t o on ept - sesar joint undertaking...that run in parallel (aom, dcb, ao, ts, cm and auo), together...

Version: Appendix A to WP-xxx - TBOCD 3.0 Saved: 17/02/2015 11:03 1/50

TBO CONCEPT

BY THE ICAO ATMRPP


Contents

Summary ................................................................................................................................................................. 4

1 INTRODUCTION .............................................................................................................................................. 7

1.1 Background ........................................................................................................................................... 7

1.2 Purpose/objective ................................................................................................................................. 7

1.3 Scope ..................................................................................................................................................... 7

1.4 Target audience .................................................................................................................................... 7

1.5 Document organisation ......................................................................................................................... 7

1.6 Relationship to other documents ......................................................................................................... 8

1.7 Definitions ............................................................................................................................................. 8

1.8 Acronyms .............................................................................................................................................. 9

2 The need for TBO ......................................................................................................................................... 11

2.1 The problem space .............................................................................................................................. 11

2.2 Synchronizing information across stakeholders ................................................................................. 13

2.3 Ensuring consistency between trajectory constraints ........................................................................ 13

2.4 Integrating the airline perspective ...................................................................................................... 16

2.5 Residual unpredictability..................................................................................................................... 17

2.6 Evolution, not revolution .................................................................................................................... 20

3 Separation provision in TBO ........................................................................................................................ 21

3.1 Separation related definitions ............................................................................................................ 21

3.2 ATC clearances and instructions ......................................................................................................... 21

3.3 Closed loop clearances ........................................................................................................................ 23

3.4 Conflict horizon ................................................................................................................................... 23

3.5 Trajectory constraints and tolerances ................................................................................................ 25

4 Characteristics of TBO .................................................................................................................................. 26

4.1 Trajectory management loop .............................................................................................................. 26

4.2 Multi actor framework ........................................................................................................................ 28

4.3 Federated architecture ....................................................................................................................... 29

4.4 Integrating the aircraft’s FMS ............................................................................................................. 30


4.5 Performance based navigation ........................................................................................................... 31

4.6 Performance based trajectory prediction ........................................................................................... 31

5 The solution space ....................................................................................................................................... 34

5.1 Synchronizing the trajectory prediction .............................................................................................. 34

5.2 Include surface movements in trajectory prediction .......................................................................... 34

5.3 Closed loop vectoring .......................................................................................................................... 34

5.4 Time constraints .................................................................................................................................. 35

5.4.1 Time constraints in support of separation provision ...................................................................... 35

5.4.2 Time constraints in support of arrival management ...................................................................... 36

5.4.3 Time constraints in support of DCB ................................................................................................ 36

5.5 Altitude constraints ............................................................................................................................. 37

5.6 Improved climb and descend profiles ................................................................................................. 37

5.7 Pre-departure ranked trajectories ...................................................................................................... 37

5.8 Slot-Swapping (UDPP) ......................................................................................................................... 37

6 Agreeing trajectory changes ........................................................................................................................ 38

6.1 interdependencies between hot spots ............................................................................................... 38

6.2 Preferred solutions for conflict management enroute ....................................................................... 38

6.3 Prefered solutions for delay absorbtion in arrival phase .................................................................... 38

7 Globally Harmonized Information Exchanges .............................................................................................. 39

8 Transition and technical enablers (i-TBO) .................................................................................................... 39

8.1 Roadmap of technical enablers ........................................................................................................... 39

8.2 Mixture of TBO and non-TBO aircraft ................................................................................................. 39

8.3 Mixture of TBO and non-TBO ANSPs ................................................................................................... 39

9 Open issues .................................................................................................................................................. 40

10 References ................................................................................................................................................... 41

Appendix A – TBO specific requirements ............................................................................................................. 43

Appendix B – ICAO Doc 9882 ATM system requirements related to TBO ............................................................ 47


SUMMARY

As defined in ICAO’s Global ATM Operational Concept (GATMOC), the ATM system consists of the ATM

components Airspace Organization and Management (AOM), Demand/Capacity Balancing (DCB), Aerodrome

Operations (AO), Traffic Synchronization (TS), Conflict Management (CM), Airspace User Operations (AUO) and

ATM Service Delivery Management (ATM-SDM).

The number of flights crossing multiple congested airspace and aerodrome structures is increasing. This results

in more and more flights being subject to multiple limiting factors that may originate from various ATM

components from different regions along its intended flight path, or 4D-trajectory. Without a global concept

that aligns constraints1 originating from these limiting factors along the flight’s trajectory, incompatibility

2 in

trajectory and/or generic constraints may increasingly be expected to lead to non-optimum flight profiles and

instabilities in the ATM network.

Trajectory Based Operations (TBO) is the glue between these ATM components during tactical

planning and flight operations by synchronizing the view of the trajectory between different actors

and ensuring consistency between the trajectory and/or generic constraints that originate from the

various ATM components and the various regions that shape this trajectory.

Stability and consistency of the combination of the solutions proposed by various ATM components

that run in parallel (AOM, DCB, AO, TS, CM and AUO), together with an efficiently converging

coordination process to find this stable and consistent combination, are pre-requisites for a safe and

efficient ATM network. Predictability is key.

Unambiguous criteria for the prioritization of “issues” stemming from any of the ATM components and

order of preference in choosing between alternatives of their corresponding solutions, and

simultaneously, where required, an efficient coordination process, needs to be put in place to ensure a

stable, consistent and converging trajectory management system. The key question is how to take

trajectory and/or generic constraints from the various processes into account in modifying the

trajectory constraints, especially if the trajectory and/or generic constraints are incompatible.

The use of trajectory constraints should be minimised to the extent possible and to the tolerance level

commensurate with the ATM function it serves, to avoid limiting airborne operations more than is

strictly required.

By synchronizing the expected remainder of the trajectory and its trajectory constraints (with tolerance levels)

for a flight between all involved ATM stakeholders, these have the awareness to better anticipate and respond

on the events that may impact them. As continuous synchronisation is impossible due to the limitations of

available communication budgets and network bandwidth, the sharing, updating and coordinating of

trajectory changes has to be sufficiently frequent to serve the reliability needs from the various ATM

components.

1 In the context of this paper, a constraint is an expression of limitation to free manoeuvring of an aircraft.

Limitations are geospatial and temporal of nature and can originate from any ATM component, as well as from

meteorological conditions or local regulations. A constraint can either be a trajectory constraint or a generic

constraint. See section 1.8 for a full definition.

2 Trajectory constraints cannot be inconsistent; they merely restrict the degree of freedom for a trajectory. If

simultaneous satisfaction of two trajectory constraints lies outside the possible flight envelope (“is not flyable”)

they are incompatible. In such cases these constraints may either combine their effect (feasibility depends on the

function they serve) or another solution avoiding these constraints is required.


With improved data communications for synchronizing information and its updates amongst the various

operational actors and systems, and with the introduction of improved performance based navigation, the

level of uncertainty is reduced substantially. However, the ATM network will never become fully deterministic;

some level of inherent unpredictability will remain.

The trajectory management concept needs to be resilient to changing circumstances and shall provide

the means to deal with residual unpredictability (“fine-tuning” the trajectory). Increasing performance

of the overall system is therefore not simply a matter of freezing a plan and ensuring that all aircraft

follow that plan. It requires planned trajectories to be continuously refined and revised during both

pre-departure and flight-execution phase, based on latest data, observations and predictions, in order

to continuously find the optimum balance between sometimes conflicting demands from different

stakeholder perspectives: the flight itself; the airlines; the ATM network; and Air Traffic Services.

Trajectory Based Operations (TBO) defines how and to what extent to include airspace users into the

optimization process, balancing flexibility for prioritization and optimizing airspace users operations

while simultaneously ensuring sufficient predictability needed to optimize the ATM network as a whole

and ensuring that the flight safety is never compromised.

Clearances will allow the incremental refinement of the trajectory by the ATM system. Therefore, although the

flight deck and the ATM system will have entered into a “gate-to-gate”3 coordinated trajectory prediction, that

coordinated trajectory intention only serves as input for a stepwise ATC clearances, which may be preceded by

a trajectory revision, for the portion of the trajectory that lies within the conflict horizon..

Consequently, under trajectory-based operations, clearances continue to be the mechanism through

which the ATC system exercises control over a flight’s trajectory. However, TBO does change the form

and means of communication of ATC clearances and instructions. Additional clearance types to those

available today will be available in the TBO environment. These go beyond simple instructions and are

targeted to become the principal revision means on the whole trajectory.

When unpredictability grows to the order of magnitude of the applicable separation criteria there is no

point in further de-conflicting individual trajectories. However, it is possible to extend the conflict

horizon, by adding one or multiple trajectory constraint(s) for separation purposes, reducing residual

unpredictability.

Improving the reliability of trajectory prediction requires vectoring to be “closed loop” style. This can

be achieved through the use of the elastic vector concept, which allows controllers to register in the

system how they plan to close an open-loop vector. In TBO, it is possible to uplink elastic vectors to the

aircraft. It shall be possible to either uplink an elastic vector and a clearance to proceed according to

the elastic vector in a single uplink command, or uplink the elastic vector as a plan, to be followed by

the actual clearance at a later stage.

The management of trajectories in the dynamic ATM environment is a control loop consisting of monitoring of

the various ATM functions against their objectives, detecting any “issues”, stemming from any of the GATMOC

ATM components in any of the regions, that require action, generate solutions either through changing a local

or regional ATM configuration (“major issue” impacting many trajectories; e.g. re-sectorization or different

runway combination) or through adding or changing trajectory constraints (“minor issue” impacting one or

several individual trajectories) possibly leading to a trajectory revision.

3 Instead of “gate-to-gate”, reference could equally well be made to “enroute-to-enroute” trajectories to

emphasize that the connection between departure and arrival is just as essential.


A coordination process, based on clear decision criteria and supported by automation, are required to

orchestrate the interaction between all stakeholders, ensuring stability and convergence of the ATM network.

Refinement on rules of interaction between operational stakeholders, involved through the various ATM

functions is required. The TBO concept specifies stakeholder’s roles and responsibilities to manage

(“ownership”) or contribute to the coordination of trajectory changes.

The ATM functions are distributed over many different ANSPs that act as one ATM system that is built through

a federated architecture. The architecture in support of TBO seamlessly aligns with this federated architecture

which also eases the integration of Airports, FOC and FMS into the federated ATM system.

Even a federated architecture requires trust amongst the contributing parties. The performance of

trajectory predictions need to be trustworthy and harmonized to be adequately accurate and reliable

for the ATM component they serve. This has to be independent of the stakeholder that provides them.

The trajectory constraints imposed to a flight must be trustworthy as being based on and compliant

with globally agreed principles and traceable to commonly known environmental limitations. All

actors applying changes to a trajectory must be trustworthy in supporting compliancy with the

trajectory constraints, and the aircrafts navigational capabilities must be trustworthy to be able to

adhere to these trajectory constraints to the tolerance level required.

A key role is for the downlinked FMS trajectory prediction during flight-execution (and the FOC

trajectory prediction in the pre-departure phase) indicating the level of compliance to all coordinated

trajectory constraints, as this closes the trajectory management loop. It provides verification on the

feasibility and synchronization of both trajectory and generic constraints (and the resulting trajectory

prediction) between ground and airborne systems.

Regarding navigational capabilities and trajectory prediction, a performance based approach is the

way to establish this required trust.


1 INTRODUCTION

1.1 BACKGROUND

TBD

1.2 PURPOSE/OBJECTIVE

TBD

1.3 SCOPE

TBD

1.4 TARGET AUDIENCE

TBD

1.5 DOCUMENT ORGANISATION

Chapter 2, 3 and 4 identify requirements on the TBO concept itself, starting with the need for TBO (chapter 2),

explaining its relation to separation management (chapter 3) and characterising TBO (chapter 4).

In all sections from chapters 2, 3 and 4 requirements from ICAO doc 9882 (ATM systems requirements in

support of the Global ATM Operational Concept) that may be related to the TBO concept have been identified.

At the end of each section in these first chapters, from the text any new formal requirements are captured.

Doc 9882 R xx.xx Various reviewers have commented on the requirements from doc 9882. Since these requirements are copied from an external reference (doc 9882) they cannot be changed within this document. Requirements copied from doc 9882 are highlighted with light blue as a reminder of this. Note: Requirements from doc 9882 are built on the assumption that a “4-D trajectory contract” will be established for all phases of flight. As a consequence, a number of doc 9882 requirements (R43, R73, R80, R82, R87, R98) are incompatible with the TBO concept as refined in this paper. Doc 9882 may require an update to reflect this.

Table 1 – Format of requirements from ICAO doc 9882 to TBO

TBO-CD R xx.xx Requirements that drive the definition of the TBO concept itself are marked yellow and shall be removed once the TBO is finalized.

Table 2 – Format of requirements on the TBO concept itself

An overview of both types of requirements is provided in Appendices A and B. These requirements drive the

content of the following chapters and serve as a cross check for the correctness and completeness of the TBO

concept itself.


Chapter 5 describes the elements that build the solution space. Chapter 6 describes how these elements will

work together and defines how to agree on changes to trajectory constraints. Chapter 7 describes the

transition path towards global TBO. It contains a roadmap of technical enablers and describes how to deal with

mixed equipage aircraft (TBO and non-TBO) and mixed equipped ANSPs (TBO and non-TBO).

Note that chapters 5, 6 and 7 are not intended to be mature for the ATMRPP in March 2015..

1.6 RELATIONSHIP TO OTHER DOCUMENTS

This document builds on the requirements identified in the Global ATM Operational Concept (GATMOC),

defined in ICAO Doc 9854 and the related ATM system requirements, defined in ICAO doc 9882. It builds on

many ICAO ATMRPP working papers provided by various members, as well as on material stemming from

FAA’s 4D Trajectory Based Operations (4D TBO) Concept of Operations (CONOPS) and SESAR’s ATM target

concept , CONOPS of Operations step 1 and 2 and SESAR Trajectory Management Framework Technical Note.

