ISSUE RESOLUTION Date :December 2012

Issue Title: Definition of Precision Trajectory Clearance (PTC)Abstract

This report will reflect a consensus reached amongst operational key players in the definition of “Precision Trajectory Clearance” (PTC).The report focuses on PTC in Step 2, where trajectory based operations come into full effect; a common understanding of the concept in Step 2 allows determination of what Step 1 needs to deliver to support this.

Version

V1.00 - This is the final version of the report produced by the PTC Issue Management Group and reviewed by the B4.2 team. Supported by the SJU.

Contributor(s)

Jorge Blanco (AENA/P5.7.2), Christian Bousmanne (ECTL/B4.2), Jerome Delapeyronnie (Thales/P10.2.3/P10.3.8), Cedric D’Silva (Thales/B4.2), Daniel Ferro (Airbus/B4.2), Joseba Garay (AENA/P5.7.2), John Godsell (NATS/P4.7.3), Elke Groeneveld (DFS/B4.2), Olivier Huart (Skyguide/4.2), Michel Le Toullec (Airbus/B4.2), Mats Lindholm, (SAS/B4.2), Andy Milligan (NATS/5.2), Daniel Nelson (NATS/B4.2), Franz-Josef Neumann (Thales/B4.2), Antonio Obis (AENA/B4.2), Luis Pérez (AENA/P5.7.2), Tord Pola (P8.3.10), Florénce Serdot-Omer (DSNA/4.2), Lars Stridsman (NORACON/B4.2), Philippe Trouslard (DSNA/B4.2)

B 4.2 Solution Rapporteur

Daniel Nelson (NATS)

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TABLE OF CONTENT

1 INTRODUCTION............................................................................................................................ 31.1 CONTEXT.......................................................................................................................... 31.2 SCOPE OF THE ACTIVITY....................................................................................................31.3 PARTICIPANTS................................................................................................................... 31.4 PURPOSE OF THE REPORT.................................................................................................41.5 PROCEEDINGS.................................................................................................................. 4

2 DIVERGING VIEWS ON PTC........................................................................................................53 DEVELOPMENT OF THE DEFINITION........................................................................................6

3.1 CLEARANCE PROVISION.....................................................................................................63.1.1 Definition of Clearance................................................................................................63.1.2 Clearance of Trajectory...............................................................................................63.1.3 Clearance of Manoeuvre.............................................................................................73.1.4 Clearance for a Segment of the Trajectory..................................................................83.1.5 Clearance for closed loop deviation from the Trajectory.............................................83.1.6 Clearance for open loop deviation from the Trajectory................................................93.1.7 General conclusion on Clearances...........................................................................10

3.2 SEPARATION ASSURANCE................................................................................................103.2.1 The ICAO Conflict Management layers.....................................................................103.2.2 Precision Navigation.................................................................................................103.2.3 Managing Separation through the RBT.....................................................................113.2.4 Conclusions...............................................................................................................12

3.3 COMPLEXITY MANAGEMENT.............................................................................................16

4 CONCLUSIONS ON “PTC”........................................................................................................174.1 PTC IN STEP 2...............................................................................................................174.2 PTC IN STEP 1...............................................................................................................174.3 PTC OI STEPS...............................................................................................................18

5 REFERENCES............................................................................................................................. 20

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1 Introduction

1.1 ContextA current activity of the WP B4.2 is the coordination of work to resolve concept level issues and questions raised by the X.2 and primary projects.In order to develop an efficient and transparent solution with all of the concerned stakeholders, a specific process has been set in place and has been followed, as test bed during this exercise.This process is summarised in the document ConOps Issue Management Process available on the SJU Extranet:

SESAR Joint Undertaking Programme > WP B > Project B.04.02 > Other Documentation > CONOPS > 06 - CONOPS Issue Management > CONOPS Issues > 12. Definition of Precision Trajectory Clearance (PTC)

1.2 Scope of the activityAs decided within the WP B4.2, this activity addresses the following issue:

Definition of “Precision Trajectory Clearance” (PTC).

