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

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3 Overview of CDM Brief Overview of CDM History In this section, a brief overview of the FAA/Industry Collaborative Decision Making (CDM) program is presented to facilitate the understanding of the development of CDM. A thorough, detailed history is presented for the reader’s information in the following section. The evolution of the FAA/Industry CDM program is shown in Figure 1. In the mid-1990s, the FAA and flight operators came to the understanding that there had to be a more efficient way of conducting business. Missing or incorrect information was being used for decision making. For example, the FAA was using the Official Airline Guide (OAG) to forecast daily demand while the flight operators were using internal real-time data to adjust the schedules causing significant deviations from the OAG. In 1995, the FAA/Industry CDM program was officially initiated. In 1996, the FAA and industry developed graphical displays of air traffic demand that greatly facili- tated collaboration. In 1997, a common AOC (Airline Operations Center) network (AOCnet) was established to facilitate distribution of demand and delay data between not only the FAA and AOCs but also between AOCs. The benefits of collaboration were immediate because, for the first time, decision-makers understood what was occurring in the entire NAS, not just in their segment. From that point on, collaboration and participation increased; tools were developed not only to facilitate col- laboration but to allow the users to substitute delays between flights in order to enact business preferences. CDM became a philosophy of operations. Historical Development of CDM Though it was not called CDM at the time, Collaborative Decision Making began in 1993 when the FAA and major users of the NAS came to a consensus that the air traffic management system would operate more efficiently if planning were based on real-time airline schedules. Prior to that time, the FAA had used schedules as published in the OAG to forecast preliminary air traffic demand prior to operators filing actual flight plans. One of the first successes of CDM was when industry agreed to share real-time, day-of-operations schedules so that more accurate forecasting of air traffic demand could be obtained for managing operations. In 1995, CDM was officially established when a joint FAA/industry group defined roles and responsibilities for CDM, and the foundation for a collaborative air traffic management system was laid. Memoranda of Understanding (MOUs) were signed by both the FAA and various NAS users to codify these relationships. The MOUs detailed that CDM membership was restricted to the FAA and to NAS users who exchanged air traffic movement data with the FAA—airports were not included. The airport exclusion was not intentional; rather it was based on the MOUs C H A P T E R 1 AIRPORTFAA OPERATORS

4 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports requirements of stringent data exchange standards, and excluded vendor conflicts of interest. The move toward establishing CDM was further reinforced in 1995 by the Radio Technical Commission for Aeronautics (RTCA) Task Force 3 Free Flight Action Plan. Many of the Task Force 3 recommendations identified the need for joint planning and collaboration to ensure the efficient movement of air traffic. In 1996, the joint FAA/Industry CDM group defined the requirements for displaying air traf- fic demand to FAA traffic managers and flight operators, leading to the creation of the Flight Schedule Monitor (FSM) tool (Figure 2). The major attributes that FSM depicts are as follows: • Expected airport demand in time increments as small as 15 minutes. • Status of the demand, e.g., scheduled (green), active (red). • Degree of demand over/under capacity (white line indicates capacity). • Degree of demand that did not become active as scheduled (dark green). • The amount of delayed demand and the impact of delaying that demand. • Ability to illustrate the impact of demand vs. various capacity scenarios. FSM was a major breakthrough in the establishment of CDM. For the first time, NAS users had access to real-time operational information from both the FAA and flight operators. FSM enabled capturing real-time capacity through information exchanges, where previously deci- sions had been made on less accurate data, causing inefficiencies such as uncaptured capacity. Additionally, FSM detailed the down-line impacts of Ground Delay Programs (GDPs) for both the users and FAA traffic management personnel. The effectiveness of FSM eliminated much of the original mistrust of data sharing. Following this initial success, CDM became enshrined as a necessity rather than just another program. As time passed, joint FAA/Industry work groups were established and expanded under the auspices of CDM. Requirements for CDM membership were formally established, and funding was guaranteed as a line item in the FAA budget. These events, first introduced in Figure 1, are described in the text below. 1997—AOCnet was established, allowing NAS status (e.g., demand, delays, restrictions) information to be uniformly relayed in real-time to flight operators. 1995 1996 1997 1998 2000-2003 2004 2006-Present FAA/INDUSTRY CDM PROGRAM ESTABLISHED Agreed NAS had to be operated as one system together GRAPHICAL DISPLAY OF DEMAND Jointly developed common displays of ATC demand for FAA & Industry CDM AOCnet ESTABLISHED One common network for all to receive real time data CDM BEGINS USING COMMON DISPLAYS Real time full scale collaboration using common displays for FAA and operators, determining arrival rates and airport configurations collaboratively OPERATOR PREFERENCE TOOLS Flight operators can swap delays between flights for operator preference OPS ANALYSIS TOOLS Visual replay of flight tracks and delays for post-analysis ADDITIONAL TOOLS DEVELOPED Collaborative Wx forecasts, en route metering, added delay swapping tools Figure 1. FAA/Industry CDM program development timeline.