1.7 DEFINITIONS

4-Dimensional Trajectory (4DT)

The 4-Dimensional Trajectory consists of a set of points in space-time that describes the most likely path of an

aircraft. Each of these points has a defined level of inaccuracy and unpredictability in space and time.

ATM configuration

An ATM configuration is the sum of all factors that can influence ATC capacity. Controlling factors include

military airspace reservations and releases, sector configurations, runway combinations and runway usage.

ATM network

The ATM network is considered as a series of nodes, including all stakeholders on the ground and in the air,

providing or consuming information relevant for them [ICAO doc. 9965, P.5-1, 4.1.2 Line 3-4]. It acts as a

federated system of all ATM systems worldwide that are interconnected through the flights that they share.

Coordinated trajectory intention

A prediction of a 4-Dimensional Trajectory, that is compliant with the trajectory constraints imposed upon it,

and where these trajectory constraints have been coordinated amongst relevant operational stakeholders.

Constraint

An expression of limitation to free manoeuvring of an aircraft. Limitations are geospatial and temporal of

nature and can originate from any ATM component, as well as from meteorological conditions or local

regulations. A constraint can either be a trajectory specific constraint or a generic constraint.

Trajectory constraint

A trajectory constraint targets a specific trajectory and limits the freedom of a trajectory by fixing one

of its 4D points in one or more dimensions (vertical, lateral, time), with a corresponding tolerance

level (“between boundary values”) or direction (“before”, “after”, “above”, etc.)

Generic constraint

A generic constraint consists of known static or dynamic information that limits the solution space for

meeting trajectory constraints. Examples include aeronautical information like predefined airspace

structures, availability of military airspace for civil use, availability of conditional routes, night curfews,

etc.


Elastic vector

The air traffic controller who has issued a heading clearance will usually have a reasonably accurate plan in

mind as to how he will clear the flight to resume own navigation, i.e. re-join the initially intended flight path.

The elastic vector is the operational concept for describing the action of a controller entering this plan into the

ATC systems. The elastic vector enables that the controllers plan is visible to all actors. Even when the elastic

vector is used, controllers still need to close the loop by actually issuing the clearance for the aircraft to

resume own navigation.

GATMOC ATM components

The ATM system consists of the ATM components Airspace Organization and Management (AOM),

Demand/Capacity Balancing (DCB), Aerodrome Operations (AO), Traffic Synchronization (TS), Conflict

Management (CM), Airspace User Operations (AUO) and ATM Service Delivery Management (ATM-SDM).

1.8 ACRONYMS

ANSP Air Navigation Service Provider

AO Aerodrome Operations

AOM Airspace Organization and Management

ASP ATM Service Provider

ATM Air Traffic Management

AUO Airspace User Operations

CDM Collaborative Decision Making

CM Conflict Management

CPDLC Controller Pilot Data Link Communications

CTA, CTO Controlled Time of Arrival, Controlled Time Over

DCB Demand and Capacity Balancing

E-AMAN Extended Arrival Management

EPP Extended Projected Profile, downlinked FMS trajectory prediction

FIXM Flight Information Exchange Model

FF-ICE Flight and Flow in a Collaborative Environment

FL Flight Level

FMS Flight Management System

FOC Flight Operations Centre

FRT Fixed Radius Turn

GATMOC Global ATM Operational Concept

ICAO International Civil Aviation Organization

MET Meteorology

MTCD Medium Term Conflict Detection

PANS Procedures for Air Navigation Services

PBN Performance Based Navigation

PSAP Performance Service Assets Package

RNAV Area Navigation

RNP Required Navigational Performance

RTA/RTO Required Time of Arrival / Required Time Over(a waypoint)

SDM Service Delivery Management

SEP Separation Management

SID Standard Instrument Departure

STAR Standard Arrival Route


STCA Short Term Conflict Alert

SWIM System Wide Information Management

TBO Trajectory Based Operations

TBO-CD TBO concept document

TMA Terminal Manoeuvring Area

TS Traffic Synchronization

TTA, TTO Target Time of Arrival, Target Time Over

UDPP User Driven Prioritisation Process


2 THE NEED FOR TBO

2.1 THE PROBLEM SPACE

As defined in ICAO’s Global ATM Operational Concept (GATMOC) and illustrated in figure 1, the ATM system

consists of the ATM components Airspace Organization and Management (AOM), Demand/Capacity Balancing

(DCB), Aerodrome Operations (AO), Traffic Synchronization (TS), Conflict Management (CM), Airspace User

Operations (AUO) and ATM Service Delivery Management (ATM-SDM).

Figure 1 – The ATM components according to the GATMOC

ATM-SDM ensures coherency between these components that is supported by Collaborate Decision Making

(CDM) principles. The strategic objective is that the ATM community establishes a shared planning method

that seeks to better synchronize co-evolution of capabilities and thus optimize the delivery of performance

improvements. It seeks to balance the so called Performance Service Assets Package (PSAP).

Figure 2 – Lifecycle of trajectory; the glue between GATMOC’s ATM components

Trajectory Based Operations (TBO) is ATM-SDM during pre-tactical (operational planning) and tactical phases

(flight operations). It acts as the glue between the other six ATM components4 by synchronizing the trajectory

prediction and ensuring consistency between the trajectory and/or generic constraints that originate from the

4 Collision Avoidance is part of the Global ATM Operational Concept, but it is not depending on TBO as it

requires functional and technical independence of the other components.

AOM DCB AO TS CM AUO

Collaborative decision making ATM Service delivery management Airspace organization and management Demand/capacity balancing Aerodrome operations Traffic synchronization

CDMATM SDMAOMDCBAOTS

Conflict management* Strategic conflict management* Separation provision (SEP)* Collision avoidance

Airspace user operations Trajectory based operations

CM

AUOTBO

ATM SDM

CDM

Strategic and scheduling

Tactical planning

Flight operations

System Wide Information Management

ATM PLANNING PHASES

YEARS 6 MONTHS DAYS HOURS MINUTES

LONG TERM MID TERM EXECUTION

TRAJECTORY COORDINATOR

AIRSPACE USER

NETWORK MANAGEMENT

ATC

TRAJECTORY STATUS

PRE-NEGOTIATION NEGOTIATION AGREED INTENT FINE TUNING


various ATM components and the various regions that shape this trajectory. Given that the overall scene has

been set by decisions during the strategic part of ATM-SDM, in particular the performance areas related to the

dynamic adaptability of the network are targeted during TBO (e.g. Flexibility, Predictability). It consists of a

coordination of four dimensional trajectory predictions and trajectory and/or generic constraints across all

involved operational stakeholders, during pre-tactical (operational planning) and tactical phases (flight

operations); i.e. during the last 24hours before flight arrival.

Note 1: Once free route is deployed, the TBO concept will have to be able to support it.

Note 2: TBO may enable the improvement of climb and descend profiles.

Relevant ICAO doc 9882 requirements

Doc 9882 R97a The ATM system shall ensure that performance forms the basis for all ATM system development;

Doc 9882 R97b The ATM system shall ensure that performance targets are defined, regularly reviewed and monitored

Doc 9882 R85 The ATM system shall treat performance as a whole, that is, considering all the ATM community expectations and their relationships;

Doc 9882 R188j The ATM system shall balance the expectations of the ATM community Explanatory Text: The ATM system will consider the trajectory of a vehicle during all phases of flight and manage the interaction of that trajectory with other trajectories or hazards to achieve the optimum system outcome with the minimal deviation from the user-requested flight trajectory, whenever possible. The ATM system will provide seamless service to the user at all times and will operate on the basis of uniformity throughout all airspace. Uniformity embodies both application of common ATM system rules and procedures across all airspace and use of common core, technical functionality in the systems used. It is not intended that this will establish an all-embracing requirement for identical equipment or systems, although minimizing system duplication or reducing equipment or systems needed to operate in a global ATM system environment is an obvious goal. It is intended that agreed required minimum levels of aircraft equipment, performance, and ATM system network capabilities will be matched by defined levels of service. It is intended that the ATM system should provide all users, at a minimum, the same level of access to runways and airspace when compared to a regionally agreed baseline year.

Doc 9882 (ATM SDM)

R71 The ATM system shall operate on the basis that the airspace user will provide flight and aircraft intent to the ATM system for use in planning and managing 4-D trajectories;

Doc 9882 (AUO)

R43 The ATM system shall provide, consistently with available ATM system resources, airspace users the capability to fly dynamic user-preferred 4D trajectories; Explanatory Text: It is expected that user-preferred trajectories will provide the most efficient flight operations and that the airspace users will provide these trajectories to the ATM system. These trajectories should be the key/core element of the (shared) information management. The expectation is that the global exchange of information (from individual aircraft performance up to ATM resources) should allow full use of 4-D trajectory management/operation. The expectation is that the 4-D trajectory management optimization could be a function of either the ground or the air or both.

TBO specific requirements

TBO-CD R2.1.001 Trajectory predictions shall be adequately synchronized between stakeholders

TBO-CD R2.1.002 Trajectory and/or generic constraints that shape a trajectory, originating from various GATMOC ATM components (AOM, DCB, AO, TS, CM, AUO) and the various regions, shall be consistent.

TBO-CD R2.1.003 The trajectory definition shall be able to support a free-route environment;


2.2 SYNCHRONIZING INFORMATION ACROSS STAKEHOLDERS

Building on System Wide Information Management (SWIM), FF-ICE and new capabilities for Air-Ground

trajectory exchange, ground and airborne actors and systems have access to adequately synchronized and up

to date flight information, meteorological information, airspace information and aerodrome information in

four dimensions, to the fidelity required to perform its functions. This already leads to an increased

predictability as a result of better network monitoring, earlier problem detection and wiser intervention.

By synchronizing the expected remainder of the trajectory, its trajectory constraints (with tolerance levels) and

its generic constraints, for a flight between all involved ATM stakeholders, these stakeholders increase their

awareness enabling them to better anticipate on the events that may impact them. As continuous

synchronisation is impossible due to the limitations of available communication budgets and network

bandwidth, the sharing, updating and coordinating of trajectory changes has to be sufficiently frequent to

serve the reliability needs from the various ATM components.

Operating in such an environment gives all stakeholders clear visibility of the trajectory with the lateral,

vertical or time trajectory and/or generic constraints that define it, as well as of the operational factors that

may affect it. This continuous sharing and updating is enabled by automation5.


Doc 9882 R187 The ATM system shall ensure that all information for performance management is available to the concerned parties transparently and that information disclosure rules are in place;

Doc 9882 R162 The ATM system shall be designed so that the operation and continued evolution of the ATM system incorporates mechanisms so that information and/or actions concerning emergency and/or unexpected events involving any of the airborne or ground-based ATM community members can be communicated to all ATM system participants who need to respond to or be aware of the event or actions;

Doc 9882 R70 The ATM system shall implement system wide information management

Doc 9882 (DCB)

R36d The ATM system shall utilize projected traffic demand and planned trajectories


TBO-CD R2.2.001 The quality of service of the synchronization of the expected remainder of the trajectory between stakeholders shall be commensurate with the required accuracy and reliability of the various ATM components to monitor compliance to the trajectory constraints - originating from such an ATM component - and their tolerance levels.

2.3 ENSURING CONSISTENCY BETWEEN TRAJECTORY CONSTRAINTS

With worldwide increasing air traffic volumes, there is a worldwide increasing need for effective measures to

ensure an efficient handling of traffic and to avoid congested airspace (“hotspots”) being overloaded beyond

safety limits6. Congestion or capacity reduction may have various causes: interfering airports in close

5 Automation does not always imply fully automatic – in the case of trajectory updating (revision), the human

will remain in the loop to send, receive and activate. In the case of trajectory information (sharing) a fully

automated system to system synchronisation is targeted.

6 Which would be avoided by applying DCB measures to safely manage the traffic load


proximity, convective weather, wind conditions changing runway configuration and/or capacity, reduced-

visibility, ground delays, conditional routes, temporary military airspace reservations, noise abatement

procedures, wake risk mitigation procedures, etc.

The number of flights crossing multiple congested airspace and aerodrome structures is increasing. This results

in more and more flights being subject to multiple limiting factors that may originate from different regions

along its intended flight path, or 4D-trajectory. This is illustrated in figure 3. Without a global concept that

aligns trajectory constraints originating from these limiting factors along the flight’s trajectory,

incompatibilities7 in trajectory constraints may increasingly be expected to lead to non-optimum flight profiles

and instabilities in the ATM network8.

The different ATM components of the GATMOC relate to various time-horizons of a trajectory prediction.

These functions all act on the same trajectory prediction (often on different parts of it) by adding or removing

lateral, vertical or time trajectory constraints, with or without accompanying tolerance levels. The trajectory

prediction, shaped by these trajectory constraints, is the common denominator for these ATM functions.

Figure 3 – Flights crossing multiple congested airspace and aerodrome structures

Adding or removing a trajectory constraint on one part of the trajectory may impact another part of the

trajectory; the ATM components interact with each other: While strategic conflict management (i.e. AOM, DCB

and TS) aims to ease the later separation provision, by doing so it may simultaneously complicate separation

provision further upstream by adding (time) trajectory constraints. Similar, further upstream separation

7Trajectory constraints cannot be inconsistent; they merely restrict the degree of freedom for a trajectory. If

simultaneous satisfaction of two trajectory constraints lies outside the possible flight envelope (“is not flyable”)

they are incompatible. In such cases these constraints may either combine their effect (feasibility depends on the

function they serve) or another solution avoiding these constraints is required.

