Attachment 1 -TBFM WP3 Functional Analysis Document.pdf

Federal Aviation Administration

Version: 1.0

Date: Nov 4, Functional Analysis Document

(FAD) for the Time Based Flow Management Work Package 3 (TBFM WP3) Program

Last Minute Changes Subsequent to finishing the set of documents that are required for Investment Analysis Readiness Decision (IARD), the tactical portion of the Metering During ReRoute Operations (MDRO) capability was removed from Work Package 3. It was decided that the concept of using the Convective Weather Avoidance Model (CWAM) data to predict individual aircraft deviations presented unacceptable risks for this capability.

However, the Strategic MDRO capability, in which Pre-Defined Metering Points (PDMPs) are used, is not a high risk and will remain in Work Package 3.

These tactical MDRO sections and several updates to the other concepts currently remain in the documents due to the lack of time and resources required to remove them prior to submitting final materials to the Joint Resource Council (JRC). These sections will be removed and updated in all documents once an IARD has been reached. Therefore, please disregard the sections in this document that pertain.

ii

5.4.6 Function 6: Schedule Flights To Runway Constraints ......................................... 5-26

5.4.7 Function 7: Sequence Flights To Terminal Constraints ....................................... 5-27

5.4.8 Function 8: Schedule Flights To Terminal Constraints ........................................ 5-29

Appendix A Context Diagrams .............................................................................................A-1 Appendix B Functional Hierarchy Diagram...........................................................................B-1 Appendix C N2 Diagrams .......................................................................................................C-1 Appendix D Lexicon.............................................................................................................. D-1

D.1 Data Decompositions, Inputs, and Outputs ................................................................ D-1 Appendix E TBFM "As Is" Functional Analysis ...................................................................E-1

E.1 TBFM "As Is" Functional Descriptions ......................................................................E-1 E.1.1 Function 1: Sequence Flights Through En Route Constraints...............................E-3 E.l.2 Function 2: Schedule Flights To En Route Constraints.........................................E-4 E.1.3 Function 3: Sequence Flights Through Arrival Constraints ..................................E-5 E.1.4 Function 4: Schedule Flights To Arrival Constraints ............................................E-6 E.1.5 Function 5: Sequence Flights To Runway Constraints..........................................E-7 E.1.6 Function 6: Schedule Flights To Runway Constraints ..........................................E-8

E.2 TBFM "As Is" Functional Hierarchy ..........................................................................E-9 E.3 TBFM "As Is" Functional Flow Block Diagrams .....................................................E-11

E.3.1 Function 1: Sequence Flights Through En Route Constraints.............................E-12 E.3.2 Function 2: Schedule Flights To En Route Constraints.......................................E-13 E.3.3 Function 3: Sequence Flights Through Arrival Constraints ................................E-14 E.3.4 Function 4: Schedule Flights To Arrival Constraints ..........................................E-15 E.3.5 Function 5: Sequence Flights To Runway Constraints........................................E-16 E.3.6 Function 6: Schedule Flights to Runway Constraints..........................................E-17

E.4 TBFM "As Is" N2 Diagrams ......................................................................................E-18 E.5 TBFM "As Is" Lexicon .............................................................................................E-25

Appendix F Acronyms ........................................................................................................... F-1

V vi

List of Figures Figure 5-1. Existing High-Level TBFM Functions ...................................................................... 5-2 Figure 5-2. Example of TBFM Delay Allocation ......................................................................... 5-3 Figure 5-3 Examples of Linked Metering ..................................................................................... 5-6 Figure 5-4. TBFM WP3 Operational Concept [FAA, 2012] ........................................................ 5-7 Figure 5-5. TBFM "To Be" Functional Hierarchy ..................................................................... 5-10 Figure 5-6. Sequence Flights To En Route Constraints Hierarchy ............................................. 5-11 Figure 5-7. Sequence Flights To En Route Constraints FFBD ................................................... 5-11 Figure 5-8. Schedule Flights To En Route Constraints Hierarchy .............................................. 5-13 Figure 5-9. Schedule Flights To En Route Constraints FFBD.................................................... 5-13 Figure 5-10. Generate Controller Advisories for Meter Point Hierarchy ................................... 5-15 Figure 5-11 Generate Controller Advisories for Meter Point FFBD .......................................... 5-15 Figure 5-12. Sequence Flights To Arrival Constraints Hierarchy .............................................. 5-17 Figure 5-13. Sequence Flights To Arrival Constraints FFBD .................................................... 5-18 Figure 5-14. Schedule Flights To Arrival Constraints Hierarchy ............................................... 5-19 Figure 5-15. Schedule Flights To Arrival Constraints FFBD ..................................................... 5-20 Figure 5-16. Generate Controller Advisories for Meter Fix Hierarchy ...................................... 5-22 Figure 5-17. Generate Controller Advisories for Meter Fix FFBD ............................................ 5-22 Figure 5-18. Sequence Flights To Runway Constraints Hierarchy ............................................ 5-24 Figure 5-19. Sequence Flights To Runway Constraints FFBD .................................................. 5-25 Figure 5-20. Schedule Flights To Runway Constraints Hierarchy ............................................. 5-26 Figure 5-21. Schedule Flights to Runway Constraints FFBD .................................................... 5-26 Figure 5-22. Sequence Flights To Terminal Constraints Hierarchy ........................................... 5-28 Figure 5-23. Sequence Flights To Terminal Constraints FFBD ................................................. 5-28 Figure 5-24. Schedule Flights To Terminal Constraints Hierarchy ........................................... 5-29 Figure 5-25. Schedule Flights to Terminal Constraints FFBD ................................................... 5-30 Figure A-1. Derive Flow Management Schedules Context FFBD............................................ A-1 Figure A-2. Derive Flow Management Schedules Context N2 Diagram.................................... A-2 Figure B-1. TBFM Functional Hierarchy Diagram .....................................................................B-1 F(gure C-1. Funct(on 0: Derive Flow. Management Schedules2 Diaf ...............................C-1 Figure C-2. FunctJon 1: Sequence Flights To En Route Constramts N Diagram ......................C-2 Figure C-3. Function 2: Schedule Flights To En Route Constraints N2 Diagram .......................C-3 Figure C-4. Function 2.6: Generate Controller Advisories for Meter Point N2 Diagram ...........C-4 Figure C-5. Function 3: Sequence Flights To Arrival Constraints N2 Diagram..........................C-5 Figure C-6. Function 4: Schedule Flights To Arrival Constraints N2 Diagram ..........................C-6 Figure C-7. Function 4.5: Generate Controller Advisories for Meter Fix N2 Diagram ..............C-7 Figure C-8. Function 5: Sequence Flights To Runway Constraints N2 Diagram ........................C-8 Figure C-9. Function 6: Schedule Flights to Runway Constraints N2 Diagram ..........................C-9 Figure C-10. Function 7: Sequence Flights To Terminal Constraints N2 Diagram...................C-10 Figure C-11. Function 8: Schedule Flights to Terminal Constraints N2 Diagram.....................C-11 Figure E-1. TBFM "As ls" Functional Hierarchy .......................................................................E-2 Figure E-2. Sequence Flights Through En Route Constraints Hierarchy ....................................E-3 vii