Overview of CDM 5 1998—Prototype collaboration for busy airports began with conference calls, data exchanges, and collaboration on appropriate airport configurations. 1999—The Volpe National Transportation Systems Center established the CDM Hub site to facilitate data exchange. 2000–2003—Development of CDM initiatives proceeded rapidly, including airline flight substitution—substitute one delayed flight for another in a modified schedule to enhance com- pany business objectives. 2004—The Post Operations Evaluation Tool (POET) was established. Prior to the creation of this tool, post-analysis of flight performance (route and altitude flown and delay encountered) was very difficult. POET presented a database where specific queries could be made concerning specific flights, or groups thereof. These queries led to open and forthright evaluations of both FAA and NAS user operations. 2006—The Airspace Flow Program (AFP) was established. Previously en route constraints could only be moderated with airport GDPs. This concentrated the delays on users of major airports where no constraint existed. AFP identified flights through the constrained area and distributed delay equally. 2007–2013—CDM continued to develop, adapt, and evolve many programs: • Adaptive Compression—Identifies flight list characteristics for compression to ensure that all available slots are utilized. • Collaborative Convective Forecast Product—Collaborative forecasting of weather that will constrain air traffic by FAA and industry experts, including the agreed degree of the constraint. • Re-route tools. • Weather forecasting products. Figure 2. Typical flight schedule monitor display for Hartsfield-Jackson Atlanta International Airport (Metron Aviation 2014).

6 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports • Collaborative Trajectory Options Set (CTOP)—Allows the NAS user to propose several route options for a flight and to predetermine the delay, making each option the preferred option. • Surface traffic management concept of operations. 2009—The CDM Steering Group (CSG) was established, which formalized some of the relation ships that had developed in the previous rounds of CDM activities. The formal struc- ture is depicted in Figure 3. The purpose of the CSG is to develop the most productive air traffic management ideas by allocating CDM resources from both the FAA and Industry into the most effective projects. This is accomplished by tasking specific teams, assigning appropriate person- nel, and providing regular reports to the CSG. In other words, the CSG is an administrative body controlling and regulating the work of the CDM teams. The teams are initiated by the task at hand and have a defined lifespan. The current teams are as follows: • Flow Evaluation Team—Reviews current en route operations and automation usage and sug- gests improvements. • Future Concepts—Identifies and develops future concepts. • Training—Develops training for joint FAA/NAS tools and concepts. • Weather Concepts—Works to improve forecasting. • Collaborative Automation Team—Automation and integration issues. • Surface Concepts—Developing surface traffic management concept of operations, focused primarily on departure metering procedures. Current CDM Membership Requirements CDM membership is limited to qualified aviation-related entities that meet the data sharing criteria (data that CDM determines is needed to operate the NAS more effectively). Due to the traffic management emphasis when CDM was originally formed, airports were not considered as having pertinent data to share. This is due to the fact that shared data was and is subject to the following rules: • CDM data is based on industry data and is considered proprietary. • CDM data is the property of the industry and cannot be released without the approval of the data providers. • CDM data is intended to support daily management of aircraft flight operations. • Only aircraft operators that provide individual CDM data will receive aggregate FAA CDM data; FAA will provide the proprietary CDM data to CDM participants only. FAA ATM-1Manager ATCSCCSys Ops PMOFAA CDM Manager A4A RepresentativeFAA Members Industry MembersNBAA RepresentativeAirline RepresentativeAOPA RepresentativeRAA RepresentativeIndustry CDM Representative A4A ATC Council ChairCSG Chair Figure 3. Governance of CDM by CDM Steering Group.