8 For example, in Europe’s current operations flow control measures are applied on a regional basis. The only

control mechanism within its remit is to apply delay to flights departing from within the European region.

Inbound flights from outside Europe are exempt from these flow measures.

ESAFEastern and Southern Africa

WACAFWestern and Central Africa

NACCNorth American, Central American and Caribbean

SAMSouth America

APACAsia and Pacific

EUR/NATEuropean and North Atlantic

MIDMiddle East

+0 H +6 H +12 H +18 H +24 H

Time (to fly) to predicted trajectory part

Geo

grap

hic

al lo

cati

on

= Flight

= Hotspot

LEGENDA


provision may result in changing the trajectory and therefore its downstream trajectory prediction, possibly

resulting in not respecting the envisioned strategic conflict management plan.

For example an inbound aircraft which is at cruising level will be managed tactically in its current airspace for

separation provision while simultaneously being considered by extended arrival management (E-AMAN) for

the destination (extended) TMA.

Stability and consistency of the combination of the solutions proposed by various ATM components that run in

parallel (AOM, DCB, AO, TS, CM and AUO), together with an efficiently converging coordination process to find

this stable and consistent combination, are pre-requisites for a safe and efficient ATM network. Predictability

is key.

Figure 4 – Different ATM components acting on the same trajectory

Unambiguous criteria for the prioritization of “issues”9 and order of preference in choosing between

alternatives of their corresponding solutions needs to be put in place, simultaneously with an efficient

coordination process where required, to ensure a stable, consistent and converging trajectory management

system. The key question is how manage trajectory constraints from the various processes, especially if the

trajectory constraints are incompatible.


Doc 9882 (DCB)

R36g

The ATM system shall facilitate collaboration on trajectory changes and traffic demands

Doc 9882 (TS)

R87 The ATM system shall utilize the 4-D trajectory for traffic synchronization applications to meet the ATM system performance targets, unless under certain conditions other means are determined to be more effective; Explanatory text It is expected that flight plans will be replaced by 4-D trajectory contracts for all phases of flight. 4-D trajectory contracts will constitute a prerequisite for dynamic control of aircraft and vehicles. Negotiations will take place dynamically, as total awareness will be available to the complete ATM community. Agreed 4-D trajectories will increase predictability as well as reduce the need for current traditional path-stretching methodologies. It is expected that spacing between aircraft will be done through the use of 4-D trajectories, which will be updated and interacted upon collaboratively. The 4-D trajectories will be provided as 4-D trajectory contracts and will be modified and acted upon dynamically and according to at least the criteria defined by conflict management to create a safe and orderly flow of traffic. It is expected that spacing between aircraft will be done through the use of 4-D trajectories, which will be updated and interacted upon collaboratively. The 4-D trajectories will be provided as 4-D trajectory contracts and will be modified and acted upon dynamically and according to at least the criteria defined by conflict management to create a safe and orderly flow of traffic.


TBO-CD R2.3.001 The combination of the solutions proposed by various ATM components that run in parallel (AOM, DCB, AO, TS, CM and AUO) shall be stable and consistent;

TBO-CD R2.3.002 An efficiently converging coordination process shall be applied to find a stable and

9 Which could originate from AOM, DCB, AO, TS, CM and AUO

Arrival ManagementSeparation provision

Trajectory prediction

constraints constraints

Demand and Capacity Balancing

constraints


consistent combination of solutions proposed by the various ATM components;

TBO-CD R2.3.003 Unambiguous criteria shall be applied for the prioritization of AOM, DCB, AO, TS, CM and AUO problems and an order of preference shall be applied in choosing between alternatives of their corresponding solutions;

RBO-CD R2.3.004 The TBO concept shall define how to manage trajectory constraints from the various ATM components, especially if the trajectory constraints are incompatible;

2.4 INTEGRATING THE AIRLINE PERSPECTIVE

While ATM’s primary function is to enable the safe and expeditious handling of air traffic, a secondary

objective is to do so while optimizing the airspace user’s trajectories to the extent possible. While it may be

relatively straightforward how to optimize and prioritize coherent trajectories from one airline - e.g. by

identifying priority flights, based on inter flight dependencies due to linked airframe, crew and payload - it is

less obvious for a system that consists of flights stemming from multiple competing airline networks. Criteria

for optimization may vary not just between ANSPs and airlines, but also between different airlines.

The synchronization of information across all operational actors is a pre-requisite for TBO since it enables them

to anticipate many AOM, DCB, AO, TS, CM and AUO issues early on, including but not limited to possible

bottlenecks in separation provision. An early identification of issues increases the solution space for solving

them, enabling airspace users to optimize their operations to the extent possible within the limitations at hand

(“smoothing”).

The Flight Operations Centre (FOC) is a key stakeholder with full awareness of the attributes of each flight and

of the efficiency of the airline’s network. The roles of the FOC and its pilots will evolve through increased

automation support that enables them to be efficiently incorporated in the trajectory management loop. This

shift will take place in all domains of flight operations including pre-flight planning, surface, arrival and

departures, and enroute.

Trajectory Based Operations (TBO) defines how and to what extent to include airspace users into the

optimization process, balancing flexibility for prioritization and optimizing airspace users operations while

simultaneously ensuring sufficient predictability needed to optimize the ATM network as a whole and ensuring

that the flight safety is never compromised.


Doc 9882 R165 The ATM system shall ensure that, in the design of the ATM system, the principles of access and equity are taken into account; See also R188j in section 2.1

Doc 9882 R181 The ATM system shall implement and operate in such a way that the varying and diverse user requirements will be met as closely as technically possible within the defined equity and access;

Doc 9882 R07 The ATM system shall ensure that the airspace user makes available relevant, operational information to the ATM system;

Doc 9882 R08 The ATM system shall use relevant, airspace user operational information to optimize flight operation management;

Doc 9882 R27 The ATM system shall ensure that flight parameters and aircraft performance characteristics are available to the ATM system; Explanatory Text As is the case across the whole ATM system, in relation to aerodrome operations, the availability and exchange of information will facilitate management by trajectory. It is expected that the collaborative exchange process and respective facilities will allow for efficient management of air traffic flow through use of information on a system wide basis of air traffic flow, weather, and assets. This process will also allow, for example, allocation of entry/exit times for aerodromes and subsequent dynamic changes to mitigate for any imbalance.

Doc 9882 (ATM

R153 The ATM system shall operate on the basis that where there is a conflict between access and equity, allocation of priority to airspace users will be based on the


SDM) principle of maximizing ATM system performance; Explanatory Text: Existing practices relating to access and equity, particularly the “first come-first served” paradigm, should be amended to reflect the overall intent to improve ATM system performance. This is not intended to prohibit or block access to airspace; it is intended to allow establishment of procedures through collaborative decision making that optimize use of runways and/or airspace.

Doc 9882 (ATM SDM)

R98 Utilize flight trajectory, flight intent, and individual aircraft performance characteristics in providing ATM services; Explanatory Text: It is expected that the 4-D trajectory will be globally shared and used by the ATM community in all aspects of its operations. The requirement recognizes the difference between the tolerances associated with the 4-D contracts and what may be more stringent performance capabilities of the individual aircraft. For example, aircraft providing the ATM system with knowledge of their very accurate performance capabilities would, as a result, provide the ATM system opportunity to identify conformance/compliance irregularities that could be used in providing such services as conflict management, security notification/response, and so on.

Doc 9882 (AUO)

R44 The ATM system shall recognize and exploit airspace user capabilities to generate, negotiate, and adhere to user-preferred 4-D trajectories;

Doc 9882 (AO)

R27 The ATM system shall ensure that flight parameters and aircraft performance characteristics are available to the ATM system; Explanatory Text As is the case across the whole ATM system, in relation to aerodrome operations, the availability and exchange of information will facilitate management by trajectory. It is expected that the collaborative exchange process and respective facilities will allow for efficient management of air traffic flow through use of information on a system wide basis of air traffic flow, weather, and assets. This process will also allow, for example, allocation of entry/exit times for aerodromes and subsequent dynamic changes to mitigate for any imbalance.


TBO-CD R2.4.001 TBO shall define which airspace user operational information, flight parameters and aircraft performance characteristics need to be provided by the airspace user;

TBO-CD R2.4.002 TBO shall define how and to what extent to include airspace users, FOC and flight crew, into the process of trajectory changes, balancing flexibility for prioritization and optimizing airspace users operations while simultaneously ensuring sufficient predictability needed to optimize the ATM network as a whole;

TBO-CD R2.4.003 The flexibility needs from an individual Airspace User and the needs for predictability from the wider ATM network shall be balanced;

TBO-CD R2.4.004 TBO shall address pre-flight planning, surface, arrival and departures, and enroute operations;

TBO-CD R2.4.005 TBO shall describe the high level needs regarding “aeronautical information” which will allow the Airspace Users to better anticipate and respond and validate their operational choices depending on airspace characteristics.

2.5 RESIDUAL UNPREDICTABILITY

With improved data communications for synchronizing information10

and its updates amongst the various

operational actors and systems, with the introduction of improved performance based navigation, and through

improvements in the understanding of the atmosphere, the level of uncertainty is reduced substantially.

However, the ATM network will never become fully deterministic; some level of inherent unpredictability will

remain.

Because of wind and temperature forecast errors, or unpredictable weather events such as gusts,

ground and airborne predictions are subject to deviations. Deviations from forecasted gridded wind

10

Knowledge on actual flight parameters, like for example aircraft mass, may be as important as weather in the

uncertainty if that information is not available to a trajectory prediction (e.g. from ATC).


and temperature could be correlated with many aspects including height and the stability of the

atmosphere itself and as such these deviations vary in time. Particularly for medium and long haul

flights the longer time-horizon requires updates of meteorological information during flight execution

to reduce the difference between weather forecast and reality.

The turn-around process involves many actors, systems and planning functions which work towards a

shared common departure time. Elements of disturbance impacting the flight till take-off stem from

irregularities with security, passengers, fuelling, aircraft technical maintenance, baggage handling,

etc.

Not (yet) active (unarmed11

) clearances and actions not considered by the FMS in managed mode12

will continue to contribute to uncertainty for ground-based operational actors13

.

Air traffic behaves as a complex system, not just as a consequence of non-deterministic external

factors influencing execution (e.g. weather or passengers) as previously explained, but also because of

the high degree of interaction between many parallel operations: Individual flights interact with each

other as they share the same resources like airspace and runways (separation shall be assured) and air

traffic control (overload of sectors shall be avoided, complexity shall not exceed certain levels). A

change in one flight may affect many others.

A continuous synchronisation of information between all stakeholders is not technically feasible due to

bandwidth and communication cost limitations. An event driven update mechanism is required to

trigger actors and systems about updates when surpassing a predefined threshold level, based on

accuracy requirements for a specific ATM function. This includes for example the air-ground

synchronisation of the FMS trajectory prediction.

Trajectory based operations need to be resilient to these changing circumstances and shall be able to deal with

this residual unpredictability (“fine-tuning” the trajectory).

From an airline perspective, some level of flexibility is required in this trajectory management loop for

continuous optimization in an environment that contains residual unpredictability. From an ATM perspective,

a certain level of predictability of flight behavior is needed to ensure the required performance of the ATM

functions in support of these flights. There is, therefore, a need for a balance between the actual need of the

ATM system and the needs of individual airspace users.

Note that total adherence to an agreed trajectory end-to-end (gate-to-gate, or enroute-to-enroute) would

also require trajectory complete de-confliction e.g. prior to push back and all the way to docking the aircraft

again, as part of the negotiation phase. This makes end-to-end trajectory definition very complex and end-to-

end trajectory negotiation practically impossible.

Increasing performance of the overall system is therefore not simply a matter of freezing a plan and ensuring

that all aircraft follow that plan. It requires planned trajectories to be continuously refined and revised during

the execution phase, based on latest data, observations and predictions, in order to continuously find the

11

Arming a mode on the flight deck means allowing a mode to engage once the engagement conditions apply

12 Airbus terminology

13 During approach and final, flap settings, time for gear down and speed reduction schedule differ between

aircraft type, crew and other factors like for example aircraft weight. Cruise, climb and descend profiles may

differ, depending on airspace user policy and cost-index settings. This uncertainty may be reduced by sharing

company specific parameters with the ATM system, or by using the trajectory prediction from the FMS. What

remains unpredictable is what the aircraft will do if the pilot selects manual rather than managed mode. For

example a pilot may select a different speed.


optimum balance between sometimes conflicting demands from different stakeholder perspectives: the flight

itself; the airlines; the airports, flow management; and ATC.

Three situations may occur:

1. Major deviations from a coordinated trajectory prediction occur and the earlier agreed TBO plan

needs to be adjusted. Major deviations can be caused by significant unpredicted weather changes,

unplanned runway closure, engine failure. Pre-departure deviations can be caused by irregularities

with security, passengers, fuelling, aircraft technical maintenance, baggage handling, etc. In those

cases trajectories may need to be re-planned and trajectory constraints need to be re-considered.

2. Minor deviations from a coordinated trajectory prediction (e.g. due to deviation from a weather

prediction) occur in reality, but the ATM network does not experience any problem because the

tolerance levels of the trajectory and/or generic constraints (“sensitivity threshold”) are wide enough

to allow this variation. The updated trajectory prediction will be synchronized, but there is no impact

on the trajectory constraints.

3. Minor deviations from a coordinated trajectory prediction (e.g. due to deviation from a weather

prediction) occur in reality and the aircraft needs to re-adjust through a loop of continuous corrections

to ensure it meets the trajectory and generic constraints that has a too small tolerance to accept the

variation. The aircraft is capable to adjust its performance as a response, e.g. to the deviation from a

weather prediction, to meet the agreed TBO plan.