At the time this Issue was launched (September 2012) there was no common agreement on the purpose of PTC. The DLT2.2.2 [1], states that “Successive segments of the RBT will be cleared”. In which case, each segment requires a clearance e.g. PTC when/where required. However, the concept has since been developed further as indicated in the ConOps Step 2 Guidance Paper, which states that “The RBT constitutes the clearance for the whole trajectory”. In Trajectory-Based Operations, the SBT and RBT data will be considered in relation to other SBTs and RBTs for Demand & Capacity Balancing (DCB) before final agreement but the RBT cannot be guaranteed conflict-free. The RBT is supported by a Revision process, whereby any new agreement will need to be conflict-free within the conflict horizon (/separation provision layer horizon), so how does PTC now apply?

Details on initial concerns as introduced are available in the ISSUEs library the SJU Extranet.

Scoping assumptions

The issue is addressed in the context of the SESAR STEP 2 timeframe, where the trajectory and the technology implementing the RBT have reached a mature stage. The group considered that it is more appropriate to converge on the final concept and data elements, and then to describe how this could apply in Step 1 considering the possible limitations which may affect this Step.

Anticipated technological capabilities for Step 2 will be captured as part of the broader “Trajectory Specifications” Issue Management and need not be further considered here.

1.3 ParticipantsAll X.2s and the Primary Projects that contain PTC within their scope (P4.7.3 & P5.7.2) were informed and invited to participate in the working group.

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1.4 Purpose of the reportThis report reflects the conclusions of the issue team. The solution will be agreed within this group then reviewed and adopted by the B4.2 team.

1.5 ProceedingsA series of WebExs whereby the group can discuss latest thinking and any supporting material provided.

19 September 9.30 – 11.30 5 October 9.30 – 11.30 19 October 13.30 - 15.30 5 November 13.30 – 15.30 19 November 14:00 – 16:00

Supporting material to be developed and provided as per meeting actions agreed by the group.

Delivery of final report 27 November 2012

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2 Diverging views on PTCThere are multiple uses of the term PTC detected across the SESAR documentation. In particular, PTC has been referred as:

- A ground based separation mode applicable in Trajectory Based Operations (TBO) environment.

- Closed loop clearances provided by the ground segment in new separation modes for TBO.

In SESAR D3 document, Precision Trajectory Clearances are included as elements of the new ground based separation modes, where the ATC service provider is responsible for the separation. Other elements, as Constraint management or Controlled times for queue management purposes, were associated to these separation modes.

SESAR B4.2 TMF document, which relates to SESAR Step 3, states: “A new ground based separation mode is the Precision Trajectory Clearances (PTC). A PTC relies on the de-confliction of flights and consists of the Controller issuing a long duration clearance to proceed on a 2D/3D trajectory to be flown by the aircraft using improved navigation performances (2D RNP, improved VNAV or VRNP)”.

SESAR B4.2 ConOps step 1 states “The use of data link allows Controllers to issue long duration and/or complex clearances through multi sectors (for example 2D PTC based on Pre-defined 2D routes with required navigational performance (2D RNP) [CM-0601]).”

Projects 4.7.3 and 5.7.2 propose PTC as a closed loop revision1 of the RBT as a consequence of a conflict assessment in the conflict horizon2 (which may be variable depending on the available tools and applied procedures) – the definition and purpose of PTC is dependent on the definition & scope of RBT.

In order to facilitate the PTC Concept understanding, a single use of this term is recommended.

1 Given that the RBT is a 4D trajectory, the revision may be applied on any of its dimensions.2 Please note that conflict horizon as is defined in ICAO 9854 is associated to separation provision layer

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3 Development of the definitionThere are three areas that have been associated with the concept of PTC:

1) Clearance provision

2) Separation Assurance

3) Complexity Management

In the following sub-sections, each one is explored to see how it would be provided in the Trajectory Based Operations environment of SESAR Step 2. The output of this analysis determines whether there is a need for a distinct “PTC” concept and, if so, what the scope of it is.

3.1 Clearance Provision3.1.1 Definition of ClearancePTC contains the term “Clearance” but this term is not commonly understood within the SESAR concept development.