Overview of CDM 7 • All CDM participants are required to sign the CDM Memorandum of Agreement (MOA) effective March 1, 2009. The reasoning behind these data sharing restrictions is to ensure that a participant shared all pertinent data and does not have to be concerned that the data shared would be used in some negative manner. CDM emphasizes the trust of its participants to collaboratively share data to solve problems. This trust is essential in any type of CDM process. At the present, all CDM participants are responsible for the following: • All required training and documentation. • Software, as needed, to display and integrate CDM data in their individual systems. • Connection and alignment of CDM data communication interfaces. • Testing of data exchange capabilities. How Do CDM Activities Relate to Airport Operations? As is made apparent through its history, CDM, especially in the beginning, concentrated on traffic management initiatives and not on airport operations. In 2003, as a result of the FAA Free Flight project and NASA research and development, initiatives began studying surface traffic management. Tools, multi-lateration (triangulation of aircraft transponder signals) surveillance in particular, were deployed, and the benefits of common surface situational awareness led to significant industry interest in surface traffic management. This interest led to adjustments in the FAA Airport Surface Detection Equipment, Model X (ASDE-X) program to include usage of its surveillance ability, by airports and flight operators, to formulate surface management initiatives. In 2009, RTCA Task Force 5 (NextGen Task Force) declared surface traffic management one of its primary recommendations, and as a result, the FAA established the Surface Office in the System Operations organization. During this period and because of this activity and interest, the CSG established the Surface Concepts Team (SCT). The first tasking for the SCT was to develop a concept of operations for surface traffic man- agement, which represented a new focus for CDM on airport operations. In 2013, the SCT had completed this assignment and was holding Human-in-the-Loop Simulations (HITLs) to test concepts for metering flight departure demand from the parking gate. Successful departure metering requires movement predictions and information from several sources, thus this con- cept is one of the most visible examples of ACDM. HITLs are a significant expense and are being funded by the FAA, with system users (airlines and NBAA) and one airport operator providing additional expertise. The latest version of this concept is dated July 2013 and details a number of activities that involve the ingress and egress timing and control of aircraft to/from the Movement Area of an airport. These operational HITLs are trying to answer questions such as: • Who is best suited to operate the departure metering position: the airport operator, flight operators, or the FAA? • At busy airports, how can the combined operations of multiple ramp towers to stage depart- ing aircraft contribute to FAA control tower operational improvements? • How can departure capacity be distributed when the combined schedule of all operators, including general/business aviation, exceeds the capacity of the airport? • How is a flight that for some reason does not meet its controlled time, assigned a new time without a significant delay? • Should capacity be regulated by limiting the number of aircraft in a specific time period or by assigning a specific time to all aircraft?

8 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports • How would swapping of allocated departure times between operators be regulated? • Do the answers to these and many other questions differ from airport to airport? Some of these concepts require introducing control of aircraft movement activities in the Non-Movement Area, such as for push-back from the aircraft parking gate, specific times and locations for aircraft to be staged to enter the Movement Area, specific order of staging aircraft for entry into the Movement Area, flight departure readiness alerts, etc. Previously the Non- Movement Areas, where the airports and their vendors have the most activity, were not con- trolled by the FAA or by CDM processes. Introducing these control measures for Non-Movement Areas requires the participation of everyone involved with or enabling aircraft movement, including the FAA, flight operators, and airport operators and their respective vendors. Definition of ACDM This Guidebook defines Airport Collaborative Decision Making (ACDM) as a process, bring- ing together relevant airport stakeholders to improve operational decision making and share information, to enhance surface movement of air traffic, to reduce emissions and noise from air- craft engines, to mitigate events such as construction in the airport surface Movement Area, and to ensure that the airport system provides benefits for all. It achieves these objectives through collaboration among stakeholders, particularly related to data sharing in a real-time environ- ment. ACDM brings together air carriers, airports, government, private industry, and academia in an effort to improve efficiency and to reduce detrimental impacts to flight operations. The success of ACDM activities is determined through appropriate metrics, as is the case for all FAA/ Industry CDM activities. An example of this ACDM definition is the implementation of a Performance-Based Navi- gation (PBN) procedure. Utilizing the advanced navigation equipage capability on newer airplanes, procedures can be developed that reduce workload and reduce low altitude flying, which reduces fuel burn engine noise and associated emissions. A quick glance at PBN might erroneously indicate that if the FAA ATC facility and the flight operator technically agree on the procedure, it could be implemented. Experience has shown that PBN implementation requires a truly collaborative and inclusive effort since PBN implementations usually result in the fol- lowing issues: • New obstruction clearance conformance required of airports • The need for significant community outreach because flight paths will change, thus resulting in new noise exposure • Regulatory issues reference environmental impacts including impact on previous agreements both official and voluntary • Political exposure to community leaders • Training needs of all types. ACDM is a philosophy—not a particular project. ACDM Operations Today No airport in the United States has fully deployed and thus totally optimized all surface air traffic movements via the ACDM process. There have been several individual airport one-of-a- kind trials and decision support tool tests to partly enable or facilitate ACDM. These trial and decision support tool tests can be divided into three categories.

