ENR 1.9 Air Traffic Flow Management and Airspace Management

1. General
   1. The Traffic Management System mission is to balance air traffic demand with system capacity, ensuring the maximum efficient utilization of the National Airspace System (NAS). A safe, orderly, and expeditious flow of traffic while minimizing delays is fostered through continued analysis, coordination, and dynamic utilization of traffic management initiatives and programs.
   2. While this list is not all inclusive, below are just a few of the most common initiatives and programs:
      1. Trajectory-based operations (TBO) is an air traffic management (ATM) method for strategically planning and managing flights throughout the operation by using time-based management (TBM), information exchanged between air and ground systems, and the aircraft's ability to fly trajectories in time and space. Aircraft trajectory is defined in four dimensions—latitude, longitude, altitude, and time. TBO will increase airspace and airport throughput, flight efficiency, flexibility and predictability through TBM, Performance-Based Navigation (PBN) procedures, and increased collaboration with NAS users regarding preferred trajectories and priorities. TBM operations include, but are not limited to, arrival metering, surface metering, terminal metering, and departure scheduling.
      2. Time-Based Management is a methodology for managing the flow of air traffic through the assignment of crossing times at specific points along an aircraft's trajectory. TBM applies time to mitigate demand/capacity imbalances while enhancing efficiency and predictability of the NAS. TBM techniques/tools will be used even during periods when demand does not exceed capacity. This sustains operational predictability and regional/national strategic plan. TBM utilizes capabilities within TFMS, TBFM, and TFDM designed to achieve a specified interval between aircraft.
      3. Traffic Management Initiatives (TMI) are techniques used to manage demand with capacity in the NAS.
         1. Properly coordinated and implemented TMIs are an important tool in the air traffic system. These initiatives contribute to the safe and orderly movement of air traffic.
         2. Any TMI creates an impact on customers. It is imperative to consider this impact and implement only those initiatives necessary to maintain system integrity.
      4. A Ground Delay Program (GDP) is a traffic management process administered by the ATCSCC when aircraft are held on the ground in order to manage capacity and demand at a specific location, by assigning arrival slots. The purpose of the program is to support the TM mission and limit airborne holding. It is a flexible program and may be implemented in various forms depending upon the needs of the air traffic system. The Expect Departure Clearance Time (EDCT) is calculated based on the estimated time en route and the arrival slot. It is important for aircraft to depart as close as possible to the EDCT to ensure accurate delivery of aircraft to the impacted location. GDPs provide for equitable assignment of delays to all system users. GDPs must be applied to all aircraft departing airports in the contiguous U.S., as well as, from select Canadian airports. Aircraft that have been assigned an EDCT in a GDP should not be subject to additional delay. Exceptions to this policy are miles-in-trail and departure/en route spacing initiatives that have been approved by the ATCSCC. GDP procedures do not apply to facilities in Alaska.
      5. Airspace Flow Programs (AFP) were developed to provide a dynamic method of implementing and managing ground delay programs. The creation and publication of Flow Evaluation Areas (FEA) and Flow Constrained Areas (FCA) serve to identify areas of limited capacity to system customers that require a reduction in demand through rerouting flights (voluntary or mandatory). An alternative to managing airspace congestion is to merge these two technologies and create AFPs. An AFP is a traffic management tool that assigns specific arrival slots and corresponding EDCTs to manage capacity and demand for a specific area identified by the FCA. It is important for aircraft to depart as close as possible to the EDCT to ensure accurate delivery of aircraft to the impacted area. AFPs may be applied to all aircraft departing airports in the contiguous United States and from select Canadian airports. Aircraft that have been assigned an EDCT in an AFP should not be subject to additional delay. Exceptions to this policy are miles-in-trail and departure/en route spacing initiatives that have been approved by the ATCSCC. AFP procedures do not apply to facilities in Alaska.
      6. Ground Stop(s) (GS) override all other traffic management initiatives. Aircraft must not be released from a GS without the approval of the originator of the GS. The GS is a process that requires aircraft, that meet a specific criteria, to remain on the ground. The criteria may be airport specific, airspace specific, or equipment specific; for example, all departures to San Francisco, or all departures entering Yorktown sector, or all Category I and II aircraft going to Charlotte. GSs normally occur with little or no warning. Since GSs are one of the most restrictive methods of traffic management, alternative initiatives must be explored and implemented if appropriate.