The term “clearance” has a particular meaning for flight crew and controllers so an agreement is needed on the phraseology expected of controllers, of pilots and of the ground and air systems as part of the new concept. The Issue Management group should aim to define this.

In the current context, the ICAO PANS-ATM [2] defines a clearance as an abbreviation of:

Air traffic control clearance. Authorization for an aircraft to proceed under conditions specified by an air traffic control unit.Note 1.— For convenience, the term “air traffic control clearance” is frequently abbreviated to “clearance” when used in appropriate contexts.Note 2.— 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.

In the SESAR concept development context, the term “Clearance” is applied to multiple instances:

1. Clearance of Trajectory (e.g. RBT)2. Clearance of manoeuvre (e.g. departure/climb/descent) 3. Clearance for a segment of the trajectory (e.g. 3D SID)4. Clearance for closed loop deviation from trajectory (e.g. revising RBT)5. Clearance for open loop deviation from trajectory (e.g. heading to avoid conflict)

Differentiation is needed between the multiple possible uses of the term “clearance”. This may mean the definition of new terms applicable for the SESAR concept, for example “agreement” or “trajectory clearance”. Any new terms should be considered for fit within the current ICAO definition. Some types, as listed above, may be deemed not applicable to the SESAR concept.

3.1.2 Clearance of Trajectory

The SESAR ConOps Step 2 Guidance Paper states that:

The RBT constitutes the clearance for the whole trajectory… ATC clearances are NOT given by segments.

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However, the ICAO ATM Operational Concept [3] states that a trajectory is an “agreement” but not a “clearance”:

Clearances will allow the incremental delivery of the trajectory by the ATM system based on the assignment of traffic. Therefore, although the flight deck and the ATM system will have entered into a “gate-to-gate” agreement, that agreement will be actively affirmed by the delivery of each portion of the trajectory as a clearance.

So, in ICAO terms, the pilot has a trajectory that ATC has agreed to facilitate but he still needs incremental ATC clearances to fly the trajectory (here the ‘portion’ is not defined as manoeuvre or segment). The need for this is explained in Understanding Trajectory Management [4]:

Whilst the System therefore will be theoretically capable of identifying conflicting flights for the entire duration of the flight it will only certify that the track is conflict free out to the limits of what is considered reliable. This dimension has yet to be determined but will constitute the boundary for the ‘progressive clearance’ concept. Briefly, if no alerts are displayed then all concerned flights are ‘cleared’

The ICAO definition and initial SESAR definition are based on the principle of clearing trajectories in stages. However, this concept is challenged because it undermines the significance of the RBT ‘agreement’ and creates additional workload for controller and pilot. If the entire trajectory is cleared – in the same way that a flight is cleared to destination today – this does not mean that it is guaranteed conflict-free, but it shall be monitored for separation within the moving conflict horizon with separation action through an RBT Revision only taken when a potential conflict situation is detected.

The RBT constitutes the agreement that airspace user agrees to fly and the ANSP and Airports agree to facilitate. The SBT is passed from the FOC to be the RBT for the flight crew but this is not yet a clearance. ATC provides a departure clearance for the RBT; this fits within the ICAO PANS-ATM definition of ATC clearance.

The content of a departure clearance is defined in ICAO PANS-ATM [2]:

6.3.2 Standard clearances for departing aircraft 6.3.2.3 CONTENTS Standard clearances for departing aircraft shall contain the following items: a) aircraft identification; b) clearance limit, normally destination aerodrome; c) designator of the assigned SID, if applicable; d) initial level, except when this element is included in the SID description; e) allocated SSR code; f) any other necessary instructions or information not contained in the SID description, e.g. instructions relating to change of frequency.

If some, or all, of these aspects are included in the RBT, then the actual clearance phraseology could be simplified, but this is considered external to the scope of the PTC Issue Management topic.

With a flight cleared for the RBT, this means that, in the case of radio failure, the pilot will follow the RBT. This provides predictability for the pilot and the ground actors.

