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

Trajectory-Based Operations (TBO)
Study Team Report
relies on disruption of operations to gain publicity. Most air carrier and large business aircraft could
continue to dispatch using inertial navigation and flying out of the interference area. No very-light jets
and smaller business aircraft carry inertial systems and would be dependent on a VFR departure only.
Most arrivals would continue, but the question is whether or not the vectoring workload would be too
great. Today, radar vectors manage the majority of arriving traffic at a major airport. In 2025, traffic
densities would nearly double, making radar vectors a fallback in the absence of any other alternative
PNT questionable because of controller workload. It is likely that demand would need to be cut back to
approximately half for air traffic controllers to handle a busy airport. The continuing intermittent
disruption of PNT raises the need to identify the maximum traffic density that could be handled by
radar vectors as a backup to GNSS and whether there is an alternative PNT strategy that could
continue to support TBO in the presence of GNSS interference or system failure.
16.4 Security Incident
An aircraft is deviating from its 4DT and not responding to communications. Alerts from conformance
monitoring have already sounded and the aircraft is being tracked with ADS-B, secondary, and
primary radar. Its destination and intentions are a mystery for the Department of Defense (DOD) and
the Department of Homeland Security (DHS). The ANSP’s job is to clear out airspace by modifying
the 4DTs of other aircraft. Some of this will be through the use of closed trajectories; others will be
open trajectory vectoring as control by exception. The situation is quite fluid, but simulations and drills
have established the boundaries of a new flight corridor for our deviating aircraft. As its flight track
changes, a buffer is established that will be treated by the ANSP TBO evaluation service and
distributed through network-centric operations.
While the concept of clearing the airspace is likely, the threat scenarios are highly variable. This
aircraft could have been in en route cruise, or could have just taken off. Time and location of detection
of the deviation plays a central role in the ANSP-required actions. What TBO brings to the table is the
continuous nature of conformance monitoring. Parameters can be built into the conformance
monitoring module to detect more than just a deviation from flight track. Speed changes, altitude
deviations, missed turn points, and erratic changes within the boundary of RNP performance can all be
detected and used as an early indicator of problems.
Time is lost in assuming that the aircraft has some other reason for deviating. By setting performance
parameters on conformance and linking this action to net-centric operations, common situational
awareness allows for earlier detection of rogue action.
AOCs are alerted to the event and the nature of incident. The AOC can verify intent and provide
necessary information to DHS and DOD. The ANSP’s TBO evaluation service begins to build a
moving temporary flight restriction (TFR) around the deviating aircraft against criteria that are preestablished
and based on speed and altitude.
16.5 Regulating Demand
Off-nominal operations require balancing demand with the capacity for conditions. The challenge is to
regulate demand only to the extent that it is needed to manage the throughput. A significant increase in
capacity (less demand constraint) will be realized just by shared situational awareness and the use of
network-centric operations to exchange information and strategically manage an event. This
transparency of actions helps to make control measures more realistic for the situation and removes
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