Overview of CDM 9 Actual ACDM Technology Tool Deployment The prime example in the United States is the ground departure-metering tool employed at JFK International Airport, initiated by the Port Authority of New York and New Jersey (PANYNJ) and operated and staffed under a contract with the PANYNJ (see Appendix C for details). The focus of this ground departure-metering tool is to control/limit the number of departing air- craft queued on an active taxiway at any one time. This simplifies the Air Traffic Control Tower (ATCT) workload, thus increasing the ability to efficiently sequence departures, and promotes fuel conservation and reduces emissions through reduced taxi time. Through monitoring and collaboration, it also provides an accurate real-time gauge of departure demand and facilitates planning to handle said demand and thus reduces taxi time and fuel burn. The effectiveness of this departure metering operation is inhibited by the lack of real-time ATC movement restric- tions impacting departures. Thus the ground departure metering function is metering flights without consideration of ATC traffic management restrictions. This lack of information is dis- cussed in various workgroups dealing with surface traffic management issues and is tentatively scheduled to be addressed in 2015. Research projects using decision support tools to control push-back timing from the gate and to manage departure queues have been initiated at some U.S. airports (Collaborative Depar- ture Queue Management at Memphis International and Orlando International Airports, severe weather reroutes at George Bush Intercontinental Airport, changing departure routes at Newark Liberty International Airport, and Pre-Departure Release Control (PDRC) at Dallas/Fort Worth International Airport). While these systems have shown benefit potential, they have not been fully developed; therefore, there has not yet been a full-scale deployment. Commercial Tools Leased/Purchased by the Airport or a Specific Operator These commercial tools are generally used to improve situational awareness applications, and their specific usage varies from airport to airport. At some locations, these tools have been locally adapted to perform specific tasks such as: • A tool utilizing privately installed multi-lateration antennas and flight matching capabilities, generating a real-time display of aircraft movements on or around the airport, which allows the user to gauge real-time positioning of flights for gate and ramp management. • An airborne tracking of flights using a slightly delayed feed from the FAA Aircraft Situation Display feed or real-time positioning via ADS-B generated information. • Airborne tracking of flights decision support tool that provides alerts for such activities as entering holding, diversion, or change of destination. Some local airport customization of these tools for local needs has been accomplished and includes the following: • Display of flight(s) requiring rerouting around severe weather and identification of flight(s) that have received the appropriate re-route, and • Aircraft de-icing status. Tools Not Intended for ACDM Technology but Sometimes Utilized as Such Several airports or users at some airports have coordinated with the local ATC facility and have automation displays/feeds from FAA systems to mitigate airport-specific issues. These