Figure E-3. Schedule Flights To En Route Constraints ............................................................. E-4 Figure E-4. Sequence Flights Through Arrival Constraints ........................................................E-5 Figure E-5. Schedule Flights To Arrival Constraints ..................................................................E-6 Figure E-6. Sequence Flights To Runway Constraints................................................................E-7 Figure E-7. Schedule Flights To Runway Constraints ................................................................E-8 Figure E-8. TBFM "As Is" Functional Hierarchy Diagram ........................................................E-9 Figure E-9. Function 0: Perform Time-Based Flow Management FFBD .................................E-11 Figure E-10. Function 1: Sequence Flights Through En Route Constraints FFBD ..................E-12 Figure E-11. Function 2: Schedule Flights To En Route Constraints FFBD ............................E-13 Figure E-12. Function 3: Sequence Flights Through Arrival Constraints FFBD......................E-14 Figure E-13. Function 4: Schedule Flights To Arrival Constraints FFBD................................E-15 Figure E-13. Function 5: Sequence Flights To Runway Constraints FFBD .............................E-16 Figure E-14. Function 6: Schedule Flights to Runway Constraints FFBD ...............................E-17 Figure E-15. TBFM "As Is" Function 0: Perform Time-Based Flow Management N2 Diagram .....................................................................................................................................E-18 Figure E-16. Function 1: Sequence Flights Through En Route Constraints N2 Diagram .........E-19 Figure E-17. Function 2: Schedule Flights To En Route Constraints N2 Diagram ...................E-20 Figure E-18. Function 3: Sequence Flights Through Arrival Constraints N2 Diagram............. E-21 Figure E-19. Function 4: Schedule Flights To Arrival Constraints N2 Diagram.......................E-22 Figure E-20. Function 5: Sequence Flights To Runway Constraints N2 Diagram ....................E-23 Figure E-21. Function 6: Schedule Flights to Runway Constraints N2 Diagram ......................E-24 viii

List of Tables Table 1-1. Description of Document Sections ............................................................................. 1-1 Table 5-1. Relationship of High-Level Functions to Constraint and Function Types ................. 5-9

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1 Introduction

1.1 Purpose

The Time-Based Flow Management (TBFM) Work Package 3 (WP3) functional analysis documents the functions and sub-functions that are expected to be available to Traffic Management Coordinators (TMCs), air traffic controllers, and flight operators. It will serve as the primary foundation for defining requirements and physical architectures, to support the acquisition of TBFM WP3.

1.2 Scope

From the operational perspective, this analysis details functions that support the WP3 Concept of Operations [FAA, 2012]. The included functions are decomposed hierarchically and are depicted using standard systems engineering methodologies described in the Federal Aviation Administration (FAA) National Airspace System (NAS) Systems Engineering Manual (SEM) [FAA, 2006]. Per the NAS SEM, the functional analysis examines a system's functions and sub-functions necessary to its operation or mission.

The functional analysis describes what the system will do without specifying how to do it. It is a living document that will be updated as capabilities evolve to encompass future functionality.

This analysis is conducted at a level that supports later synthesis and acquisition efforts.

1.3 Rationale

As described in the TBFM WP3 Preliminary Shortfalls Analysis [Johnson et al., 2012], TBFM WP3 provides enhancements to address identified shortfalls in the current system.