Conclusion:The RBT constitutes an ‘agreement’ for the whole trajectory; Departure clearance provided by ATC will include clearance for RBT(/RMT). Further clearances and/or ATC Instructions will be provided as necessary.

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3.1.3 Clearance of Manoeuvre

This is the current-day use of clearance (as per the ICAO PANS-ATM [2]): Taxi, Take-off, Departure, En-route, Approach or Landing, which includes climb/descent clearance as part of them. The climb/descent clearances may be single or multiple. For example, in the departure phase, a flight may be cleared to its cruise level or may be consecutively cleared to intermediate levels prior to the cruise level.

A clearance is issued from ATC to the pilot to fly following certain precision navigation trajectory parameters, which determine a separation mode:

i. Precision Trajectory parameters can be chosen by AUs from its actual capabilities and proposed to the ATC for agreement.

ii. Precision Trajectory parameters can be selected by ANSP depending on operational circumstances, predefined scenarios, and ANSP Capabilities and AUs to choose which most adapt its needs and possibilities to comply with.

Such clearances could still apply under ICAO ATM Operational Concept [3], which does not clarify what the clearance of “portions” pertains to.The RBT is the ‘agreement’ communicated as part of the Departure Clearance. The Departure Clearance is one aspect of the ICAO ATC Clearance definition; the other aspects of the ICAO ATC Clearance definition also still apply: “take-off”, “approach”, “landing”, etc

3.1.4 Clearance for a Segment of the Trajectory

Clearance by segment is as indicated in the SESAR Definition Phase (DLT2.2.2) [1]:

Successive segments of the RBT will be cleared.Clearance by segment is a potential alternative to clearance of manoeuvre (3.1.3). In this instance, consecutive 3D clearances are given for successive segments of the agreed trajectory. For example, in the departure phase, a flight may have intermediate levels prior to the cruise level but, if this is treated as one segment, then the clearance may be given for the entire climb phase of the trajectory with no additional clearances required for each step of climb.

An authorisation is issued from ATC to the pilot to proceed under a defined separation mode during a segment of the RBT.

This type of clearance is seen as not applicable to the SESAR ConOps, which has been further developed since the Definition Phase.

The RBT forms the ‘agreement’ of the trajectory (ATC agrees to facilitate and AU agrees to fly); any change to this will be managed as part of the RBT Revision process, so no clearance by segment is necessary.

Conclusion:This current-day use of ‘clearance’ (as per the ICAO PANS-ATM) remains.

Conclusion:This type of clearance is seen as not applicable to the SESAR ConOps.

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3.1.5 Clearance for closed loop deviation from the Trajectory

SESAR primary projects 4.7.3 & 5.7.2 propose PTC as:

A closed loop revision of the RBT as a consequence of a conflict assessment in the conflict horizon.

The SESAR ConOps Step 2 Guidance Paper states that:

In case of change, [the trajectory requires] RB/MT revision involving the pilot and controller.

From this, it can be deduced that a closed loop revision of the trajectory is managed by the RBT Revision process; therefore, the PTC as described by P4.7.3 & P5.7.2 is also part of the RBT Revision process.

The RBT Revision process will be implemented via ATC clearances/Instructions, which may be via either Datalink or voice.

Closed loop revisions of the trajectory apply in SESAR ConOps and, if the RBT constitutes a clearance, then an RBT revision is also a revision of the clearance. As highlighted in the analysis of point 1 above, it may be necessary to consider the RBT as an “agreement” – in this case the RBT Revision would be a revision of the agreement.

In the case of radio failure, the pilot will follow the revised RBT (i.e. the latest agreed RBT).

The ICAO ATM Operational Concept [3] states:

In a free-routing environment, a clearance or authorization to deviate or amend trajectory will not be required.