10 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports solutions are non-standard and not readily transferable to other airports. These include infor- mation access from the following capabilities: • ASDE-X, which provides the real-time position of all flights on the Movement Area of an airport; • Local area ATC radar; and • Information Display Systems (FAA internal displays) that provide controllers needed infor- mation on traffic management initiatives and restrictions. Many airports have Flight Information Displays (FIDs). There are several types of FIDs. In addition to passenger information displays, these systems are utilized to relay parking position information to various vendors operating on the airport ramp areas. Many operators display countdown parameters at each gate. These display flight number, destination, countdown to departure, etc., and are used to collaborate ramp activities toward on-time departure readiness. Such systems could be used to gauge an Estimated Off Block Time (EOBT), but such information is usually held internally. International ACDM ACDM efforts have been undertaken at several airports around the world. In general, the motivations are similar: reducing runway queues and taxi times, and as a result, decreasing envi- ronmental impacts. However, ACDM activities do differ in other world locations, due primarily to the very different operational and governance structures in place. Thus, while significant dif- ferences exist, a few examples of other ACDM efforts are described in this section, with hopes that they may help motivate the adoption of ACDM programs at U.S. airports. The International Civil Aviation Organization (ICAO) has been working to develop some stan- dards for ACDM that may be applied around the world, including influencing developments within the United States. Their initial guidance covers many of the same issues addressed in the Guidebook, although final guidance documents are not expected until at least 2015 (ICAO 2012). Europe The European Organization for the Safety of Air Navigation (EUROCONTROL) has an offi- cial ACDM program. To quote their web site (EUROCONTROL 2014): “ACDM is about partners—airport operators, aircraft operators, ground handlers, air traffic control and the Network Manager—working together more efficiently and transparently in how they work and share data. It allows better decision making, based on more accurate and timely information, with all airport partners having the same operational picture. The benefits are visible at a network level, with more accurate take-off information feeding into the air traffic flow and capacity management system run by EUROCONTROL’s Network Management. The network will be able to use the available capacity more efficiently. More effective use of slots results in reduced delays, improved predictability of events during a flight and optimized use of resources at airports.” The joint publication entitled “Airport CDM,” issued by Airport Council International, EUROCONTROL, and IATA, states (EUROCONTROL 2009): “the right information at the right time to the right people. Each partner has at some point a piece of information that is more up-to-date and more reliable than the estimates used by other partners; yet all too often this better information is not shared. CDM information sharing helps to create common situational awareness by making this information visible to those that are affected by it.”

Overview of CDM 11 The above quotes are graphically depicted in Figure 4 which is taken directly from the EUROCONTROL ACDM implementation manual (EUROCONTROL 2012). The EUROCONTROL target is to reduce the taxi time of every aircraft by three minutes and thereby gain both efficiency and environmental benefits. The advent of this program resulted from a research and development effort at Flughafen München Airport (Munich, Germany). As in most parts of Europe, the airport controls gate assignment for flights, with many of the same gates being used by different operators at differ- ent times of the day. The Munich Airport community developed an ACDM program so that gate usage, which is obviously impacted by traffic management regulations (the U.S. refers to these regulations as restrictions), could be coordinated and planned around EUROCONTROL regulations. The Munich Airport effort detailed many benefits of such an approach, but also illustrated the need for the entire community, including the airlines, to be involved for the best product. It also revealed that how an airport operates would dictate who is needed to be involved in the ACDM community. Paris Charles de Gaulle Airport enacted an ACDM effort where some, but not all, users are provided with a means for data entry to display maintenance delays and other factors involved in departure readiness. Additionally, the same users receive data such as departure runway and queue length. This effort originally only involved two airlines (Air France and FedEx) for test purposes and is being expanded as lessons are learned and systems and techniques are refined. Figure 4. EUROCONTROL ACDM objectives (EUROCONTROL 2012).