1.4 Document Organization

This document contains the sections described in Table 1-1.

Table 1-1. Description of Document Sections

Sedion I Purpt1sc

Section 1: Introduction Introduces the document and provides the purpose, scope, and rationale

Section 2: References Lists the references used in the analysis

Section 3: Resources Describes the resources used in the analysis to include team members, stakeholders, and software tools.

Section 4: Methodology Describes how the analysis was conducted, and its inputs and outputs

Section 5: Analysis Provides the results of the analysis, including assumptions and findings; as well as a summary of each function

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The detailed information documenting the analysis is provided, in accordance with the NAS SEM, in the following appendices:

• Appendix A: Context Diagrams

• Appendix B: Functional Hierarchy Diagram

• Appendix C: N2 Diagrams

• Appendix D: Lexicon

In addition, Appendix E documents the TBFM "As Is" functional analysis that served as the basis on which the TBFM WP3 functional analysis was built. Appendix F provides a list of acronyms and their definitions.

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2 References The following is a list of references relevant to this functional analysis document:

• Federal Aviation Administration (FAA), National Airspace System (NAS) System Engineering Manual, Version 3.1, 11 October 2006, FAA website:

http://www.faa.gov/about/office erg/headquarters offices/ato/service units/operations/sy sengsaf/seman/

• FAA, Final Program Requirements for Time-Based Flow Management (TBFM), 22 September 2009

• FAA, Time-Based Flow Management (TBFM) System Specification Document (SSD ), 7 December 2011

• FAA, Concept of Operations For Time Based Flow Management (Draft, 27 December 2012)

• Sekhavat-Tafti et al., TBFM WP3 Enterprise Architecture products, The MITRE Corporation, McLean, VA, (to be published 2013)

• Johnson, C. M., et al., TBFM WP3 Preliminary Shortfalls Analysis, The MITRE Corporation, McLean, VA, (to be published 2013)

• Lockheed Martin, Time Based Flow Management (TBFM) System/Sub-system Specification (SSS), FAA-TBFM-2010-xxxx, Informal Draft, CDRL E03, 18 February 2011, Lockheed Martin, Rockville, MD

• Lockheed Martin, Time Based Flow Management (TBFM) System/Subsystem Design Description (SISDD), FAA-TBFM-2011-0398, Final Release 3.14.0, CDRLE04, December 2011, Lockheed Martin, Rockville, MD http://www.faa.gov/about/office

3-1

3 Resources

3.1 Team Members

The following team members participated in the performance of the functional analysis and the development of this document:

• FAA Program Management - Systems Integration and Requirements Analysis - Engineering Analysis -Emerging Systems Office (AJM-121)

• The MITRE Corporation's Center for Advanced Aviation System Development

(MITRE/CAASD)

3.2 Stakeholders

• FAA Program Management Organization (AJM)

3.3 Software Tools

The following software tools were used to produce this document and depict the functional decomposition and data connections:

• Vitech Corporation's CORE' systems engineering software package

• Microsoft Word

• Microsoft PowerPoint

1 CORE is a federally registered trademark of the Vitech Corporation.

4-1

4 Methodology The TBFM WP3 Functional Analysis was performed following the guidance in the NAS SEM [FAA, 2006], which calls for defining functions based on needs identified to improve the current system. A shortfall analysis [Johnson et al., 2012] documented where TBFM WP3 can address issues identified in time-based traffic flow management operations. An updated concept of operations [FAA, 2012] describes how TBFM WP3 improves operations and the situations in which it is expected to be most useful. The functional analysis translates the needs identified by that previous work into functions to address those needs, iteratively refining and clarifying what functions are needed as well as how they interrelate. This functional analysis supports the development of detailed functional requirements. Based on the analysis, additions and changes to the top-level TBFM "As Is" functions were defined and those functions were decomposed into lower-level functions. At each level, the associated functional interfaces were also defined. The resulting functions and their interfaces were documented using functional flow block diagrams (FFBDs) and data connection (N2) diagrams respectively. This iteration of the TBFM WP3 functional analysis resulted in the first- and second-level functions. Future iterations may further decompose the functions.

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5 Analysis The TBFM system provides a suite of capabilities to improve traffic flow efficiency throughout the NAS. To do so, the TBFM system fulfills three core objectives:

1. Sequence flights to a constraint

2. Ensure that those flights are not in conflict at the constraint

3. Assign a scheduled time of arrival for each flight at a scheduling constraint in an attempt to optimize the flow of traffic

5.1 General TBFM High-Level Functions

To fulfill these objectives, TBFM takes information from various automation systems (as shown in Figure 5-1) and uses that information to perform a number of functions that will be described in detail in this document. These detailed functions are summarized in Figure 5-1 with two high level functions-"Sequence Flights To Constraint" and "Schedule (and Deconflict) Flights To Constraint"-that allow TBFM to provide flight-specific information for display to appropriate controllers, and flight and constraint-specific information for display to appropriate traffic managers.

