral performance is expressed in different miles <strong>and</strong> fractions of miles, time<br />
is expressed in minutes <strong>and</strong> fractions of minutes (seconds). One performance does not fit all. In fact,<br />
<strong>TBO</strong> for arrivals at most U.S. airports can function with the use of the precision of an ETA. But at<br />
large hub airports or in metroplex airspace, time gets refined to seconds of performance.<br />
Table 1 provides some examples of representative time values for RTP. With review of surveillance<br />
information from ADS-B, actual variability can be measured starting at the l<strong>and</strong>ing runway threshold<br />
<strong>and</strong> working back to variability in takeoff times. Values in Table 1 represent a starting point for<br />
definition of actual requirements. As ADS-B becomes the norm, time performance requirements for<br />
traffic density <strong>and</strong> airspace complexity can be defined. The needed RTP is then compared to what the<br />
aircraft is capable of meeting <strong>and</strong> is adjusted accordingly. Note that Table 1 is built from the l<strong>and</strong>ing at<br />
the destination airport—the most deterministic portion of a flight—<strong>and</strong> built back to taxi-out at the<br />
departure airport.<br />
The <strong>TBO</strong> Study Team created the concept of RTP <strong>and</strong> has provided representative RTP values as goals<br />
<strong>and</strong> to serve as a starting point for time performance discussions. Variability <strong>and</strong> values require<br />
research to define. In today’s NAS, the current variability is unknown. Without this information, the<br />
actual time performance target for <strong>TBO</strong> cannot be set. RTP is being used because it is similar to the<br />
well-established RNP for navigation. RTP is the time performance that is executed in the FMS as an<br />
RTA. In cockpits without FMS, RTP becomes a progress check built on ground speed. In ground<br />
automation, RTP is represented as a CTA. While RTA <strong>and</strong> CTA represent a discrete time value, RTP<br />
is meant to specify a specific time window for performance, the margin needed to sustain one aircraft’s<br />
time dimension against all other aircraft.<br />
<strong>Joint</strong> <strong>Planning</strong> <strong>and</strong> Development Office<br />
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