Doc 9882 R199 The ATM system shall minimize the impact of adverse weather on the total ATM system, so as to ensure that maximum throughput is generated in all meteorological conditions;

Doc 9882 R201 The ATM system shall enable all airspace users to adjust departure and arrival times and modify flight trajectories dynamically, where necessary renegotiating trajectory agreements, thereby permitting them to exploit operational opportunities as they occur;

Doc 9882 (DCB)

R36e The ATM system shall accommodate revisions to trajectory requests and resources status

Doc 9882 R202 The ATM system shall address the operational and economic cost-effectiveness of gate-to-gate flight operations from a single-flight perspective;

Doc 9882 R203 The ATM system shall modify the airspace user’s preferred trajectory: i. when required to achieve overall ATM system performance

requirements; and/or ii. collaboratively with the airspace user, in a manner that recognizes the

airspace user’s need for single-flight efficiencies


TBO-CD R2.5.001 TBO shall be resilient to changing circumstances and shall provide the means to deal with residual unpredictability.

TBO-CD R2.5.002 The trajectory prediction and trajectory constraints shall be continuously refined and revised during the execution phase, based on latest data, observations and predictions, in order to continuously find the optimum balance between sometimes conflicting demands from different stakeholder perspectives: the flight itself; the airlines; the ATM network; and Air Traffic Services.

TBO-CD R2.5.003 TBO shall allow as much as possible, to change the trajectory in a way that is optimal for the airspace users

TBO-CD R2.5.004 TBO shall define to what accuracy level airspace users shall be capable to meet trajectory constraints;

TBO-CD R2.5.005 TBO shall define how to coordinate and agree changes on trajectory constraints;


This includes both individual trajectory changes, as well as adjusting many trajectories simultaneously, triggered by a single event;

2.6 EVOLUTION, NOT REVOLUTION

The change required to implement TBO cannot be through revolution, as aviation involves too many actors to

change overnight.

It is essential that the experience can be accumulated in order to fine tune the complex processes

involved, and ensure their stability. Validation will never be able to address all possible situations

Technical solutions will not all be there in the immediate future and will not all be deployed

simultaneously.

It is expected that non-TBO and TBO operations will co-existent into the indeterminate future. It is

possible that not all the world will ever transition towards TBO.

o The TBO concept needs to be able to deal with a mixed equipage environment where some

aircraft may not be able to downlink the FMS trajectory prediction, or may not be capable of

adhering to trajectory constraints with the required accuracy.

o Although in an envisioned TBO concept all ANSPs may be assumed to be TBO compliant, in

reality flights should be expected to cross both TBO and non-TBO compliant ANSPs.


TBO-CD R2.6.001 TBO shall identify dependencies between technical enablers, in support of the development of a deployment roadmap;

TBO-CD R2.6.002 TBO shall be resilient against a mixed equipage aircraft environment;

TBO-CD R2.6.003 TBO shall be resilient against a mix of TBO compliant and non-TBO compliant ANSPs;

TBO-CD R2.6.004 TBO shall define aircraft capabilities in terms of types of trajectory constraints and required accuracy level that an aircraft shall be capable to adhere to;

TBO-CD R2.6.005 TBO shall clarify how the discrepancy between air and ground trajectory predictions will be handled


3 SEPARATION PROVISION IN TBO

3.1 SEPARATION RELATED DEFINITIONS

The following definitions are taken from ICAO’s GATMOC and doc 4444 (PANS-ATM). The TBO concept does

not require any change to these definitions.

Conflict is any situation involving aircraft and hazards in which the applicable separation minima may

be compromised.

Conflict horizon is the extent to which hazards along the future trajectory of an aircraft are

considered for separation provision.

Hazards that an aircraft will be separated from are: other aircraft, terrain, weather, wake turbulence,

incompatible airspace activity and, when an aircraft is on the ground, surface vehicles and other

obstructions on the apron and manoeuvring area.

Separation minima are the minimum displacements between an aircraft and a hazard that maintain

the risk of collision at an acceptable level of safety.

Separation mode is an approved set of rules, procedures and conditions of application associated

with separation minima.

Separation provision is the tactical process of keeping aircraft away from hazards by at least the

appropriate separation minima.

Air Traffic Control clearance14,15

is defined as an authorization of an aircraft to proceed under

conditions specified by an air traffic control unit.

Clearance limit is the point to which an aircraft is granted an air traffic control clearance.

3.2 ATC CLEARANCES AND INSTRUCTIONS

Conventional clearances and instructions

Before departure, IFR flights receive a departure clearance from the clearance delivery position at the

departure airport. This clearance contains the flight identification, a clearance limit, which is normally the

destination aerodrome, the assigned SID if applicable and the initial altitude or flight level (FL), if not already

contained in the SID. This departure clearance is to be considered an acknowledgement from the ATM system

that the flight plan has correctly been entered into the system, but does not constitute a clearance to proceed.

Flight crews having received a departure clearance, need subsequent clearances. Clearances and related

instructions may apply to enter, land on, take off from, hold short of, cross, taxi and backtrack on any runway.

After having received the clearance for take-off, the aircraft can take-off and proceed on its assigned SID and

climb to the initial altitude or flight level (FL) contained either in the SID or the departure clearance, unless

otherwise instructed. Once that initial altitude or flight level (FL) is reached, the aircraft can’t climb further

unless they receive an ATC clearance to climb. The 2D route can be followed by default after the last point in

14

For convenience, the term “air traffic control clearance” is frequently abbreviated to “clearance” when used in

appropriate contexts.

15 The abbreviated term “clearance” may be prefixed by the words “taxi”, “take-off”, “departure”, “en-route”,

“approach” or “landing” to indicate the particular portion of flight to which the air traffic control clearance

relates.


the SID (i.e. no clearance to proceed is necessary) all the way until the clearance limit at the destination

aerodrome. This clearance limit is usually the IAF, or the clearance limit specified at the STAR if the aircraft has

been assigned a STAR by ATC. Before the clearance limit, aircraft are expected to receive an explicit clearance

for approach from ATC, followed by a clearance to land from the tower at the destination airport.

This non-optimal default clearance is usually overruled. In support of a flight profile that is closer to the

optimum and to ensure separation throughout the flight, subsequent clearances and related instructions are

provided by ATC. These may involve route instructions, climb, descend or level instructions, heading and speed

instructions and transition level instructions. In such cases a clearance limit applies to the clearance, providing

the name of the appropriate significant point, or aerodrome, or controlled airspace boundary that limits the

scope of the clearance.

Clearances and instructions in a TBO environment

Management by trajectory involves the development of a coordinated trajectory intention to conduct /

support a trajectory that extends through all the physical phases of flight. Management by trajectory does not

mean that every aspect of a flight, including arrival profile, runway, taxi path and gate needs to be

predetermined and captured in detail in the agreement at the time of departure. The coordinated trajectory

intention and subsequent management of that intention will include the detail required by the traffic

management phases that the flight is subject to at the time it is agreed and when subsequent revisions are

made. Subsequent tuning may be required, for example, for separation purposes.

TBO allows for the incremental refinement of the trajectory by the ATM system. Therefore, although the flight

deck and the ATM system will have entered into a “gate-to-gate” coordinated trajectory intention, that

coordinated trajectory intention only serves as input for stepwise ATC clearances, which may be preceded by a

trajectory revision as required for separation purposes, for the portion of the trajectory that lies within the

conflict horizon.

Consequently, under TBO, clearances continue to be the mechanism through which the ATC system exercises

control over a flight’s trajectory. However, TBO does change the form and means of communication of ATC

clearances and instructions. Additional clearance types to those available today will be available in the TBO

environment. These go beyond simple instructions and are targeted to become the principal revision means on

the whole trajectory.


Doc 9882

(ATM SDM)

R72 The ATM system shall approve execution of 4-D trajectory agreements through

issuance of clearances;

Doc 9882

(CM)

R81 The ATM system shall determine the separator (read “the actor that will provide

separation”) for each renegotiated 4-D trajectory;

Doc 9882

(TS)

R182 The ATM system shall use 4-D trajectory control and/or flight deck delegation for

aircraft spacing;


TBO-CD R3.2.001 TBO shall clarify the difference between the coordinated trajectory prediction and

a clearance.

TBO-CD R3.2.002 TBO shall define the form and means of communication of ATC clearances and

instructions;

TBO-CD R3.2.003 TBO shall define which ATC can give a clearance at a given moment and for which

portion of the trajectory


3.3 CLOSED LOOP CLEARANCES

A closed-loop clearance is an ATC clearance resulting in the revision of one portion of the trajectory prediction;

for example, a direct route from a point on the original trajectory prediction to another point on the original

trajectory prediction. Open-loop clearances are heading or altitude related instructions that need to be closed

by a subsequent ATC instruction.

The air traffic controller who has issued a heading clearance will usually have a reasonably accurate plan in

mind as to how he will clear the flight to resume own navigation, i.e. re-join the initially intended flight path.

The elastic vector is the operational concept for describing the action of a controller entering this plan into the

ATC systems. The elastic vector enables that the controllers plan is visible to all actors. Even when the elastic

vector is used, controllers still need to close the loop by actually issuing the clearance for the aircraft to

resume own navigation.

The TBO concept is based on all actors having a common view of the trajectory. In this case, this would require

the elastic vector to be uplinked to the aircraft, so that air and ground both share the knowledge of how the

controller intends to close the open-loop vector. The controller’s elastic vector plan may involve certain pre-

requisites (e.g. another aircraft to leave a certain flight level or finish a turn) which may make it unsafe to

actually deliver the clearance to proceed according to the elastic vector, before the pre-requisites have

actually happened. As a consequence, in TBO the elastic vector uplink may or may not be combined with the

simultaneous uplink of a clearance to proceed according to the elastic vector.


TBO-CD R3.3.001 Elastic vector concept: The controller’s intent to make an aircraft re-join the

initially intended flight path after a vector instruction shall be registered and

visible to all actors;

TBO-CD R3.3.002 It shall be possible to uplink with a single data link command the elastic vector and

the clearance to proceed according to the elastic vector;

3.4 CONFLICT HORIZON

Due to the residual unpredictability, it cannot be assured that the predicted trajectory will remain free of

conflicts, even in the theoretical case that it would have been initially de-conflicted from all other trajectories

during flight preparation.

Figure 5 – The conflict horizon

The conflict horizon is the look-ahead time along the future trajectory of an aircraft that is considered for

separation provision. Different ground-system tools may operate with different look-ahead times, and

controllers may choose to look more or less time ahead depending on the sector where they work, their traffic

con

flic

t h

ori

zon

ATC clearance


Trajectory prediction=

Coordinated trajectory intention


load or even their individual preferences. Tactical separation tools typically operate with look-ahead times of 8

minutes or less. Medium Term Conflict Detection (MTCD) tools can look-ahead twenty or more minutes, but

such large horizons may be more useful for density-of-conflicts information to assess complexity rather than to

support separation provision for the actual conflicts they predict. As an example, a mere 2% uncertainty in

time in a 20 minutes horizon would translate into an uncertainty of 3.2 NM over the position of an aircraft

flying at 480KT. Uncertainty in the vertical dimension for larger conflict horizons may be even more challenging

because unlike the lateral flight path, vertical clearances are not by default (see section 3.2).

Trajectory constraint(s) may be used to reduce residual unpredictability (section 2.5), allowing separation

provision within an enlarged conflict horizon without the need for additional separation buffers. Nevertheless,

when time adherence trajectory constraints are used for bounding the uncertainty in time, new buffers are in

turn required to account for the limitations in the accuracy of the aircraft’s adherence capabilities. As an

example, time adherence with a +/- 10 seconds accuracy in a 20 minute-horizon would result in an uncertainty

in time of 20 seconds, which translates into an uncertainty in distance of 2.7 NM for an aircraft flying at 480

KT. This is a significant buffer in a 5 NM separation-minima environment.

The need for such separation buffers may be avoided by using closed-feedback loop processes to control the

execution of separation provision tasks. At each process loop, the crossing point becomes closer, and

therefore uncertainty over the future trajectory is reduced, and assessment of whether separation will actually

be safe becomes more reliable. At each process loop, further action can be taken to ensure safe separation if

deemed necessary. Close to the conflict point, uncertainty becomes negligible, and therefore in the last

process loop-cycles separation is guaranteed tactically with virtually no buffers.

This closed-feedback loop process is actually a formalization of the way controllers provide separation without

buffers in current operations. It is however worth highlighting that there is no conceptual incompatibility

between the use of closed-feedback loop processes and introduction of increased automation into ATM

separation provision processes. Using such processes to eliminate the need for buffers could significantly

improve the performance of TBO.

Decision support tools may help controllers in assessing the need for separation driven trajectory constraints

or rather using the closed-feedback loop process. Note that both in current operations and in the future TBO

concept, separation provision consists of a mixture of trajectory constraints and a closed-feedback loop

process. A clearance to proceed is not guaranteeing a conflict free path, but rather a guarantee that potential

conflicts are actively being controlled, either by the provision of a trajectory constraint (“safe clearance”) or by

the separation monitoring closed-feedback loop process described above.

Beyond the conflict horizon, rather than actively attempt to ensure separation greater or equal to the

separation minima, measures are taken to ensure the level of traffic complexity does not exceed predefined

criteria. A variety of measures is taken to limit complexity in current operations. Among them it is worth

highlighting Profile Tuning Restrictions (PTRs), which restrict AUs freedom to file their preferred 4D profile by

imposing pre-defined vertical restrictions along their route. In TBO, pre-defined PTRs are expected to be

replaced by ad-hoc measures that impact multiple trajectories and may require multi-actor coordination in a

collaborative decision making process.