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System lnti:rnaticmal Fl/fhtand Tra,kData tight5pedlc Del.iv

Wind arid Convective Weather For11,ast!i Constraint Seq11ence, sch11dule, and Fffght SpiN:lflc Delays

Airspace Deflnltlons

Constraint Paramet1u·s rrr,,,_1

Comtramt Si!quen,e, Schedule and Flight Specrf1c Dell

Figure 5-1. Existing High-Level TBFM Functions

5.1.1 Sequencing

First, TBFM uses the information from various automation systems to sequence flights through a constraint. This involves developing a four-dimensional trajectory for the flight based on data including the current position of the flight, the flight plan, and wind forecasts. The trajectory includes estimated times of arrival (ETAs) at the constraint and other points along the trajectory.

Next, TBFM develops a sequence of flights through the constraint, ordering the flights by earliest ETA to latest.

5.1.2 Scheduling

TBFM then passes the sequence of flights developed in the sequencing function to the scheduling function along with key pieces of information from the four-dimensional trajectory.

TBFM uses this information to assign each flight a scheduled time of arrival (STA) that meets the constraint parameters entered by the traffic manager, such as a miles-in-trail (MIT) restriction at the scheduling constraint. TBFM considers each flight in order of the previously developed sequence. For each flight, TBFM assigns the earliest available STA at the schedule constraint that is later than the flight's ETA and does not violate any of the constraint parameters. It is

5-3 primarily through this scheduling process that TBFM ensures flights are not in scheduling conflict as no two flights can be assigned the same STA. The difference between a flight's STA and ETA becomes the delay that the flight must absorb prior to crossing the scheduling constraint.

TBFM continues to recalculate the sequence and schedule for each flight approaching a constraint until the flight crosses within a pre-defined distance of the constraint. Upon crossing this point, known as a "freeze horizon," the sequence position and schedule time for that flight are "frozen" and the flight's assigned delay is displayed to the appropriate controller for implementation. Even when frozen, TBFM continues to update the flight's trajectory according to the latest information. When the flight's ETA at the scheduling constraint changes, the corresponding change in delay that must be absorbed is calculated.

To assist controllers with implementation, a set of upstream (e.g., closer to the departure airport) arcs are linked to each scheduling constraint. These arcs are pre-defined in adaptation along with the amount of delay that can be safely absorbed by a flight between each successive arc. The delay that is to be enforced by a specific controller is calculated based on the delay that can be absorbed between each arc (Figure 5-2).

TBFM allocates 1 minute of delay between Arc 2 and Arc 1 TBFM allocates the last minute of delay between Arc 1 and the Meter Fix

SGl!edulmg ConStra.l

Freeze Horizon

Arc2

Arc 1 t ,---J _..-- 2 minutes 1 minute 1 minute

Examples of delay allocat101t- ..,,4 minutes

Airport

Total Delay

Figure 5-2. Example of TBFM Delay Allocation

5-4

5.2 Forms of TBFM as of WP2

The constraints to which TBFM functionality is applied come in three primary forms:

• Meter Points (MPs) are typically located within Air Route Traffic Control Centers (ARTCCs).

• Meter Fixes (MFs) are associated with an arrival airport and are typically near the boundary of the Terminal Radar Control (TRACON) facility overlying that airport.

• Runway constraints at arrival airports are applied at either the runway threshold or at the Final Approach Fix (FAF).

TBFM is capable of developing a sequence and schedule to each type of constraint as well as schedules that take into account combinations of these constraints. Conceptually, TBFM continues to apply the same two high-level functions of sequencing and scheduling to each type of constraint, though each has unique aspects that are reflected in the functional decompositions in the appendices.

MPs, MFs, and other scheduling points can be referred to as Constraint Satisfaction Points (CSPs). A CSP is any point at which TBFM is de-conflicted aircraft and building a schedule to.

It should be noted that CSPs are a subset of the most generalized grouping of adapted airspace elements in TBFM, known as Meter Reference Elements (MREs). While comprehensive lists of MRE types can be found elsewhere [Lockheed Martin, December 2011], MREs that are not CSPs include airspace elements such as outer arcs and outer-outer arcs. Elements such as these are associated with a specific CSP and are typically located on or near sector boundaries upstream of the CSP and are primarily used by TBFM to calculate how delay that was assigned at the CSP should be allocated among the sectors upstream of the CSP, as previously explained.

As alluded to previously, TBFM is not always as operationally simple as taking one of these constraints, such as a meter fix, and building a sequence and schedule to it. There are three distinct types of metering performed by TBFM that each use one or more of the previously-described constraints to develop schedules that address an operational need:

• En route metering

• Arrival metering

• Linked metering

5.2.1 En Route Metering

For en route metering, Time-Based Metering (TBM) is applied to an MP without considering other TBFM constraints. TBFM can be used to optimize the flow of flights through an MP whether the flight is waiting to depart or is already airborne. When a flight is waiting to depart from an airport that is within the same ARTCC as an MP, TBFM will assign an STA at that MP to the flight at the request of a traffic manager. TBFM will also calculate the departure time for the flight that will allow it to meet its MP STA based on a nominal time of flight for the flight's aircraft type from the airport to the MP. Airborne flights are sequenced and scheduled along the lines of the general process previously outlined.

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5.2.2 Arrival Metering

For arrival metering, TBFM is applied to MFs while considering the runway constraints for the airport associated with those MFs. Sequencing and scheduling to an MF operates much the same way as with an MP except that TBFM must consider the schedule at each runway the MF is feeding and assign a runway to each flight. To do this, TBFM develops a sequence and schedule to each runway along with a sequence and schedule to each MF associated with the airport. The MF STA for each flight will be assigned such that the flight meets the constraints at both the MF and the assigned runway. The runway assignments will be selected such that the total delay given to all flights arriving at the airport in question is minimized.

