4.3.7  En route: Collaboration for Mitigating Local TFM Constraints due to Weather, SUA, and Complexity Constraints
It is noted that this concept element applies to all flight phases (Departure, Cruise and Arrival) in the operational domain of En route Airspace.
4.3.7.1 Problem
Deviations resulting from local traffic flow management (TFM) constraints are often excessive and not preferred by users, due to inefficient use of en route airspace in the presence of bad weather, SUA and complexity.
Currently, ATSP imposes constraints on users when NAS operations are predicted to be restricted in certain regions of en route airspace due to bad weather, SUA and airspace congestion/complexity. These constraints may take the form of speed changes, altitude changes, or path changes, all of which represent a deviation from the preferred trajectory planned by the user. In some instances, these NAS operational constraints may affect aircraft long before they are near the affected region of airspace.
In many cases, the deviations issued by the ATSP are different from what would be preferred by the user (both FD and AOC). There may be multiple ways in which the constraint can be satisfied, and the deviations imposed by the ATSP may not be the most efficient (or desired) in terms of meeting the users’ business objectives. Examples may include: the choice of flights to be deviated, the direction of the deviation, the type of deviation (route, altitude, speed), route deviations around airspace/weather through which the user might be willing to fly, or route deviations that involve flying through airspace/weather that the user would prefer not to penetrate.

Congested Airspace: Complexity (dynamic density) predicted to exceed threshold
Planned Path (airborne)
Planned Path (pre-departure)
Predicted Conflict

Fig. 4-4: Problems in Constrained En Route Airspace
4.3.7.2 Solution
A system-wide collaboration between ATSP and multiple users (FDs and/or AOCs), with the objective of eliminating or mitigating the impact of predicted NAS operational constraints due to bad weather, SUA and complexity.
The users are represented by the FD and/or AOC, depending on the situation and source of the user’s preference. Consider a scenario in which the ATSP predicts that a traffic management constraint will have to be imposed in en route airspace. A system-wide approach is used in which the ATSP collaborates with multiple users (who would potentially be impacted by the constraint) to achieve a resolution that would prevent the necessity of an operational constraint or at least mitigate the extent of the constraint.
The solution is characterized by user-ATSP collaboration which may vary in form as a function of time horizon (i.e., time to go until a particular flight, or group of flights, are predicted to reach the “constrained airspace”). This corresponds to three stages, categorized as Preemptive User Action, En route Collaborative Decision-Making (CDM), and Initiative Implementation.
　
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