TBO-CD R3.4.001 TBO shall distinguish between trajectory constraints for the purpose of separation

provision and trajectory constraints for other purposes;

TBO-CD R3.4.002 TBO shall define how trajectory constraints shall be used for the purpose of

separation provision;


3.5 TRAJECTORY CONSTRAINTS AND TOLERANCES

A distinction between the coordinated trajectory prediction (based on a common trajectory prediction) and a

trajectory constraint is required.

Figure 6 – Trajectory constraints

The use of trajectory constraints shall be minimised to the extent possible and to the tolerance level

commensurate with the ATM function it serves, to avoid limiting airborne operations more than is strictly

required.

One could for example adhere to a target time within a defined tolerance level of ± 2 minutes for arrival at a

metering fix, and simultaneously allow for fluctuations (within limits) in speed to keep the flight optimized in a

varying atmosphere, or add lateral or vertical trajectory constraints triggered by the need for conflict

resolution.


TBO-CD R3.5.001 The use of trajectory constraints shall be minimised to the extent possible and to

the tolerance level commensurate with the ATM function it serves, to avoid

limiting airborne operations more than is strictly required.

TBO-CD R3.5.002 TBO shall describe under what circumstances trajectory constraints should be

applied to avoid separation loss due to residual unpredictability;

Constraint 2(for separation or planning purposes)

Constraint 1(for separation or planning purposes)

downlinked trajectory prediction

Alternative trajectories that would have complied with constraints


4 CHARACTERISTICS OF TBO

4.1 TRAJECTORY MANAGEMENT LOOP

The management of trajectories in a changing ATM environment is a control loop consisting of monitoring the

various ATM functions (see section 2.1) against their objectives, detecting any “issues” stemming from any of

the GATMOC ATM components in any of the regions that require action, generating solutions either through

changing a local or regional ATM configuration (“major issue” impacting many trajectories; e.g. re-

sectorization or different runway combination) or through adding or changing trajectory constraints (“minor

issue” impacting one or several individual trajectories). Note that changing a local or regional ATM

configuration may impact other ATM components in the same or in other regions further upstream or

downstream of the trajectory.

Changing a trajectory constraint in itself is also a loop of proposing a (change to) a trajectory constraint,

predicting the trajectory based on the proposed trajectory constraint, evaluating the impact on the ATM

function(s) and finally agreeing on the trajectory constraint and its tolerance.

Once a trajectory constraint and its tolerance is agreed, it needs to be synchronized with involved actors, and

the trajectory prediction needs to be updated, taking into account this new trajectory constraint. Note that the

trajectory prediction also requires insight to the aircraft performance characteristics that constrain the

solution space.

Figure 7 – The trajectory management loop

Monitor ATM function(issue assessment)

Minorissue

Propose (change to) trajectory constraint(s)

Evaluate solution(impact on all GATMOC ATM components downstream)

Predict trajectory(shaped by proposed constraint)

Evaluate “what if” scenario (s)

Other trajectory predictions with their trajectory constraints

Constraints like aerodrome and

airspace structures,

Trajectory constraints

Change (future) ATM configuration

(future) ATM configuration

Majorissue

Manage ATM configuration

Change trajectory constraint(s)

Agree constraint(s)

Managetrajectory

TrajectoryPrediction

(including FMS)

ATMconfiguration

prediction

Synchronize agreed constraint(s)

between all actors(including A/G)

CDM

meteorological conditions, local rules

like night curfews

e.g. sector configurations, runway combinations, runway

usage, military airspace reservations and

releases


Trajectory negotiation requires a pre-established seamless negotiation process that allows rapid convergence

of solutions though support of automation (“fine-tuning” the trajectory). To accomplish this, the data to be

exchanged and the rules for decision-making must be defined and globally harmonized. Details of the

negotiation are established through a Collaborative Decision Making (CDM) process. Human-to-human

negotiation on an individual flight basis may occur by exception when necessary and when time permits.

In particular for the coordination phase, a distinction may be required in the type of trajectory constraints, e.g.

target trajectory constraint (should), controlled trajectory constraint (shall) and requested trajectory

constraint (proposal).

The TBO concept needs to clarify how roles and responsibilities will be changed to ensure adherence to the

agreed trajectory constraints. For example, time trajectory constraints may be implemented through active

management by ATC through speed instructions, but could also be managed by the flight crew through an FMS

RTA.


Doc 9882 R09 The ATM system shall use relevant data to dynamically optimize 4-D trajectory planning and operation;

Doc 9882

R183 The ATM system shall monitor and alert when indications are that an aircraft will not be in conformance/compliance with the agreement; Explanatory Text: Flight intent forms the basis for an ATM system agreement, and changes to the flight intent represent a request for modifications to the agreement. Aircraft intent forms the basis for ATM system confirmation of compliance with the agreement. The allowable variation from the agreed threshold is locally adaptable. Generating an agreement does not imply authority to execute. Initiating the agreement or any portion thereof requires a clearance. Clearances may not represent the entire agreement; the system shall alert the appropriate party when this is the case. The intent is to preclude an inadvertent entry into holding or inability to make the next trajectory point due to unintentional failure to provide follow-on clearance. The greater flexibility inherent in management by trajectory requires automated monitoring of adherence to and variance from the agreed trajectory. All ATM data will be available for accessing and use. The ATM system will automatically monitor, alert, and develop responses.

Doc 9882

R73 The ATM system shall monitor and alert when the clearance is inconsistent with the agreement;

Doc 9882

R68 The ATM system shall provide services predicated on management by trajectory and monitor compliance with the agreed trajectory;

Doc 9882

R212 The ATM system shall consider the trajectory of a vehicle during all phases of flight and manage the interaction of that trajectory with other trajectories or hazards to achieve the optimum system outcome with minimal deviation from the user-requested flight trajectory, whenever possible;

Doc 9882 (TS)

R82 The ATM system shall manage 4-D trajectory contracts to achieve safe and efficient trajectories; Explanatory Text Agreed 4-D trajectory contracts will be dynamically updated and communicated to the ATM community. Safety and efficiency in collaboration are key to the changes regardless of whether the service is done from the air or the ground. Negotiation and control will make use of the best available automated tools for communication, analysis, and action. It is expected that through dynamic renegotiations of agreed 4-D trajectory contracts— and subject to the appropriate business case to ensure cost-effectiveness—the ATM system will not experience “chokepoints.” Potential ATM system chokepoints should be increasingly more predictable as 4-D trajectories become available together with automated tools for mitigation. The balancing of traffic density with variations in demand should be based, where appropriate, using the 4-D trajectory contracts received from demand and capacity management. It is expected that automation both in the air and on the ground will be used fully in order to create an efficient and safe flow of traffic for all phases of flight. The ATM system, through full use of available automation, will be able to analyze and accurately predict future situations in order to achieve the best performance. Requirements for the airspace user to adhere to the agreed trajectory, within agreed tolerances, will remove much of the uncertainty regarding the future positions of aircraft.

Doc 9882 (TS)

R80 The ATM system shall provide for an orderly flow of traffic from gate to gate by dynamically renegotiating the 4D trajectory contract;



TBO-CD R4.1.001 TBO shall define the data to be exchanged in support of decision-making related to for trajectory constraints;

TBO-CD R4.1.002 TBO shall define the rules for decision-making related to trajectory constraints;

TBO-CD R4.1.003 Collaborative Decision Making (CDM) shall be applied for coordinating trajectory constraints;

TBO-CD R4.1.004 Human-to-human negotiation on trajectory constraints may occur only by exception when necessary and when time permits.

TBO-CD R4.1.005 TBO shall distinguish the type of trajectory constraints, e.g. target trajectory constraint (should), controlled trajectory constraint (shall) and requested trajectory constraint (proposal).

TBO-CD R4.1.006 TBO shall clarify how roles and responsibilities will be changed to ensure adherence to the agreed trajectory constraints.

4.2 MULTI ACTOR FRAMEWORK

The different ATM functions allow for involvement of different operational actors, with a combination of

actors that vary with the time horizon. Operational actors include the flight crew, air traffic control, tactical

planning, flow management and the flight operations centre.

Figure 8 - The multi-actor framework

Within the conflict horizon, time for coordination amongst different stakeholders may be limited allowing for

interaction between flight-crews and air traffic control only. Outside the conflict horizon, there is more time

for assessing what-if scenario’s involving multiple actors.

A coordination process, based on clear decision criteria and supported by automation, is required to

orchestrate the interaction between all stakeholders, ensuring stability and convergence of the ATM network.

Refinement on rules of interaction between operational stakeholders, involved through the various ATM

functions is required. The TBO concept specifies stakeholder’s roles and responsibilities to manage

(“ownership”) or contribute to the coordination of trajectory changes.


Doc 9882 R165 The ATM system shall ensure that, in the design of the ATM system, the principles of access and equity are taken into account; See also R188j in section 2.1

Doc 9882 R204 Based on global standards and uniform principles, ensure the technical and operational interoperability of ATM systems and facilitate homogeneous and nondiscriminatory global and regional traffic flows;

Leve

l of

invo

lvem

ent


Air traffic control

Flight crewFlight operations centre

Flow management Tactical planning

Global actors

Regional actors


Doc 9882 R205 Establish common operational procedures within similar operational environments;

Doc 9882 R12 Establish information exchange protocols and procedures to ensure that appropriate performance can be achieved within the agreed rules;

Doc 9882 R10 Ensure that the airspace user community is able to participate in collaborative decision making;


TBO-CD R4.2.001 Within the conflict horizon, assessment of what-if scenario’s may be limited to flight-crews and air traffic control only;

TBO-CD R4.2.002 Outside the conflict horizon, assessment of what-if scenarios shall involve all actors that may be impacted, including FOC, downstream ATC and flow management;

TBO-CD R4.2.003 TBO shall orchestrate the interaction between all stakeholders when making changes to trajectory constraints ensuring stability and convergence of the ATM network;

TBO-CD R4.2.004 TBO shall specify stakeholder’s roles and responsibilities to manage (“ownership”) or contribute to the coordination of trajectory changes;

4.3 FEDERATED ARCHITECTURE

The ATM functions are distributed over many different ANSPs that act as one ATM system that is built through

a federated architecture. The architecture in support of TBO seamlessly aligns with this federated architecture

which also eases the integration of Airports, FOC and FMS into the federated ATM system.

Once the trajectory management loop is refined, its functions can be mapped onto the federated architecture

and translated into globally harmonized rules, procedures and interactions between the various actors and

systems to coordinate on trajectory predictions and their generic and trajectory constraints.

Even a federated architecture requires trust amongst the contributing parties. The performance of trajectory

predictions need to be trustworthy and harmonized to be adequately accurate and reliable for the ATM

component they serve. This has to be independent of the stakeholder that provides them. The trajectory

constraints imposed to a trajectory must be trustworthy as being based on and compliant with globally agreed

principles and traceable to commonly known environmental limitations. All actors applying changes to a

trajectory must be trustworthy in supporting compliance with the trajectory constraints, and the aircraft’s

navigational capabilities must be trustworthy to be able to adhere to these trajectory constraints to the

tolerance level required.

Regarding navigational capabilities and trajectory prediction, a performance based approach is the way to

establish this required trust.


TBO-CD R4.3.001 The TBO architecture shall be closely aligned to the federated architecture of the GATMOC’s ATM components;

TBO-CD R4.3.002 TBO shall define globally harmonized rules implementing the trajectory management loop.

TBO-CD R4.3.003 TBO shall define globally harmonized ways to coordinate on trajectory predictions and their trajectory constraints.

TBO-CD R4.3.004 TBO shall map procedures and interactions onto the existing GATMOC ATM components: AOM, DCB, AO, TS, CM and AUO.

TBO-CD R4.3.005 Shared trajectory predictions shall be trustworthy to be sufficiently accurate and reliable for the purpose they serve;


TBO-CD R4.3.006 Trajectory constraints shall be traceable to commonly known environmental limitations, i.e. to generic constraints;

TBO-CD R4.3.007 All actors applying changes to a trajectory shall support compliancy with the trajectory constraints;

TBO-CD R4.3.008 Aircraft flying through TBO airspace shall be able to adhere to trajectory constraints to the tolerance level required;

4.4 INTEGRATING THE AIRCRAFT’S FMS

A key role is for the downlinked FMS trajectory prediction during flight-execution (and the FOC trajectory

prediction in the pre-departure phase) indicating the level of compliance to all coordinated generic and

trajectory constraints, as this closes the trajectory management loop. It provides verification on the feasibility

and synchronization of generic and trajectory constraints (and the resulting trajectory prediction) between

ground and airborne systems.

Avionics impact – up-linking trajectory constraints

To ensure consistency between air and ground trajectory predictions, the generic and trajectory constraints

that shape a trajectory need to be uplinked to the FMS. This can be done through A/G SWIM16

and CPDLC,

depending on the type of information. It is only when the generic and trajectory constraints on a trajectory are

all known to the FMS, that an FMS is capable of predicting a trajectory correctly. Note that uplinked trajectory

constraints will be considered as clearances that the flight must comply with (e.g. cross a certain point at a

certain time or a certain altitude/flight level).

Avionics impact – downlinking the FMS trajectory prediction

A downlinked trajectory prediction from the FMS enables a closed trajectory management loop, by confirming

that the aircraft’s FMS is consistent with any issued lateral or vertical trajectory constraints and/or target time,

provided they have been activated (armed) by the flight crew, and therefore included in the FMS’ trajectory

computation. Contrary to an internal ATC trajectory prediction, the FMS trajectory prediction extends beyond

ANSP boundaries, allowing using this trajectory prediction for other purposes in downstream centres, e.g. for

complexity management, DCB and arrival management.