5.2.3 Linked Metering

TBFM can also be used to develop linked schedules between CSPs. This linked metering can come in a variety of forms (see Figure 5-3) and can include links between: an MP and an MF, a chain of MPs, a chain of MPs and an MF, or an MF linked to multiple MPs that are not linked to each other. In these linked scheduling "arrangements," the sequencing and scheduling of a CSP is performed while taking into account information from linked CSPs upstream and/or downstream in the flow. This allows traffic managers to apply TBFM at greater distances from an arrival airport.

The communication of information between linked CSPs can be performed via a feed-forward and feedback mechanism or solely via the feedback mechanism.

For linked metering using both the feed-forward and feedback mechanisms, TBFM develops trial schedules at each upstream CSP as outlined in en route metering. With this trial schedule, a "weighted ETA" is calculated at the downstream CSP. This weighted ETA is a weighted average of the usual ETA and an adjusted ETA calculated by assuming the flight arrives at the upstream CSP at the trial STA. The downstream CSP schedule is then calculated normally but using the weighted ETAs in place of actual ETAs. This is the feed-forward mechanism. Any delay needed at the downstream CSP that cannot be absorbed between the two CSPs is sent to the upstream CSP schedule and added to the delay that must be absorbed prior to that upstream CSP. This is known as "passback delay." The upstream CSP schedule is recalculated and weighted ETAs are again passed forward to the downstream CSP. This process is repeated until stable schedules are reached at both CSPs. Examples of this are shown in Figure 5-3 diagrams A and C.

For linked metering using only the feedback mechanism, the process is a bit simpler. Weighted ETAs are not used so only passback delay is applied. This means that any projected delay for the downstream CSP that can't be absorbed between the two linked CSPs will be added to the delay assigned by the upstream CSP. An example is presented in diagrams B and C of Figure 5-3.

5-6

Meter Point • , ',

a) I rnnnlPrl C:.rhPrln Hn Ct hPtWPP.n MP nrl MF Met« f

J inkNt Fn RnntP MP,;:

MfflrPo\nt (UpwUmofMeterflw./ Downstream of other

In the examples below,flights would progress downstream flying left to right

Figure 5-3 Examples of Linked Metering

5.3 Future Capabilities

This section provides a high-level description of the operational concept for TBFM WP3, as documented in the "Concept of Operations for Time-Based Flow Management (TBFM)" [FAA, 2012]. The concept for TBFM WP3 includes four capabilities: Metering During Reroute Operations, Path Stretch Controller Advisories, Terminal Sequencing and Spacing, and deployments of Integrated Departure Arrival Capability (IDAC) to additional sites.

Figure 5-4 depicts the operational concept for TBFM WP3, reflecting where proposed capabilities target improvements in various phases of flight (departure operations, en route/cruise, arrival operations) within the NAS.

5-7

Figure 5-4. TBFM WP3 Operational Concept [FAA, 2012]

5.3.1 Metering During Reroute Operations

Metering During Reroute Operations allows controllers and traffic managers to continue the use of time-based metering more often and in more situations, particularly those situations not well supported by current metering automation (such as convective weather). If weather is affecting nominal metering routes or corresponding Constraint Satisfaction Points (CSPs), preventing their use, traffic managers strategically shift the metering operation, using "playbook-like" options, to CSPs unaffected by the weather. Controllers continue to meter and deliver aircraft accurately to the new designated CSPs. When flights are making small deviations around weather, system enhancements predict the deviation and update the predicted times shown to controllers. This provides the controllers with more accurate and useful information, allowing them to continue the metering operation and ensuring a more accurate delivery of aircraft to the downstream CSP.

Continued use of time-based metering during situations that could benefit from its use reduces delays and improves overall efficiency within the NAS.

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5.3.2 Path Stretch Controller Advisories

Path Stretch Controller Advisories provide air traffic controllers with new tools and procedures that increase their ability to deliver aircraft that meet scheduled times of arrival (STAs) at CSPs more precisely. When TBFM-assigned delays are larger than what can be accommodated through speed adjustments alone, controllers are presented with advisories that include closed-loop path stretch maneuvers to help absorb needed delay. These advisories reduce the use of tactical vectoring and holding to absorb larger delays, and enable delay to be taken at higher altitudes, often prior to Top-of-Descent (ToD), where aircraft perform more efficiently and bum less fuel. Advisory solutions may span several sectors along a flight's trajectory and will likely require verbal coordination with downstream sectors. This is a change from the current metering paradigm where individual sectors are each responsible for working off a portion of the total TBFM-assigned delay in a segmented, and potentially less efficient, manner.

5.3.3 Terminal Sequencing and Spacing

Terminal Sequencing and Spacing extends scheduling and metering capabilities into the terminal area and provides metering automation tools to terminal controllers and terminal traffic managers. Those controllers and traffic managers become active participants in time-based metering operations as they work to deliver aircraft accurately to CSPs within terminal airspace and to the runway in accordance with scheduled times at those points. A higher level of coordination takes place with the overlying center regarding the overall metering operation.

