Guidebook for Advancing Collaborative Decision Making (CDM) at Airports (2015)

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14 At the heart of ACDM is data sharing between the various members of the airport community. To facilitate such data sharing, efforts have been made to standardize the names and definitions of the commonly used data elements across programs and airports. This chapter introduces and defines those terms that are most commonly used in ACDM and reviews the security issues involved in data sharing. Terminology The nomenclature of ACDM relies heavily on the use of acronyms. Additional terms and acronyms are presented in Appendix A. AOBT—Actual Off Block Time is the time the aircraft vacates its parking position to begin taxi for departure. ASDE-X—Airport Surface Detection Equipment Model X is a system that uses a combination of triangulation of aircraft transponder signals (termed multi-lateration), aircraft Automatic Dependent Surveillance Broadcast (ADS-B) broadcasts, and primary radar reflections to present an airport and surrounding airspace display of the position of all aircraft and includes individual data tags indicating flight identification, aircraft tail number, and other associated flight data. The update rate for this display is between one (1) and two (2) seconds. DRC—Departure Reservoir Coordinator is the position that utilizes readiness information and times the release of the departing aircraft from the parking or ramp area to achieve efficient aircraft taxiing and desired departure queuing so ATCT can achieve ACDM aims and objectives. EOBT—Estimated Off Block Time is the earliest time that the aircraft is available and ready to begin movement from the parking position. This time is utilized to forecast taxiing and departure demand so that the DRC can plan in advance and sequence an efficient and orderly departure flow. ESP—En Route Spacing Program is a program that results in generating and enacting a spe- cific departure time or range of departure times in order to sequence a departing aircraft’s posi- tion relative to other aircraft into the overhead stream that are subject to the same FAA traffic management restrictions. For example, if a certain timing or miles in trail is required for a specific airport, then the ESP program will look for a gap in the overhead stream and will issue a depar- ture time or range for the departure to fit into that gap. ETOT—Estimated Take-Off Time is a calculated take-off time that is determined by adding the expected taxi time to the EOBT or TMAT as appropriate. This enables the DRC to issue a push-back time from the parking gate to conform to traffic management restrictions, e.g., ESP C H A P T E R 2 Terminology, Required Data, and Security

Terminology, Required Data, and Security 15 conformance timing. This calculation enables traffic management conformance while sitting at the gate with engines off and thus reduces fuel burn and associated emissions. Movement Area—The airport operational surface area (taxiways, runways, holding area, etc.) that is under positive ATC control and requires a clearance from ATC to enter. Non-Movement Area—The airport operational area that is not controlled by ATC, usually the ramps leading up to and including the aircraft parking area. OOOI—Out of parking, Off the ground, On the ground, In parking (pronounced “OOO-E”) is a capability that provides four data points to measure and gauge the efficiency of aircraft ground movements. Avionics equipment on many airline and business aviation aircraft auto- matically reports these times to the operator via avionics, who in turn generally provides this report to the FAA. SOBT—Scheduled Off Block Time is the original planned departure time from the parking position and is updated by the flight operator if variances occur. This time is used for long-range initial planning before the operator provides an EOBT. TBFM—Time-Based Flow Management is the system that utilizes timing of air traffic to ensure the appropriate arrival demand at an airport. This technique can begin hundreds of miles from the arrival airport and includes display of sequence times to the various air traffic controllers so that when arrival streams merge, appropriate volume is generated and airborne holding is, in most cases, eliminated. TMAT—Target Movement Area Entry Time is used primarily at busier airports where large sections of aircraft parking and movement ramps adjacent to parking positions are controlled by non-FAA entities. These operations are complex and include significant vehicle movements to support the operation, which could include obstructions to movement from the parking posi- tion in accordance with a time issued by the DRC. Thus instead of parking position movement times, a TMAT is issued. This is the time that the aircraft should be positioned ready to enter the Movement Area. Data Source The type of data required in ACDM comes from multiple sources and multiple types of tech- nology. There is no one source for ACDM data because it requires collaboration from many to gauge and predict efficient aircraft movement. Table 3 displays the common source(s) of the various data points needed in ACDM. Once the data point source has been determined, their use is shown in Table 4, in chrono- logical order. The development of data interchange formats and standards by the FAA and international organizations is a major area of work. Regardless of the details of the standard, it is widely expected that standardized data formats and specifications will be employed in the near future. Two of the contenders in this arena are the Aeronautical Information Exchange Model (AIXM) and Flight Information Exchange Model (FIXM). Required Data The traditional FAA/Industry CDM program requires the operators to provide a series of aircraft movement data points to gauge and measure air traffic movement. Beginning in 2015, the following data points will be added to the CDM Message Set and are directly related to some