Such a downlinked trajectory prediction shall not be interpreted as a contract but rather as intent. It reflects

the future trajectory predicted by the FMS, taking into account any coordinated generic and trajectory

constraints. The trajectory actually flown may differ from the intended flight trajectory, due to the intrinsic

flight operations uncertainties. Note however that uplinked trajectory constraints must be complied with (e.g.

cross a certain point at a certain time or a certain altitude/flight level). The use of trajectory constraints will be

limited to the specific needs of an ATM function, leaving as much flexibility as possible for pilots to optimize

their flight.

The downlinked trajectory prediction does not represent the ideal trajectory, but rather the trajectory

optimized by the airspace user, given any generic and trajectory constraints stemming from ATC, DCB and MET

that are known to the FMS.

In the lateral (2D) dimension, adherence of the aircraft’s current position is bound by the RNP

specification the aircraft flies to.

16

Initial A/G SWIM will not be certified for safety critical applications and provides information exchange to

the electronic flight bag (EFB). R&D in support of safety critical A/G SWIM that could connect directly to te

FMS is ongoing.


Adherence in the time dimension is not guaranteed to any specific accuracy unless the aircraft is flying

to a time trajectory constraint, which specifies tolerance at the waypoint to which the constraint is

allocated. On the trajectory up to that constraint the uncertainty may be different.

In a level segment of the downlinked trajectory prediction, the standard vertical adherence values

apply. For a downlinked trajectory prediction segment where an aircraft is either climbing or

descending, potential deviations from the vertical profile are not bound by any specific value unless

the aircraft if flying to an altitude trajectory constraint. In other words, the actual altitude deviation

from the predicted trajectory up to the constraint position and after the constraint position is

“uncertain”.


Doc 9882 R209 The ATM system shall make the best use of aircraft capabilities;

Doc 9882 R177 The ATM system shall ensure that aircraft capabilities will be totally integrated in the collaborative decision making process of the ATM community and allow them to comply with all relevant ATM system requirements;


TBO-CD R4.4.001 Trajectory constraints and trajectory prediction shall be synchronized between airborne and ground actors and systems (to the level required to perform its functions);

TBO-CD R4.4.002 Lateral, vertical constraints and/or time trajectory constraints shall be entered into the FMS and activated (armed) by the flight crew;

4.5 PERFORMANCE BASED NAVIGATION

ICAO performance-based navigation (PBN) specifies that aircraft RNP and RNAV systems performance

requirements be defined in terms of accuracy, integrity, availability, continuity and functionality required for

the proposed operations in the context of a particular airspace, when supported by the appropriate navigation

infrastructure. The TBO concept is not linked to a particular RNAV or RNP specification, but rather supports

operations with any navigation specification, and provides the framework to deal with its associated

uncertainty. Naturally, the more stringent the navigation specification, the less uncertainty over the 2D

trajectory needs to be accounted for.

Work is ongoing to improve RNP to support more deterministic Fixed Radius Transition (FRT) and scalable fixed

RNP values defined per segment leg; both in en-route (e.g. A-RNP 1), and in TMA through a deterministic

Radius-to-Fix turn (RF) (e.g. RNP0.3). Though not a pre-requisite for TBO, once being covered by RNP, TBO

requires that a trajectory can be defined in such terms in order to be able to coordinate on it.


Doc 9882 R209 The ATM system shall make the best use of aircraft capabilities;


TBO-CD R4.5.001 Regarding navigational accuracy, TBO shall build on current and future PBN definitions;

4.6 PERFORMANCE BASED TRAJECTORY PREDICTION

A 'predicted trajectory' represents the path that an aircraft is expected to follow from its current position

onwards as derived from a set of input data and assumptions. A great variety of input parameters need to be


taken into account when defining, changing or predicting a trajectory. These parameters are inherent to the

way the ATM functions are organized and stem from the domains of airspace user objectives, aircraft

performance characteristics, separation constraints, ATC network capacity, aeronautical structures and

meteorological forecasts and actuals.

The ATM functions differ significantly in the nature of the trajectory information they need, in particular their

time horizon. DCB typically need the flight profile for the whole flight. In current operations, tactical functions

need the trajectory prediction only with regard to the current sector, looking ahead less than 20 minutes. The

dynamics of the overall system reduces the reliability and accuracy of predictions over time and brings about

greater deviations. TBO seeks to reduce such deviations optimally, while also ensuring that look-ahead tools

operate within such limits.

In the current situation, different parts of the ATM network have different characteristics regarding their

trajectory predictions:

The FOC (Flight Operations Centre) computes an optimal trajectory calculated with full range of

inputs: full Meteorological model, detailed Aircraft Type and specification, Airline business rules,

Weight, however it is missing some information on the operational constraints that ATC may apply to

facilitate the 4D trajectory execution17

. The goal of this trajectory is to optimize all economic criteria

to define the optimum route associated to a cost index.

The aircraft FMS computes an optimal trajectory with limited range of inputs: a simplified

meteorological model (FOC datalink updates are possible); detailed aircraft Type; actual Weight; cost

index; similarly to the FOC, the FMS has little information on downstream constraints, usually entered

later as clearances are issued.

The ASP (either ATC or Flow Management facility) computes a trajectory on their domain of interest,

with precise knowledge of the local conditions, but using sometimes different constraint set depending

on the purpose of the calculation. Purposes include flow management, complexity management, STCA

and MTCD.18

Managing trajectories through the different ATM functions is conducted by coordinating and agreeing on input

parameters associated with that trajectory, resulting in a change of the intended trajectory, and, once agreed,

eventually a change to the actual trajectory. All ATM functions require a trajectory predictor to assess the

impact of changing input parameters – the “what-if” scenario - but their requirements on accuracy and horizon

vary.

The elements from the flow management, aeronautical and meteorological domains, are characterized by

geospatial and temporal aspects. These aspects can change over time, and therefore an event driven update

mechanism is required to trigger actors and systems about updates when surpassing a predefined threshold

level, based on accuracy requirements for a specific ATM function. The need for accurate and up-to-date input

parameters depends on the accuracy requirements of an ATM function. ATM functions requiring high

accuracy, e.g. separation assurance, will need all input parameters and a low threshold level for updates,

17

This is partly corrected with FF-ICE/1

18 Different processes may have different trajectory predictions. A trajectory prediction could be based on one

common trajectory synchronized between all users, by a coarse grain reference trajectory that is shared and used

by all users to build its own trajectory adding more specific knowledge or tuning it to more specific

requirements, or by synchronizing input parameters only and using performance based trajectory predictions.

Optimizing the solution is subject of ongoing research.


whereas other ATM functions, e.g. complexity management, have less stringent accuracy requirements and

therefore a less stringent threshold level for updates on trajectory prediction input parameters.


TBO-CD R4.6.001 For each ATM function the requirements on the trajectory prediction shall be defined in terms of scope and accuracy;

TBO-CD R4.6.002 Requirements on the trajectory prediction in terms of scope and accuracy shall be translated into required input parameters for trajectory prediction; Input parameters include trajectory constraints, but also AIM or MET generic constraints;

TBO-CD R4.6.003 What-if scenario’s shall be coordinated through proposed changes on trajectory constraints

TBO-CD R4.6.004 An event driven update mechanism shall be implemented to trigger actors and systems about updates of trajectory prediction input parameters when surpassing a predefined threshold level; The threshold level shall be based on accuracy requirements for a specific ATM function


5 THE SOLUTION SPACE

This chapter is not intended to be mature for the ATMRPP in March 2015. It only provides an indication of

what is expected here, by providing some examples that build the solution space. Further work has to be done

in future updates of this document.

5.1 SYNCHRONIZING THE TRAJECTORY PREDICTION

Status: FF-ICE

By continuously sharing, updating and coordinating changes to an air-ground synchronised view of the

expected remainder of the trajectory for a flight between all ATM stakeholders, all gain awareness to better

anticipate and respond on events that are about to happen. FF-ICE/1 prepares for this, limited to the pre-

departure trajectory prediction only.

5.2 INCLUDE SURFACE MOVEMENTS IN TRAJECTORY PREDICTION

Status: Proposal

Enabling stakeholders on the airport to share data, collaborate and establish a cohesive strategic plan for

movement of aircraft on the surface leads to improved efficiency of ground operations which directly affects

arrival and departure flows.

5.3 CLOSED LOOP VECTORING

Status: Proposal

In current operations, separation provision makes extensive use of vectoring. The air traffic controller who has

issued a heading clearance will usually have a reasonably accurate plan in mind as to how he will clear the

flight to resume own navigation, i.e. re-join the initially intended flight path. The elastic vector is the

operational concept for describing the action of a controller entering this plan into the ATC systems. The

elastic vector enables that the controllers plan is visible to all actors. Even when the elastic vector is used,

controllers still need to close the loop by actually issuing the clearance for the aircraft to actually resume own

navigation.

The TBO concept is based on all actors having a common view of the trajectory. In this case, this would require

the elastic vector to be uplinked to the aircraft, so that air and ground both share the knowledge of how the

controller intends to close the open-loop vector. The controller’s elastic vector plan may involve certain pre-

requisites (e.g. another aircraft to leave a certain flight level or finish a turn) which may make it unsafe to

actually deliver the clearance to proceed according to the elastic vector, before the pre-requisites have

actually happened. As a consequence, in TBO the elastic vector uplink may or may not be combined with the

simultaneous uplink of a clearance to proceed according to the elastic vector.


5.4 TIME CONSTRAINTS

Status: Proposal

For the majority of the GATMOC’s ATM components (i.e. for AOM, DCB, AO and TS), the only relevant element

of predictability is milestone planning with tolerance levels tailored to a specific function. Higher granular

details of the coordinated trajectory intention are not required for these functions.

In order to avoid over-constraining and reducing flexibility, the timing for setting a time-constraint as well as

the time constraints tolerance level need to be tailored commensurate with the ATM function they serve as

well as with the expected traffic demand. This is illustrated in figure 9. Also, a distinction may be required in

the type of time constraints, e.g. target times (should), controlled times (shall) and requested times (proposal).

Figure 9: The optimum between flexibility and predictability when using time constraints

Tolerance levels and timing for AOM, DCB, AO, TS (E-AMAN, DMAN, SMAN, crossing points) and SEP time

targets are not the same. Time constraints can be specified by a specific time with specific tolerance level, a

“before” time or an “after” time. Time constraints may apply to a departure time, to a time over a way point,

or to an arrival time. An aircraft can only fly to one time-constraint at a time and therefore will manage

multiple time-constraints sequentially, i.e. one at a time.

5.4.1 TIME CONSTRAINTS IN SUPPORT OF SEPARATION PROVISION

Status: SESAR concept under validation

Adherence to time constraints can be used for separation provision. In this case, adherence tolerances result

in uncertainty over the aircraft position, which will need to be accounted for in the separation minima to be

used. For this reason, high accuracy in meeting time constraints will need to be required in order to make

better use of airspace capacity.

Time

Flig

ht

dis

tan

ce

Destination

Origin

Optimise moment to fine tune target time at Fix: Not too early, not too late

Congested sector

Congested runway

Optimize interval ensuring fluctuations to average out

Plannedtrajectory

Compliant trajectories

Though the final RTA window does not match the originally planned trajectory, it does serve

its purpose for arrival management

Initial RTA tolerance

Final fine-tunedRTA tolerance


Figure 10: Additional separation to compensate for inaccuracy in time adherence

Note: The need for separation buffers may be avoided by using closed-feedback loop processes to control the

execution of separation provision tasks. At each process loop, the crossing point become closer, and therefore

uncertainty over the future trajectory is reduced, and assessment of whether separation will actually be safe

becomes more reliable. At each process loop, further action can be taken to ensure safe separation if deemed

necessary. Close to the conflict point, uncertainty becomes negligible, and therefore in the last process loop-

cycles separation can be guaranteed tactically with virtually no buffers. This closed-feedback loop process is

actually a formalization of the way controllers provide separation without buffers in current operations. It is

however worth highlighting that there is no conceptual incompatibility between the use of closed-feedback

loop processes and introduction of increased automation into ATM separation provision processes. Using such

processes to eliminate the need for buffers could significantly improve the performance of TBO.

5.4.2 TIME CONSTRAINTS IN SUPPORT OF ARRIVAL MANAGEMENT

Status: Validated SESAR concept, ready for deployment

E-AMAN processes ultimately aim at producing a landing sequence where aircraft are as close as it is safe for

them to be, and may thus benefit from smaller tolerance intervals than DCB processes, which only need to

ensure that traffic density in a specific area remains manageable for controllers.

Note: E-AMAN systems need to ensure a certain amount of over-delivery to the arrival metering fix in

order to avoid gaps in the approach sequence, which would result in runway under-utilization. Over-

delivery may cause aircraft that reach the metering fix at their E-AMAN -planned time to still need to

absorb some additional delay. The need for over-delivery is a consequence of uncertainty, and it is

therefore reasonable to expect that it can be reduced by reducing uncertainty.

5.4.3 TIME CONSTRAINTS IN SUPPORT OF DCB

Status: Pre-departure time adherence operational in Europe’s CFMU, US Ground Delay Program and in

Australia. Airborne time adherence under validation in SESAR.

When demand over a particular fix or sector exceeds capacity during the planning phase, time constraints may

be allocated to a point on the trajectory, to spread demand by delaying individual flights.

Note: If multiple time constraints are allocated, the TBO concept needs to define how to deal with

conflicts in this. A possibility would be to choose the biggest required delay (by Europe’s Network

Separation Separation Separation


Manager applied as the Most Penalising Regulation) and apply that delay to the entire trajectory.

Airspace Users could be allowed a certain degree of airline network optimization by swapping time slots

between different flights within their network that fly within the same constraining sector. Note that the

FMS cannot handle multiple time constraints simultaneously. The feasibility of multiple time constraints

is subject of further research.