12 Guidebook for Advancing Collaborative Decision Making (CDM) at Airports A detailed statistical analysis of taxi times has been conducted at Paris Charles de Gaulle. This analysis resulted in an expanded and fine-tuned taxi time table, taking into account the aircraft category, in support of estimating a more accurate time at threshold (Andreeff 2014). The European departure metering systems differ from U.S. systems because flight operators in Europe generate many more data points than U.S. operations, e.g., EOBT, COBT (Controlled Off Block Time), and TOBT (Target Off Block Time). ACDM efforts in Europe are underway at Munich, Brussels, Paris Charles de Gaulle, Frankfurt, London-Heathrow, Helsinki, Düsseldorf, and Zurich airports with others expected in the future. The European CDM community has developed its own informational material on implement- ing Airport CDM. Their guidebook (EUROCONTROL 2009) was developed in collaboration with Airports Council International Europe and the International Air Transport Association. This doc- ument documents best practices; benefits (complete with quantitative examples); and descriptions of the experiences and lessons learned from airports that were early adopters of CDM in Europe. Table 2 summarizes some of the specific benefits reported from the European airport community. China China has instituted Airport CDM programs at most major airports. This was a result of growing ATC flight departure delays. This ACDM program did not significantly reduce delays, but did emphasize the fact that delays from major Chinese airports resulted from airspace con- straints and limitations on airspace availability to commercial aviation usage. Japan ACDM in Japan concentrates on environmental issues such as reduced emissions from taxiing aircraft due to emphasis on conformance to the Kyoto Protocol. The effort is in an organizational SAVINGS BENEFICIARIES Brussels Absorption of delay at the gate and no longer at the runway resulted in annual savings of: - 17,022 metric tons (t) of CO2 - 22 t of NOx - 5,400 t of fuel - 2.7M €/year in fuel saving Aircraft Operator, Airport Community Aircraft Operator, Airport Community Aircraft Operator Aircraft Operator Average reduction of taxi time outbound: 3 minutes Aircraft Operator, Airport Operator, Air Navigation Service Provider Munich Average ATFM slot adherence 93% in 2011 Aircraft Operator, Airport Operator, Air Navigation Service Provider 10% average reduction in taxi time Aircraft Operator, Airport Operator 2.65M €/year in fuel saving Aircraft Operator Paris Charles de Gaulle Average taxi-out time reduction by 2 minutes and 4 minutes in Adverse Conditions Aircraft Operator, Airport Operator Reduced fuel consumption: 14 t/day Aircraft Operator Reduced emissions: 44 t CO2/day Aircraft Operator, Airport Community Frankfurt Improved runway usage and take-off flow Aircraft Operator, Airport Operator, Air Navigation Service Provider Reduction of the impact of arrival delay leading to a more punctual departure and stable TOBT process Aircraft Operator, Airport Operator, Air Navigation Service Provider Table 2. Benefits reported by early adopters of airport CDM in Europe (EUROCONTROL 2013).

Overview of CDM 13 stage with workshops and educational programs being initiated beginning in Fall 2013. Specific system-wide procedures for all Japanese airports have not yet been initiated. ACDM in the Future The direction of ACDM, and departure metering in particular, in the future could and prob- ably will take several paths. • The airport may contract for specific placement (in airport control centers, local operation centers, Fixed Base Operators, police and fire stations, etc.) of movement and control displays to improve everyone’s situational awareness. • The FAA may develop decision support tools and data managers such as the Tower Flight Data Manager (TFDM) program to better forecast arrival and departure demand and decision making, which includes control and support of efficient flight movement from departure gate to arrival gate. • The CDM community, including the FAA, may continue to develop, refine, and test its Concept of Operation for surface traffic management. The future of ACDM can probably be reflected best by the following quotes from the “Surface CDM Concept of Operations” (FAA 2014a). It is a future with many facets and applications, but certainly involves airports. “The implementation of the Surface CDM concept is a pivotal component to improving the efficiency of traffic flows on the surface at U.S. airports, and achieving operational benefits across the entire NAS. Surface CDM progresses the FAA’s NextGen Implementation Plan (NGIP) [2] [3] [4] [5], which aims to provide advanced capabilities that make air transportation even more safe and reliable while improving the capacity of the National Airspace System (NAS), reducing the impact of aviation on the environment, and improving the experience of the traveling public.” “Understanding that ‘once you’ve seen one airport, you’ve seen one airport,’ the concept recognizes that implementation of Surface CDM may include the full suite of capabilities and procedures, or a subset of capabilities and procedures, in accordance with the needs and expected benefits at a particular airport. The full complement of capabilities includes: • Situational awareness among all Stakeholders to facilitate continuous, accurate predictability of air- port demand and capacity through transparent, real-time sharing of current and forecast operational information. • Strategic management of airport surface traffic flows and departure runway queues, thereby avoiding excessive taxi-out times, reducing emissions and optimizing airport capacity. • Management of airport surface arrival traffic flows that reflect known Departure Metering Procedures (DMPs) and predicted gate conflict information which optimizes available airport capacity. • Analysis, measurement, and monitoring capabilities that position stakeholders to better understand local airport operational performance and the impact on the NAS, utilizing a ‘Scorecard’ that provides an objective, transparent measurement of the performance of each of the local stakeholders. • Global harmonization and interoperability which facilitates interoperability across inter national Air- port CDM programs and the FAA’s Surface CDM concept.” From this historical review, it is obvious that ACDM concepts will evolve just as the FAA/ Industry CDM program has done. The ACDM evolution should not require the same lengthy timeframe since terminology, concepts, and data security issues can be directly transferred from the FAA/Industry CDM program.