16 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports Sources FAA NEGS (SWIM) Operator/ Pilot DRC Airport Ramp Tower Airline Ops Center FAA ATCT D at a El em en t AOBT Actual Off Block Time ASDE-X EOBT Estimated Off Block Time ESP Time En Route Spacing ETOT Estimated Taxi- Out Time SOBT Scheduled Off Block Time OOOI PDRC Time (test program to time releasing of departures) TMAT Target Movement Area Time Table 3. Data point elements and sources. Data Point Usage SOBT Scheduled Off Block Time The time filed with the flight plan to indicate the initial planned departure from the parking area. The first time is to be used to estimate demand. This time could have great variance because it is usually submitted before operational variances occur. EOBT Esimated Off Block Time The updated earliest time that the flight will be available to depart from the parking area. This time is expected to be fairly accurate since it is generated much closer to the planned departure, and thus operational variances can be considered in formulating this time. This is the time the FAA will utilize to plan Time-Based Flow Management (TBFM). AOBT Actual Off Block Time Actual time the aircraft started movement from the parking area (part of the OOOI message set). Also detected at a few airports with surveillance. ETOT Estimated Taxi-Out Time The time estimated for the aircraft to move from the parking area to the runway for departure. This is used to calculate demand at the departure runway and to calculate an EOBT to the flight operator. TMAT Target Movement Area Time The time for the flight operator or ramp tower to position the aircraft for entry onto the Movement Area and transfer control to the ATCT. TMATs are utilized in areas of dense vehicle and aircraft movement ramp areas where timing for departure from the gate is impractical. Note: ESP system times are utilized by the DRC to calculate the desired time the aircraft should be at the runway for departure to conform to these and other traffic management activities. The EOBT or TMAT are then calculated by subtracting the ETOT from the desired runway time. Table 4. Data point uses.

Terminology, Required Data, and Security 17 possible ACDM programs. The standardization of this information sharing will be valuable in facilitating the creation of various ACDM programs going forward. • Updated SOBT • EOBT • OOOI times • Tail number of the aircraft—to match the intended flight with actual tail numbers to better gauge demand • Intended parking gate/area • Flight cancellation indicator Security, Privacy, and Proprietary Information Considerations As with any data, there are concerns about the usage and public availability of the data, espe- cially real-time position information with rapid update rates. Thus the FAA/Industry CDM program requires real-time data or display access to have a degree of security where it is not available for public display. Additionally, traffic management timing (EOBT and SOBT) could cause confusion about boarding availability if it is available to the general public; therefore, the FAA/Industry CDM program information is not available to the general public, and many current CDM members believe that ACDM data should not be publicly available. The general concept of the FAA/Industry CDM program is that if you share information, you see all the information shared (unfiltered) from everyone who shares the same data. This provides a degree of accountability among all participants. On October 8, 2014, the NextGen Advisory Committee formally recommended to the FAA that airports, if desired, have some type of FAA/Industry CDM program membership and/or access to CDM data. The recommendation has been accepted by the FAA/Industry CDM Steer- ing Group for action and implementation. This recommendation will impact all ACDM data distribution and decisions in the future, so airport operators must be aware of the constraints and desires of flight operators and plan for data security and restrictions.