Terminal controllers are better able to support and enable improved operations, such as Required Navigation Performance (RNP), through tools that support the merging of mixed-equipage traffic flows (such as merging aircraft flying RNP and non-RNP procedures). Terminal traffic managers have improved situation awareness through the use of displays that allow for the monitoring of terminal metering operations, similar to the displays used today by center traffic managers to monitor En Route metering operations.

5.3.4 Expanded Deployment of Integrated Departure Arrival Capability TBFM WP3 expands the deployment of the IDAC, begun under WP2, to the remaining fifteen centers and additional airports. This enables Tower (or in some cases terminal) controllers at these additional facilities to use automation to assign departure times to flights that correspond to available slots in the overhead flow, improving on what was largely a manual and time-consuming process.

5.4 TBFM Functional Decomposition

TBFM WP3 capabilities are part of the larger NAS Enterprise Architecture hierarchy where they are denoted as "Derive Flow Management Schedules," as described in the TBFM Enterprise Architecture products [Sekhavat-Tafti et al., 2012]. Therefore, that name is used throughout this document for the top-level function in this TBFM WP3 functional analysis.

The high-level functions for TBFM WP3 reflect the type of constraint being considered and the types of function being performed for that constraint, as shown in Table 5-1. In addition to the types of constraints described in Section 5.2, the Terminal Sequencing and Spacing capabilities

5-9 described in Section 5.3.3 need an additional type of constraint to reflect where metering will be done within terminal airspace, referred to hereafter as "Terminal Constraints."

Table 5-1. Relationship of High-Level Functions to Constraint and Function Types

' Type pf Function ' ''" " ) a

Type of Constraint Sequencing ' ) Scheduling and Oei:onfliction '

En Route 1: Sequence Flights To En Route Constraints

2: Schedule Flights To En Route Constraints

Arrival 3: Sequence Flights To Arrival Constraints

4: Schedule Flights To Arrival Constraints

Runway 5: Sequence Flights To Runway Constraints

6: Schedule Flights To Runway Constraints

Terminal 7: Sequence Flights To Terminal

8: Schedule Flights To Terminal

Each of the functions listed in the table are described at a high level following the functional hierarchy diagram in Figure 5-5. The functional hierarchy is depicted using functional symbology defined in the NAS SEM [FAA, 2006]. Each rectangle contains the title of the function in the center. A unique number is located above the horizontal line at the top of the rectangle. This number will be used to reference this function in the FFBDs and N2 diagrams in the appendices.

The high-level functions are then shown decomposed into sub-functions in subsequent sections, as follows:

1. Sequence Flights To En Route Constraints: Section 5.4.l

2. Schedule Flights To En Route Constraints: Section 5.4.2

3. Sequence Flights To Arrival Constraints: Section 5.4.3

4. Schedule Flights To Arrival Constraints: Section 5.4.4

5. Sequence Flights To Runway Constraints: Section 5.4.5

6. Schedule Flights To Runway Constraints: Section 5.4.6

7. Sequence Flights To Terminal Constraints: Section 5.4.7

8. Schedule Flights To Terminal Constraints: Section 5.4.8

While the functions sound quite similar at this level of detail, the differences are more apparent at the detailed functional and algorithmic levels that will be described in documents produced later in the acquisition process.

For Functions 2 and 4, an additional level of detail is provided for one sub-function each, in order to show the functional impact of the Path Stretching capabilities on the generation of controller advisories.

5-10

Figure 5-5. TBFM "To Be'' Functional Hierarchy

5.4.1 Function 1: Sequence Flights To En Route Constraints

This function determines the flights to which each en route constraint-known as a "Meter Point"-applies, then builds the trajectory to the appropriate meter point for each flight. The order in which flights are expected to reach each en route constraint is also determined by calculating the expected time of arrival (ETA) for each of those flights and applying any controller-entered sequencing changes. This function also identifies whether a flight's trajectory will intersect with known and forecast weather avoidance areas between its current position and the meter point. This function will calculate a nominal path that models the predicted deviation of the flight around the weather and will calculate an updated ETA and trajectory' for the flight based on the deviation path. This function is decomposed into five functions as show in the functional hierarchy in Figure 5-6 and the FFBD in Figure 5-7.

2 The calculated deviation trajectory is not intended to be issued as a reroute. This deviation trajectory is only calculated to generate an updated ETA that seeks better approximate the meter fix crossing time that will result if the pilot deviates.

5-11 with MREs and Super Stream

Point

Figure 5-6. Sequence Flights To En Route Constraints Hierarchy

Figure 5-7. Sequence Flights To En Route Constraints FFBD

5.4.1.1 Function 1.1: Correlate Flight with MREs and Super Stream Class for Meter Point This function uses flight-specific data such as the route of flight and the aircraft type to correlate the flight to a meter point and super stream class. A super stream class is a grouping of stream classes with similar scheduling characteristics, while stream classes are groupings of individual flights with similar scheduling characteristics (e.g., engine type, destination airport, assigned meter point). This function will also correlate the flight with MREs used for delay allocation along the flows feeding the meter point.