This seems not to be in alignment with the SESAR concept of RBT Revision but the ICAO concept assumes a Self-Separation mode environment, in which the ground actor is not responsible for separation. Therefore, there is no misalignment. In SESAR, Free Route refers to the ability to plan a flight without any reference to a published ATS route network. Free Route environment is not associated to a dedicated separation mode and, as in “conventional airspace” the flight crew is not allowed to deviate from his initial trajectory without an ATC clearance

3.1.6 Clearance for open loop deviation from the Trajectory

SESAR ConOps Step 1 still anticipates the need for Open Loop revisions:

“Open-loop” instructions are still used by Controller in time critical situations e.g. to ensure immediate separation of the aircraft versus conflicting traffic or to avoid adverse weather (CBs).

As defined in the ConOps, and in accordance with the ICAO PANS-ATM [2], these can be termed “ATC Instructions”. During the Execution Phase of a Flight, a tactical modification to the agreed parameters of the RBT might be issued by ATC for a separation purpose that leads to an Open loop on the trajectory. Open loops are the last resort of ATC for separation purposes. Closed Loops are preferred and recognised as the optimum procedure and are integrated in the Trajectory Revision Process.

Conclusion:All closed loop trajectories / flight paths are part of the RBT and are managed through the RBT Revision process. This results in a revision of the ‘agreement’ that the pilot is cleared to fly (noting that clearances for specific manoeuvres - as per the ICAO PANS-ATM – are still required)..

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There may always be a need for open-loop ATC instructions to manage time critical situations but this means that the RBT has been suspended until the flight can be put back on the original, or a revised, trajectory. Therefore, these should not be considered further in the development of PTCs.

If the RBT is suspended, it means that there is no update to the RBT data set from the airborne predicted trajectory and no use of the RBT data in the ground prediction tools, until the RBT is re-instated when closed-loop operations resume. Whilst the RBT is suspended, separation management will be based on the data in the ground systems.

3.1.7 General conclusion on Clearances

3.2 Separation Assurance3.2.1 The ICAO Conflict Management layersThe ICAO ATM Operational Concept [3] identifies conflict management process in three layers:

a) strategic conflict management;b) separation provision; andc) collision avoidance.

(a) Strategic Conflict Management will be mainly used prior to departure but it won't be limited to this period. Due to the nature of the Strategic Conflict Management layer and the tools it can make use of, it is presumable to believe that conflicts appearing once the aircraft is in flight will be detected and solved by the second layer. However, the number of in-flight appeared conflicts may be significantly reduced as long as Traffic Synchronization techniques are appropriately used. This layer could relate to RBT and SBT processes.

(b) Separation Provision layer will be used when Strategic Conflict Management layer cannot prevent the appearance of conflicts or a greater degree of accuracy is required to reduce uncertainty. Conflict detection and resolution tools are expected to provide improved accuracy to separation management over Traffic Synchronisation alone. Conflict detection and resolution tools will be used in order to detect and solve any conflict. This layer could relate to RBT processes.

(c) Similarly to above, Collision Avoidance layer will only act, although it will be continuously checking in the shadow, when Separation Provision Layer has not worked in the expected manner, this is, the separation mode has been compromised and a separation minima infringement has occurred or is about to occur. This means that the Separation Provision layer has failed in its duty. The Collision Avoidance layer is covered by Safety Nets.

Conclusion:Clearances will still be provided in accordance with the ICAO PANS-ATM document

Conclusion:All open loop deviations from the trajectory are based on ‘ATC instructions’ (except for collision avoidance instances when ACAS or ground proximity warning systems take primacy and distress/emergency situations). In Trajectory based operations, such deviations have to be avoided as far as possible.

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3.2.2 Precision NavigationPrecision navigation corresponds to the “required navigational performance” associated to the routes and altitude or time constraints part of SBT/RBT.

In the lateral dimension, the “required navigational performance” corresponds to the RNP value associated to the airspace or the routes i.e. the Pre-defined or User-preferred routes, or portion of routes, part of SBT/RBT during planning or revised during execution. According to ICAO 9613 PBN manual [5], RNP provides accuracy, integrity and continuity in lateral navigation with high level of reliability and very few risks it will not be achievable by avionics, including on-board performance monitoring and alerting regarding RNP specified limits.