5.5 ALTITUDE CONSTRAINTS

Status: Common practice worldwide

Altitude targets (above, below, between; tolerance)

o Level capping

o Altitude constraints

o Early descend

TBD: it may be relevant to add all the other elements of “the container constraints” such as:

o Met

o Airspace (e.g.: military activities, limitations to use FR/Directs,..)

o …

5.6 IMPROVED CLIMB AND DESCEND PROFILES

Status: SESAR concept under development

5.7 PRE-DEPARTURE RANKED TRAJECTORIES

Status: Implemented by FAA

When airspace constraints are expected, during flight preparation prior to departure, the FOC may submit one

or possibly several prioritized desired trajectories to the ANSP. These trajectories and associated data are

known as a Trajectory Option Set (TOS) or “ranked trajectories”. The Airspace User submits their TOS to the

ANSP. The ANSP receives the TOS from the FOC/Airspace User via automation and determines which highest

priority trajectory is feasible based on the ATM constraints as defined by the CDM process.

5.8 SLOT-SWAPPING (UDPP)

Status: SESAR concept ready for deployment

From an Airspace Users’ point of view, not all flights are equal in terms of schedule priority. If two flights from

the same airline crossing the same congested airspace or airport are both given time constraints, the Airspace

User may swap these time constraints to reorder their flights aligned to the airline’s priorities.


6 AGREEING TRAJECTORY CHANGES

This chapter is not intended to be mature for the ATMRPP in March 2015. It only provides an indication of

what is expected here, by providing some examples that describe how trajectory changes could be agreed.

Further work has to be done in future updates of this document.

6.1 INTERDEPENDENCIES BETWEEN HOT SPOTS

Need to explain how to interact/interrelate constraints and tolerances between the ATM functions acting on

the trajectory;

Status: No information on this available, except for how this works in Europe (Most Penalizing Regulation).

6.2 PREFERRED SOLUTIONS FOR CONFLICT MANAGEMENT ENROUTE

Status: Proposed

For most purposes the only relevant element of predictability is milestone planning with tolerance levels

tailored to a specific ATM function. If a time constraint exists further downstream, then a preference should be

given to the solutions that optimizes the trajectory up to this bottleneck, in general this would be the solution

that has minimal impact on the milestone planning of the trajectory further downstream.

For example enroute lateral vectoring 100 NM in advance causes only a few seconds delay, whereas solving the

same conflict through setting a time target may cause a delay or speeding up of 1 minute. Another example

comes from the early release of military airspace that would provide an unpredicted opportunity for a short cut.

With a time constraint further downstream, the short cut may not be optimal for the trajectory.

6.3 PREFERED SOLUTIONS FOR DELAY ABSORBTION IN ARRIVAL PHASE

Status: Proposed

Absorbing delay in the arrival phase is completely different. Since the total flight time to be flown by each

flight is an independent variable determined by its landing slot, total fuel-burn can only be minimised by flying

the aircraft slowly while still in clean configuration. Time constraints that slow down an aircraft in clean

configuration and early descent followed by flight at maximum endurance speed are both going to contribute

to smaller fuel consumption numbers. When all delay cannot be absorbed by those two methods, path

stretching or holding will need to be used. In such cases, there is a relatively small difference19

between

absorbing delay at high altitude compared to doing so at lower altitude.

19

A more accurate comparison depends on aerodynamics, engine performance and is even aircraft type specific


7 GLOBALLY HARMONIZED INFORMATION EXCHANGES

This chapter is not intended to be mature for the ATMRPP in March 2015. It serves as a place holder for a

description of information exchanges that require global harmonization. The information exchanges include

cross FIR coordination, as well as AU involvement.

8 TRANSITION AND TECHNICAL ENABLERS (I-TBO)

This chapter is not intended to be mature for the ATMRPP in March 2015. It serves as a place holder for a

description of technical enablers in support of TBO that are available or still under development but expected

to become available for early deployment. The intent is to fit the pieces of the puzzle, being already developed

in the various research programs, resulting in a description of how this could work together in a first step

towards full TBO. Further work has to be done in future updates of this document.

8.1 ROADMAP OF TECHNICAL ENABLERS

TBD

ADS-B

ADS-C EPP

CPLDC

PBN

FMS RTA capabilities

FF-ICE/1

FIXM

8.2 MIXTURE OF TBO AND NON-TBO AIRCRAFT

TBD

8.3 MIXTURE OF TBO AND NON-TBO ANSPS

TBD


9 OPEN ISSUES

This chapter is a temporary placeholder for any issues that are being encountered during the development of

the TBO concept. Issues may be conceptual and/or linked to operational validation. Once addressed in the TBO

concept, the issues will be removed from this chapter. In the final version of the document this chapter shall

be removed.

Relationship to best equipped, best served; does TBO impose requirements on BEBS?

TBD: clarify link to FIXM, ED-133, etc

TBD: Clarify differences between types of time constraints, e.g. TTA/TTO, CTA/CTO, RTA


10 REFERENCES

1. ICAO Doc 9854, AN/458, Global Air Traffic Management Operational Concept

2. ICAO Doc 9882, AN/467, ATM System Requirements Supporting the Global Air Traffic Management

Operational Concept

3. ICAO Doc 4444, ATM/501, Procedures for Air Navigation Services

4. ICAO Circular 335, AN/194, ATM Service Delivery Management (ATM SDM)

5. ICAO/ATMRPP WG/25 WP/601 Managing unpredictable evolution in trajectory based operations

Henk Hof, Olivia Nunez, Richard Pugh, Ruben Flohr (SESAR), 3 March 2014

6. ICAO/ATMRPP WG/25 WP/603 Proposal for the development of TBO Concept

John Moore, 3 March 2014

7. ICAO/ATMRPP WG/26 WP/620 TBO Proposed Definition, Story, Key Terms and ToC

John Moore / Jorge Woods (Australia), 7 July 2014

8. ICAO/ATMRPP WG/26 WP/632 SESAR comments on TBO

Henk Hof, Philippe Trouslard, Olivia Nunez, Philippe Leplae, Ruben Flohr (SESAR), 27 June 2014

9. ICAO/ATMRPP WG/27 WP/634 Trajectory Based Operations Concept Document, draft JW0d24

John Moore / Jorge Woods (Australia), 27 October 2014

10. ICAO/ATMRPP WG/27 WP/636 Time adherence in TBO

Henk Hof / Ruben Flohr / Olivia Nunez / Robin Garrity (SESAR), 14 October 2014

11. ICAO/ATMRPP WG/27 WP/637 Sharing Trajectory Predictions in TBO

Henk Hof / Philippe Leplae (SESAR), 17 October 2014

12. ICAO/ATMRPP WG/27 WP/641 Dynamically optimized path with TBO

Didier Delibes / Didier Delibes / Aslaug Haraldsdottir (ICCAIA), 20 October 2014

13. ICAO/ATMRPP WG/27 WP/644 US Trajectory Based Operations (TBO) Concept of Operations

Richard Jehlen (FAA), 20 October 2014

14. ICAO/ATMRPP WG/27 WP/649 Input to the ATMRPP Trajectory Based Operations (TBO) CONOPS

Richard Jehlen (FAA), 20 October 2014

15. FAA 4D Trajectory Based Operations (4D TBO) Concept of Operations (CONOPS)

Version 0.8 October 9, 2014

16. SESAR definition phase, The ATM target concept

DLM-0612-001-02-00a – September 2007


17. SESAR development phase, Concept of Operations Step 1, edition 01.02.00

B.04.02 D66, 02/04/2014

18. SESAR development phase, Concept Of Operations Step 2, version 01.00.00

B.04.02 D65-013, 03/09/2013


APPENDIX A – TBO SPECIFIC REQUIREMENTS

This appendix provides a full list of all requirements on the TBO concept that have been captured throughout

the document. The requirements numbering reflects the section numbers from which the requirements

originate. For example R2.1.001 is the first requirements from section 2.1.

Requirements that drive the definition of the TBO concept itself are marked yellow and shall be removed once

the TBO is finalized.

The problem space

TBO-CD R2.1.001 Trajectory predictions shall be adequately synchronized between stakeholders

TBO-CD R2.1.002 Trajectory and/or generic constraints that shape a trajectory, originating from various GATMOC ATM components (AOM, DCB, AO, TS, CM, AUO) and the various regions, shall be consistent.

TBO-CD R2.1.003 The trajectory definition shall be able to support a free-route environment;

Synchronizing information across stakeholders

TBO-CD R2.2.001 The quality of service of the synchronization of the expected remainder of the trajectory between stakeholders shall be commensurate with the required accuracy and reliability of the various ATM components to monitor compliance to the trajectory constraints - originating from such an ATM component - and their tolerance levels.

Ensuring consistency between trajectory constraints

TBO-CD R2.3.001 The combination of the solutions proposed by various ATM components that run in parallel (AOM, DCB, AO, TS, CM and AUO) shall be stable and consistent;

TBO-CD R2.3.002 An efficiently converging coordination process shall be applied to find a stable and consistent combination of solutions proposed by the various ATM components;

TBO-CD R2.3.003 Unambiguous criteria shall be applied for the prioritization of AOM, DCB, AO, TS, CM and AUO problems and an order of preference shall be applied in choosing between alternatives of their corresponding solutions;

RBO-CD R2.3.004 The TBO concept shall define how to manage trajectory constraints from the various ATM components, especially if the trajectory constraints are incompatible;

Integrating the airline perspective

TBO-CD R2.4.001 TBO shall define which airspace user operational information, flight parameters and aircraft performance characteristics need to be provided by the airspace user;

TBO-CD R2.4.002 TBO shall define how and to what extent to include airspace users, FOC and flight crew, into the process of trajectory changes, balancing flexibility for prioritization and optimizing airspace users operations while simultaneously ensuring sufficient predictability needed to optimize the ATM network as a whole;

TBO-CD R2.4.003 The flexibility needs from an individual Airspace User and the needs for predictability from the wider ATM network shall be balanced;

TBO-CD R2.4.004 TBO shall address pre-flight planning, surface, arrival and departures, and enroute operations;

TBO-CD R2.4.005 TBO shall describe the high level needs regarding “aeronautical information” which will allow the Airspace Users to better anticipate and respond and validate their operational choices depending on airspace characteristics.

Residual unpredictability

TBO-CD R2.5.001 TBO shall be resilient to changing circumstances and shall provide the means to


deal with residual unpredictability.

TBO-CD R2.5.002 The trajectory prediction and trajectory constraints shall be continuously refined and revised during the execution phase, based on latest data, observations and predictions, in order to continuously find the optimum balance between sometimes conflicting demands from different stakeholder perspectives: the flight itself; the airlines; the ATM network; and Air Traffic Services.

TBO-CD R2.5.003 TBO shall allow as much as possible, to change the trajectory in a way that is optimal for the airspace users

TBO-CD R2.5.004 TBO shall define to what accuracy level airspace users shall be capable to meet trajectory constraints;

TBO-CD R2.5.005 TBO shall define how to coordinate and agree changes on trajectory constraints; This includes both individual trajectory changes, as well as adjusting many trajectories simultaneously, triggered by a single event;

Evolution, not revolution

TBO-CD R2.6.001 TBO shall identify dependencies between technical enablers, in support of the development of a deployment roadmap;

TBO-CD R2.6.002 TBO shall be resilient against a mixed equipage aircraft environment;

TBO-CD R2.6.003 TBO shall be resilient against a mix of TBO compliant and non-TBO compliant ANSPs;

TBO-CD R2.6.004 TBO shall define aircraft capabilities in terms of types of trajectory constraints and required accuracy level that an aircraft shall be capable to adhere to;

TBO-CD R2.6.005 TBO shall clarify how the discrepancy between air and ground trajectory predictions will be handled

ATC clearances and instructions

TBO-CD R3.2.001 TBO shall clarify the difference between the coordinated trajectory prediction and

a clearance.

TBO-CD R3.2.002 TBO shall define the form and means of communication of ATC clearances and

instructions;

TBO-CD R3.2.003 TBO shall define which ATC can give a clearance at a given moment and for which

portion of the trajectory

Closed loop clearances

TBO-CD R3.3.001 Elastic vector concept: The controller’s intent to make an aircraft re-join the

initially intended flight path after a vector instruction shall be registered and

visible to all actors;

TBO-CD R3.3.002 It shall be possible to uplink with a single data link command the elastic vector and

the clearance to proceed according to the elastic vector;

Conflict horizon

TBO-CD R3.4.001 TBO shall distinguish between trajectory constraints for the purpose of separation

provision and trajectory constraints for other purposes;

TBO-CD R3.4.002 TBO shall define how trajectory constraints shall be used for the purpose of

separation provision;

Trajectory constraints and tolerances

TBO-CD R3.5.001 The use of trajectory constraints shall be minimised to the extent possible and to

the tolerance level commensurate with the ATM function it serves, to avoid


limiting airborne operations more than is strictly required.

TBO-CD R3.5.002 TBO shall describe under what circumstances trajectory constraints should be

applied to avoid separation loss due to residual unpredictability;

Trajectory management loop

TBO-CD R4.1.001 TBO shall define the data to be exchanged in support of decision-making related to for trajectory constraints;

TBO-CD R4.1.002 TBO shall define the rules for decision-making related to trajectory constraints;

TBO-CD R4.1.003 Collaborative Decision Making (CDM) shall be applied for coordinating trajectory constraints;

TBO-CD R4.1.004 Human-to-human negotiation on trajectory constraints may occur only by exception when necessary and when time permits.

TBO-CD R4.1.005 TBO shall distinguish the type of trajectory constraints, e.g. target trajectory constraint (should), controlled trajectory constraint (shall) and requested trajectory constraint (proposal).