MREs and super Stream Class for

Meter Point

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5.4.1.2 Function 1.2: Build Flight Trajectory to Meter Point

This function uses the flight plan (route of flight, aircraft type, etc.) to build a detailed path to the meter point that is flyable by the aircraft via a series of waypoints, constructs a four-dimensional trajectory to the meter point for each flight path based on data including aircraft type models and wind forecasts, and calculates ETAs along the four-dimensional trajectory for each flight. ETAs are calculated to the meter point as well as to MREs used for delay allocation along the flows feeding the meter point.

5.4.1.3 Function 1.3: Model Weather Deviation for Meter Point This function determines whether a flight's trajectory will intersect with known and forecast weather avoidance areas' between its current position and the meter point. When such an intersection is detected, this function calculates a nominal path' that models the predicted deviation of the flight around the weather avoidance area, calculates an updated ETA for the flight based on that deviation path, and provides the updated ETA (flagged as resulting from a weather deviation prediction) and the trajectory incorporating the nominal deviation path. When no such intersection is detected, this function forwards the current trajectory, including its associated ETA at the meter point.

5.4.1.4 Function 1.4: Generate Sequence of Flights at Meter Point This function builds and updates the sequence of flights through the meter point based on the calculated ETAs. The sequence is developed by ordering the flights from earliest ETA to latest and applying the appropriate, pre-defined tie-breaking rules.

5.4.1.5 Function 1.5: Process Meter Point Sequence Override

This function allows controllers and traffic managers to swap flights within a meter point sequence.

5.4.2 Function 2: Schedule Flights To En Route Constraints

This function assigns times at which flights should cross each en route constraint meter point, based on their order in the sequence and the spacing needed to meet the constraint parameters at the meter point and at any coupled metering fixes. It also calculates the delay each flight needs to absorb by the meter point to meet the assigned time, generates advisories about how to absorb that delay with speed changes and possibly path stretch maneuvers, and calculates departure times for flights that are still on the ground. In addition, it allows traffic managers to specify which meter points' meter lists will be provided for display to controllers. This allows traffic managers to select the meter points for which controllers will enforce delay. This function is decomposed into nine functions as show in the functional hierarchy in Figure 5-8 and the FFBD in Figure 5-9.

3 These weather avoidance areas will likely be provided by a yet to be defined external system.

4 The calculated deviation trajectory is not intended to be issued as a reroute. This deviation trajectory is only calculated to generate an updated ETA that seeks better approximate the meter fix crossing time that will result if the pilot deviates.

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Figure 5-8. Schedule Flights To En Route Constraints Hierarchy

Figure 5-9. Schedule Flights To En Route Constraints FFBD

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5.4.2.1 Function 2.1: Assign Meter Point Crossing Times to Flight This function assigns an STA at the meter point for each flight based on the ETA from the current trajectory, information from upstream and downstream MPs or MPs, and restriction parameters (e.g., miles-in-trail spacing, a rate) to be met at the meter point.

5.4.2.2 Function 2.2: Assign Delay per Flight for Meter Point This function calculates the delay to be absorbed per flight by subtracting each flight's meter point ETA from the meter point STA.

5.4.2.3 Function 2.3: Allocate Delay Absorption by Flight for Meter Point This function calculates the delay to be absorbed between each pair of meter reference elements (MRE) associated with the meter point (e.g., the outer-outer point and the outer point, the outer point and the meter point).

5.4.2.4 Function 2.4: Provide Current Delay Information to Upstream Schedules for Meter Point This function coordinates the meter point schedule with linked upstream meter point schedules by passing back the delay for each flight that is needed to meet the downstream meter point constraint and cannot be absorbed between the two meter points for that flight. This passback delay is used to adjust the linked upstream meter point schedule such that constraints at both meter points will be met.

5.4.2.5 Function 2.5: Provide Current Delay Information to Downstream Schedules This function coordinates the meter point schedule with a coupled downstream meter fix schedules by passing along a weighted ETA at the meter fix for each flight. This weighted ETA is used to account for the delay to be absorbed by each flight at the meter point.

5.4.2.6 Function 2.6: Generate Controller Advisories for Meter Point This function calculates speed and path adjustments so that each flight will achieve its STA at each of its meter points. This function checks the adjustments for conflicts, modifying the adjustment to avoid conflicts if possible. This function provides those adjustments as advisories to be displayed to the active controller for the flight.

An additional level of detail is provided in Figure 5-10 and Figure 5-11 for the sub-function 2.6, "Generate Controller Advisories for Meter Point," in order to show the functional impact of the Path Stretching capabilities on the generation of controller advisories.

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Determine Need for

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Figure S-10. Generate Controller Advisories for Meter Point Hierarchy ffbd Generate Controller Advisories for Meter Point

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Figure S-11 Generate Controller Advisories for Meter Point FFBD

5.4.2.6.1 Function 2.6.1: Determine Need for Meter Point Advisory This function determines whether a flight is eligible for advisories based on criteria such as whether the flight's STA is frozen, and whether it is at least a specified parameter distance from its top of descent point. For eligible flights, this function compares the allocated delay at a meter point with an adapted threshold parameter to determine whether the flight complies with its STA.

When the allocated delay exceeds the parameter, the function passes the needed delay to the next process. When the allocated delay does not exceed the threshold, this function passes on the need

5-16 to generate an advisory showing the speed the flight should maintain to the next meter point. In all cases, this function provides each flight's allocated delay for display to controllers on the appropriate meter lists.