Depending on aircraft capabilities in steps 1&2, RNP will provide more deterministic Fixed Radius Transition (FRT) and scalable fixed RNP values defined per segment leg. In en-route (e.g. A-RNP 1), and deterministic Radius-to-Fix turn (RF) in TMA (e.g. RNP0.3).

Regarding the vertical dimension, it is not possible to constrain the vertical profile in a 3D tube in steps 1&2 like constraining the lateral profile in a 2D corridor thanks to 2D RNP. The DLT2.2.2 [1] mentions the Vertical RNP (VRNP) but such a concept has still to be defined and the corresponding capability is not expected before step 3. So, only indication on accuracy along the vertical profile and at altitude constraint can be provided. According to AC-20-138, consensus estimates based upon experience and some limited testing indicate that

flight technical errors along a specified 3D profile can be expected to be less than 200ft below 5000ft and 300ft above 5000ft on a three sigma basis

and to intercept a specified altitude to be less than 150ft below 5000ft and 240ft above 5000ft on a three sigma basis

Note that if the use of minimum required thrust setting normally idle thrust in descent phase (optimum CDA) will generally offer enough margin to stick to the reference 3D profile of RBT, the use of operator’s preferred thrust and speed setting generally close to maximum thrust in climbing phase (optimum CCD) will offer less margin to stick to the reference 3D profile of RBT, leading to potential deviation.

Regarding the time dimension, the “required navigational performance” associated to a time constraint set on a fix of RBT or revised RBT is CTO or CTA achievable by avionics according to the required accuracy of +/-30 seconds or +/-10 seconds 95% of the time. It is not possible to constrain the time along a whole segment of the trajectory in steps 1&2. The DLT2.2.2 [1] mentions the “4D contract” but such a concept has still to be refined and the corresponding capability is expected beyond step 3. Only indication on time accuracy along the trajectory can be provided i.e. it is a % of the time horizon e.g. +/-18’’ at 20’ if winds do not change.

So, regarding separation, the precision navigation capabilities in steps 1&2 will allow the de-confliction of 3D profiles of RBT using 2D RNP and/or altitude constraints set on crossing profiles and/or time constraints set on merging points, not more.

3.2.3 Managing Separation through the RBTAt RBT instantiation, the RNP accuracy requirements for each trajectory segment in RBT could allow some initial trajectory deconfliction.However, despite an Aircraft being cleared to fly the “trajectory” (planned route) from the departure to the destination, it cannot be assured that the future flight path will be free of conflicts. The assurance of separation provision along the whole planned route is limited due to the Conflict Horizon3 of the tools available.

What can be assured is that the flight path generated by the RBT is conflict free within the available Conflict Horizon. This conflict horizon initially starts at the beginning of the RBT and

3 Conflict Horizon: The extent to which hazards along the aircraft’s future trajectory are considered for separation provision.

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keeps moving along as a sliding horizon as flight advances. The horizon is variable depending on the phase of flight, ground tools, procedures, actors and navigation specifications.

The P4.7.3 & P5.7.2 need guidance on whether the information contained in the RBT is enough to provide Trajectory Based Separation (in terms of accuracy, profile definition) e.g. inclusive of Fly-over/Fly-by, RF turns, etc. For example, Airbus FMS uses “fly-by” by default but not all manufacturers behave in the same way. In order to analyse a future scenario in terms of conflict detection and resolution, P4.7.3 & P5.7.2 believe that it is needed to know the way in which the aircraft will fly the RBT.

Except for CFIT, during ACAS RA manoeuvres and under specified ASAS manoeuvres, Separation Assurance remains the responsibility of the Air Traffic Service provider. The new separation mode proposes to allow the controller (EC, PC, MSP) to extend the time to respond to conflicts by providing him a set of supporting tools, which will be based on an improved trajectory prediction. This trajectory prediction would include elements provided by both the aircraft and ground-based tools. Thus, the controller would be alerted to conflicts that today they are not. Since this is an early detection, the planner controller may initiate a revision of the trajectory to avoid the conflict without creating new ones,

Any new separation mode will principally be based on the use of closed loop revisions of the agreed RBT. In order to operate as described, the following scheme needs to be followed:

1. Conflicts need to be detected.2. A solution to avoid the conflict needs to be found and agreed among involved

stakeholders.3. The solution needs to be implemented4. Once it has been implemented, the execution of the solution needs to be

monitored.

