by Diana Khera
There are multiple working groups and divisions under the JPDO that work on topics related to airspace and procedures. There are two conceptual efforts that I would like to introduce to you; Trajectory Based Operations, and Flight Prioritization Alternatives for Super Density Operations.
Trajectory Based Operations is the fundamental premise behind far-term NextGen improvement and it refers to strategic and tactical flight planning and gate-to-gate traffic management, Trajectory Based Operations represents a shift from clearance-based to 4DT trajectory based control. The 4DT refers to the lat/long, speed and intent (or time) components of flight planning. A major benefit of 4DT is that it enables service providers and operators to assess the effects of proposed trajectories and resource allocation plans (including airspace availability), allowing both service providers and operators to understand the implications of existing demand and to identify where constraints need further mitigation.
In simple terms, TBO is final, most comprehensive, far-term phase of the FAA’s Big Airspace concept; so, what is the problem that this concept is designed to fix? The partitioning of current airspace into sectors is largely based on controller workload limitations . Automated separation assurance which is a part of the Trajectory Based Operations Concept will remove the workload limitations. In addition, some structural elements of airspace such as fixes and routes, which help controllers anticipate conflicts, may not be necessary. TBO will also create airspace flexibility, which does not exist currently due to the lack of decision support tools, and coverage limitations of both radio communications and radar. The flexible airspace that will be necessary to support TBO will also help elevate the problem of uniform demand and under-utilized controller resources. Several concepts are on the drawing boards for the TBO concept– from the more common ideas of corridors-in-the-sky through concepts for segregating traffic according to air traffic control category to finally the most ambitious and least defined concepts for large scale dynamic resectorization. The dynamic resectorization shows great amount of potential but great amounts of work is still needed by the JPDO, NASA, FAA and others in order to define the concept and prove operational feasibility.
As you can imagine, the TBO is a very complex concept and it involves changes in technologies , procedures, and policies. Some basic features of the TBO concept are: 1) trajectories are prenegotiated gate-to-gate, but are also tactically managed – this implies very high level of automation; 2) level of required aircraft performance will be driven by demands vs capacity; 3) user access priority still needs to be determined but we are reasonability sure by now that it will not be first come first serve; 4) some airspace may be exclusionary to trajectory based operations (especially at high altitude and/or super density areas).
Part 2, on super density, will follow soon – so stay tuned!