5.4.2.6.2 Function 2.6.2: Evaluate Trajectory Changes to Meet Meter Point Constraints This function generates options for adjusting a flight's route and speed so that the allocated delay for the resulting provisional trajectory is within the threshold parameter. When allocated delay can be adequately addressed with speed adjustments, this function generates cruise and descent speed options taking into account the speed performance envelope of the flight's aircraft type.

When speed adjustments alone are insufficient to absorb the allocated delay, this function builds provisional route options that extend the lateral path of the flight's route (i.e., path stretch) to allow for longer path lengths, and thus longer flight times, combined with a speed adjustment as needed to meet the flight's STA. The process iterates until an adjustment with a provisional trajectory that adequately meets the STA is found or all options have been exhausted.

5.4.2.6.3 Function 2.6.3: Detect Conflicts in Provisional Meter Point Trajectories This function checks the provisional trajectory for aircraft-to-aircraft conflicts and aircraft-to-airspace conflicts.

5.4.2.6.4 Function 2.6.4: Avoid Conflicts in Provisional Meter Point Trajectories This function revises the provisional trajectory to resolve all detected aircraft-to-aircraft conflicts and aircraft-to-airspace conflicts, by adjusting speeds and/or lateral path stretch maneuvers while still satisfying the meter point constraint. The revised adjustment is provided for display as an advisory to the appropriate controller, including a warning when there were any conflicts that could not be resolved while still meeting the flight's STA.

5.4.2.7 Function 2.7: Process Meter Point Schedule Override

This function allows a traffic manager to assign a meter point STA to a single flight or reschedule the STA for a single flight.

5.4.2.8 Function 2.8: Process Request for Departure Time to Meter Point This function processes an ARTCC traffic manager request to assign a departure time for a flight that will cross a meter point. The function assigns an STA to the meter point for the flight in question and then assigns a departure time corresponding to the STA. This function also allows traffic managers at a tower or TRACON to electronically request that an ARTCC traffic manager request a departure time for a specific flight.

5.4.2.9 Function 2.9: Process Request to Update Meter List Distribution to Controllers This function allows traffic managers to specify which meter points' meter lists will be provided for display to controllers.

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Correlate fllght With MREs and Super Stream Class for

Meter FIX

Model Weather Deviation for Meter

Flx Generate Sequence

Date:

5.4.3 Function 3: Sequence Flights To Arrival Constraints

This function determines the flights to which each arrival constraint-known as a "Meter Fix"-applies, then builds the trajectory to the appropriate meter fix for each flight. The order in which flights are expected to reach each arrival constraint is also determined by calculating the estimated time of arrival (ETA) for each of those flights and applying any controller-entered sequencing changes. This function also identifies whether a flight's trajectory will intersect with known and forecast weather avoidance areas between its current position and the meter fix. This function will calculate a nominal path that models the predicted deviation of the flight around the weather and will calculate an updated ETA and trajectory' for the flight based on the deviation path. This function is decomposed into five functions as show in the functional hierarchy in Figure 5-12 and the FFBD in Figure 5-13.

hler Sequence Fhghts To Amva! Constraints

Sequence Flights To Arnva! Constraints

Figure 5-12. Sequence Flights To Arrival Constraints Hierarchy

5 The calculated deviation trajectory is not intended to be issued as a reroute. This deviation trajectory is only calculated to generate an updated ETA that seeks better approximate the meter fix crossing time that will result if the pilot deviates.

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Figure 5-13. Sequence Flights To Arrival Constraints FFBD

5.4.3.1 Function 3.1: Correlate Flight With MREs and Super Stream Class for Meter Fix This function uses flight-specific data such as the route of flight and the aircraft type to correlate the flight to a meter fix and super stream class. This function will also correlate the flight with meter reference elements (MREs) used for delay allocation along the flows feeding the meter fix.

5.4.3.2 Function 3.2: Build Flight Trajectory to Meter Fix

This function uses the flight plan (route of flight, aircraft type, etc.) to build a detailed path to the meter fix that is flyable by the aircraft via a series of waypoints, constructs a four-dimensional trajectory to the meter fix for each flight path based on data including aircraft type models and wind forecasts, and calculates ETAs along the four-dimensional trajectory for each flight. ETAs are calculated to the meter fix as well as to MREs used for delay allocation along the flows feeding the meter fix.

5.4.3.3 Function 3.3: Model Weather Deviation for Meter Fix

This function determines whether a flight's trajectory will intersect with known and forecast weather avoidance areas' between its current position (or previous CSP) and the meter fix. When such an intersection is detected, this function calculates a nominal path' that models the predicted deviation of the flight around the weather avoidance area, calculates an updated ETA (flagged as resulting from a weather deviation prediction) for the flight based on that deviation path, and provides the updated ETA (flagged as resulting from a weather deviation prediction) and the

6 These weather avoidance areas will likely be provided by a yet to be defined external system.

7 The calculated deviation trajectory is not intended to be issued as a reroute. This deviation trajectory is only calculated to generate an updated ETA that seeks better approximate the meter fix crossing time that will result if the pilot deviates.

5-19 trajectory incorporating the nominal deviation path. When no such intersection is detected, this function forwards the current trajectory, including its associated ETA at the meter fix.

5.4.3.4 Function 3.4: Generate Sequence of Flights at Meter Fix This function builds and updates the sequence of…