TBO-CD R4.1.006 TBO shall clarify how roles and responsibilities will be changed to ensure adherence to the agreed trajectory constraints.

Multi actor framework

TBO-CD R4.2.001 Within the conflict horizon, assessment of what-if scenario’s may be limited to flight-crews and air traffic control only;

TBO-CD R4.2.002 Outside the conflict horizon, assessment of what-if scenarios shall involve all actors that may be impacted, including FOC, downstream ATC and flow management;

TBO-CD R4.2.003 TBO shall orchestrate the interaction between all stakeholders when making changes to trajectory constraints ensuring stability and convergence of the ATM network;

TBO-CD R4.2.004 TBO shall specify stakeholder’s roles and responsibilities to manage (“ownership”) or contribute to the coordination of trajectory changes;

Federated architecture

TBO-CD R4.3.001 The TBO architecture shall be closely aligned to the federated architecture of the GATMOC’s ATM components;

TBO-CD R4.3.002 TBO shall define globally harmonized rules implementing the trajectory management loop.

TBO-CD R4.3.003 TBO shall define globally harmonized ways to coordinate on trajectory predictions and their trajectory constraints.

TBO-CD R4.3.004 TBO shall map procedures and interactions onto the existing GATMOC ATM components: AOM, DCB, AO, TS, CM and AUO.

TBO-CD R4.3.005 Shared trajectory predictions shall be trustworthy to be sufficiently accurate and reliable for the purpose they serve;

TBO-CD R4.3.006 Trajectory constraints shall be traceable to commonly known environmental limitations, i.e. to generic constraints;

TBO-CD R4.3.007 All actors applying changes to a trajectory shall support compliancy with the trajectory constraints;

TBO-CD R4.3.008 Aircraft flying through TBO airspace shall be able to adhere to trajectory constraints to the tolerance level required;

Integrating the aircraft’s FMS

TBO-CD R4.4.001 Trajectory constraints and trajectory prediction shall be synchronized between airborne and ground actors and systems (to the level required to perform its functions);


TBO-CD R4.4.002 Lateral, vertical constraints and/or time trajectory constraints shall be entered into the FMS and activated (armed) by the flight crew;

Performance based navigation

TBO-CD R4.5.001 Regarding navigational accuracy, TBO shall build on current and future PBN definitions;

Performance based trajectory prediction

TBO-CD R4.6.001 For each ATM function the requirements on the trajectory prediction shall be defined in terms of scope and accuracy;

TBO-CD R4.6.002 Requirements on the trajectory prediction in terms of scope and accuracy shall be translated into required input parameters for trajectory prediction; Input parameters include trajectory constraints, but also AIM or MET generic constraints;

TBO-CD R4.6.003 What-if scenario’s shall be coordinated through proposed changes on trajectory constraints

TBO-CD R4.6.004 An event driven update mechanism shall be implemented to trigger actors and systems about updates of trajectory prediction input parameters when surpassing a predefined threshold level; The threshold level shall be based on accuracy requirements for a specific ATM function


APPENDIX B – ICAO DOC 9882 ATM SYSTEM REQUIREMENTS RELATED TO TBO

ICAO doc 9882 defines high-level requirements (hereafter referred to as ATM system requirements) supporting

the GATMOC to be used in conjunction with the GATMOC from which the requirements were derived. The ATM

system requirements shall be applied in developing Standards and Recommended Practices (SARP) to realize

the concept. The following requirements have been identified as being applicable to the TBO concept.

Topic ID The ATM system shall:

General R97a Ensure that performance forms the basis for all ATM system development;

R97b The ATM system shall ensure that performance targets are defined, regularly reviewed and monitored;

R85 Treat performance as a whole, that is, considering all the ATM community expectations and their relationships;

R188j The ATM system shall balance the expectations of the ATM community Explanatory Text: The ATM system will consider the trajectory of a vehicle during all phases of flight and manage the interaction of that trajectory with other trajectories or hazards to achieve the optimum system outcome with the minimal deviation from the user-requested flight trajectory, whenever possible. The ATM system will provide seamless service to the user at all times and will operate on the basis of uniformity throughout all airspace. Uniformity embodies both application of common ATM system rules and procedures across all airspace and use of common core, technical functionality in the systems used. It is not intended that this will establish an all-embracing requirement for identical equipment or systems, although minimizing system duplication or reducing equipment or systems needed to operate in a global ATM system environment is an obvious goal. It is intended that agreed required minimum levels of aircraft equipment, performance, and ATM system network capabilities will be matched by defined levels of service. It is intended that the ATM system should provide all users, at a minimum, the same level of access to runways and airspace when compared to a regionally agreed baseline year.

R158a Establish Quality of Service requirements to support provision of services within the ATM system;

R187 Ensure that all information for performance management is available to the concerned parties transparently and that information disclosure rules are in place;

R188 Balance the expectations of the ATM community;

Safety R162 The ATM systems shall be designed so that the operation and continued evolution of the ATM system incorporates mechanisms so that information and/or actions concerning emergency and/or unexpected events involving any of the airborne or ground-based ATM community members can be communicated to all ATM system participants who need to respond to or be aware of the event or actions;

Access and equity

R165 The ATM system shall ensure that, in the design of the ATM system, the principles of access and equity are taken into account; See also R188j in section 2.1

Capacity R199 The ATM system shall minimize the impact of adverse weather on the total ATM system, so as to ensure that maximum throughput is generated in all meteorological conditions;

Flexibility R181 The ATM system shall implement and operate in such a way that the varying and diverse user requirements will be met as closely as technically possible within the defined equity and access;

R201 Enable all airspace users to adjust departure and arrival times and modify flight trajectories dynamically, where necessary renegotiating trajectory agreements, thereby permitting them to exploit operational opportunities as they occur;

Efficiency R202 Address the operational and economic cost-effectiveness of gate-to-gate


flight operations from a single-flight perspective;

R203 Modify the airspace user’s preferred trajectory: iii. when required to achieve overall ATM system performance

requirements; and/or iv. collaboratively with the airspace user, in a manner that recognizes

the airspace user’s need for single-flight efficiencies

Global Interoperability

R204 Be based on global standards and uniform principles, ensure the technical and operational interoperability of ATM systems and facilitate homogeneous and nondiscriminatory global and regional traffic flows;

R205 Establish common operational procedures within similar operational environments;

Information Services

R70 Implement system wide information management

R12 Establish information exchange protocols and procedures to ensure that appropriate performance can be achieved within the agreed rules;

R07 Ensure that the airspace user makes available relevant, operational information to the ATM system;

R08 Use relevant, airspace user operational information to optimize flight operation management;

R09 Use relevant data to dynamically optimize 4-D trajectory planning and operation;

R31 Make available to the ATM system flight parameters and aircraft performance characteristics;

Collaboration R10 Ensure that the airspace user community is able to participate in collaborative decision making;

R11 Ensure mutual exchange of relevant and timely data: − for the benefit of situational awareness; − for conflict-free trajectory management; and − to allow collaborative decision making concerning consequences of airspace user system design changes;

Aircraft design R209 Make the best use of aircraft capabilities;

R177 Ensure that aircraft capabilities will be totally integrated in the collaborative decision making process of the ATM community and allow them to comply with all relevant ATM system requirements;

ATM component

ID The ATM system shall:

AOM R03 Allocate volumes that enable safe and efficient trajectory allocation and modification, from strategic to tactical;

AO R27 Ensure that flight parameters and aircraft performance characteristics are available to the ATM system; Explanatory Text As is the case across the whole ATM system, in relation to aerodrome operations, the availability and exchange of information will facilitate management by trajectory. It is expected that the collaborative exchange process and respective facilities will allow for efficient management of air traffic flow through use of information on a system wide basis of air traffic flow, weather, and assets. This process will also allow, for example, allocation of entry/exit times for aerodromes and subsequent dynamic changes to mitigate for any imbalance.

DCB R36d Utilize projected traffic demand and planned trajectories

R36e Accommodate revisions to trajectory requests and resources status

R36g Facilitate collaboration on trajectory changes and traffic demands

TS R80 Provide for an orderly flow of traffic from gate to gate by dynamically renegotiating the 4D trajectory contract;

R82 Manage 4-D trajectory contracts to achieve safe and efficient trajectories; Explanatory Text Agreed 4-D trajectory contracts will be dynamically updated and communicated to the ATM


community. Safety and efficiency in collaboration are key to the changes regardless of whether the service is done from the air or the ground. Negotiation and control will make use of the best available automated tools for communication, analysis, and action. It is expected that through dynamic renegotiations of agreed 4-D trajectory contracts— and subject to the appropriate business case to ensure cost-effectiveness—the ATM system will not experience “chokepoints.” Potential ATM system chokepoints should be increasingly more predictable as 4-D trajectories become available together with automated tools for mitigation. The balancing of traffic density with variations in demand should be based, where appropriate, using the 4-D trajectory contracts received from demand and capacity management. It is expected that automation both in the air and on the ground will be used fully in order to create an efficient and safe flow of traffic for all phases of flight. The ATM system, through full use of available automation, will be able to analyze and accurately predict future situations in order to achieve the best performance. Requirements for the airspace user to adhere to the agreed trajectory, within agreed tolerances, will remove much of the uncertainty regarding the future positions of aircraft.

R182 Use 4-D trajectory control and/or flight deck delegation for aircraft spacing;

R87 Utilize the 4-D trajectory for traffic synchronization applications to meet the ATM system performance targets, unless under certain conditions other means are determined to be more effective; Explanatory text It is expected that flight plans will be replaced by 4-D trajectory contracts for all phases of flight. 4-D trajectory contracts will constitute a prerequisite for dynamic control of aircraft and vehicles. Negotiations will take place dynamically, as total awareness will be available to the complete ATM community. Agreed 4-D trajectories will increase predictability as well as reduce the need for current traditional path-stretching methodologies. It is expected that spacing between aircraft will be done through the use of 4-D trajectories, which will be updated and interacted upon collaboratively. The 4-D trajectories will be provided as 4-D trajectory contracts and will be modified and acted upon dynamically and according to at least the criteria defined by conflict management to create a safe and orderly flow of traffic. It is expected that spacing between aircraft will be done through the use of 4-D trajectories, which will be updated and interacted upon collaboratively. The 4-D trajectories will be provided as 4-D trajectory contracts and will be modified and acted upon dynamically and according to at least the criteria defined by conflict management to create a safe and orderly flow of traffic.

Airspace User Operations

R44 Recognize and exploit airspace user capabilities to generate, negotiate, and adhere to user-preferred 4-D trajectories;

R212 Consider the trajectory of a vehicle during all phases of flight and manage the interaction of that trajectory with other trajectories or hazards to achieve the optimum system outcome with minimal deviation from the user-requested flight trajectory, whenever possible;

R43 Provide, consistently with available ATM system resources, airspace users the capability to fly dynamic user-preferred 4D trajectories; Explanatory Text: It is expected that user-preferred trajectories will provide the most efficient flight operations and that the airspace users will provide these trajectories to the ATM system. These trajectories should be the key/core element of the (shared) information management. The expectation is that the global exchange of information (from individual aircraft performance up to ATM resources) should allow full use of 4-D trajectory management/operation. The expectation is that the 4-D trajectory management optimization could be a function of either the ground or the air or both.

R116 Allow airspace users to fly user-preferred trajectories that are consistent with the applicable airspace management requirements and aircraft capabilities

Conflict Management

R81 Determine the separator (red – the actor that will provide separation) for each renegotiated 4-D trajectory;

ATM Service Delivery Management

R68 Provide services predicated on management by trajectory and monitor compliance with the agreed trajectory;

R71 Operate on the basis that the airspace user will provide flight and aircraft intent to the ATM system for use in planning and managing 4-D trajectories;

R72 Approve execution of 4-D trajectory agreements through issuance of clearances;

R73 Monitor and alert when the clearance is inconsistent with the agreement;

R183 Monitor and alert when indications are that an aircraft will not be in conformance/compliance with the agreement;


Explanatory Text: Flight intent forms the basis for an ATM system agreement, and changes to the flight intent represent a request for modifications to the agreement. Aircraft intent forms the basis for ATM system confirmation of compliance with the agreement. The allowable variation from the agreed threshold is locally adaptable. Generating an agreement does not imply authority to execute. Initiating the agreement or any portion thereof requires a clearance. Clearances may not represent the entire agreement; the system shall alert the appropriate party when this is the case. The intent is to preclude an inadvertent entry into holding or inability to make the next trajectory point due to unintentional failure to provide follow-on clearance. The greater flexibility inherent in management by trajectory requires automated monitoring of adherence to and variance from the agreed trajectory. All ATM data will be available for accessing and use. The ATM system will automatically monitor, alert, and develop responses.

R98 Utilize flight trajectory, flight intent, and individual aircraft performance characteristics in providing ATM services; Explanatory Text: It is expected that the 4-D trajectory will be globally shared and used by the ATM community in all aspects of its operations. The requirement recognizes the difference between the tolerances associated with the 4-D contracts and what may be more stringent performance capabilities of the individual aircraft. For example, aircraft providing the ATM system with knowledge of their very accurate performance capabilities would, as a result, provide the ATM system opportunity to identify conformance/compliance irregularities that could be used in providing such services as conflict management, security notification/response, and so on.

R153 Operate on the basis that where there is a conflict between access and equity, allocation of priority to airspace users will be based on the principle of maximizing ATM system performance; Explanatory Text: Existing practices relating to access and equity, particularly the “first come-first served” paradigm, should be amended to reflect the overall intent to improve ATM system performance. This is not intended to prohibit or block access to airspace; it is intended to allow establishment of procedures through collaborative decision making that optimize use of runways and/or airspace.

t o on ept - sesar joint undertaking...that run in parallel (aom, dcb, ao, ts, cm and auo), together...

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