Any closed loop revision is part of the new agreed RBT. The revised routes/constraints are checked by the Flight crew and loaded in FMS for activation of the revised RBT on-board; EPP is then automatically down linked for consistency check (new revised routes/constraints effectively entered in FMS) and for improvement of ground tools with aircraft trajectory predictions e.g. separation management tools.

All needs, including those for Separation Management need to be included in the trajectory data set(s)4. By this is meant the set of data that is available through ground-ground SWIM to all relevant partners where aircraft air ground Datalink provide aircraft trajectory data. In addition to the data set, we have to consider related roles/responsibilities, mechanisms (including revisions), and temporality that will enable this data set to remain reliable and usable by all. The combination of:

[data + responsibilities + mechanisms]

should be able to feed/support all tools/service needs, including the separation services.

3.2.4 ConclusionsThere are two key elements to consider for separation management – agreed by the group:

(1) Monitoring Separation

Except for CFIT avoidance manoeuvres, during ACAS RA manoeuvres and under specified ASAS manoeuvres, Separation Assurance remains the responsibility of the Air Traffic Service provider. There needs to be accurate data to feed the ground system predictors so that separation can be predicted and monitored; this will come air/ground

4 The RBT is a current state of definition, and a priori not self-sufficient until primary projects confirm/validate not only use of RBT, but also its content/operation mode.

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from the EPP and also via SWIM, e.g. from the Flight Operations Centre (FOC) or Network Management Function (NMF).

a. The full set of parameters needed to monitor separation has not yet been defined; these should be identified and validated at primary project level.

b. Once the set of parameters are known, it should be determined where each will come from: EPP,SWIM, local monitoring, radar tracking, ADS-B, etc – This is dependent on the output of B4.2 Trajectory Specifications Issue Management.

c. If additional parameters are required than those identified in the Flight Object, then these results should be passed to X.2s/B4.2 for consideration of concept update.

d. With respect to long duration clearances, the consistency of separation applied by the different ground actors (Multi-Sector Planner (MSP), Executive Controller (EC)) is to be assessed at primary project level: the separation minima is a set value but the uncertainty will vary for each actor, e.g. the MSP “picture” will be less accurate than the EC one.

(2) Managing Separation

If separation monitoring determines that separation minima will be infringed, then action will need to be taken via the RBT Revision process.

a. The RBT Revision process is the correct method for ATC to use to provide instructions to the flight in the case of separation management because it is the process for closed loop trajectory management - it will be fully defined as part of the B4.2 Trajectory Specifications Issue Management.

b. The scope of action to be taken to manage separation via the RBT process is to be assessed and validated by the primary projects, for example in step 2:

i. Addition of intermediate waypoint(s) as determined by the ground systemii. Lateral revision of waypoint(s)iii. Application of level constraints to waypoint(s)iv. Application of speed control/constraints

c. If the identified potential actions to be taken to manage separation cannot reasonably be managed within the scope of the EPP, as defined by WG78/SC214 standard, then these results should be passed to X.2s/B4.2 for consideration of concept update. Additional technical and/or standardisation enablers may be required.

d. ATSU to avoid adding intermediate waypoints to an already defined trajectory if only to get improved accuracy of predicted trajectory. Although this is not a strict principle from the concept documentation, it is a principle to only constrain flights by exception. To be assessed by Primary Projects.

See Figure 1 & Figure 2 below.

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ICAO procedures state that (Annex 11 – 3.5.2) “Responsibility for the control of all aircraft operating within a given block of airspace shall be vested in a single air traffic control unit. However, control of an aircraft or groups of aircraft may be delegated to other air traffic control units provided that coordination between all air traffic control units concerned is assured.

Consequently, long duration clearances implies proper coordination procedures (automated or not) between the “control units” involved (FO could be an enabler). This has to be addressed by primary projects.

Conclusion:Primary Projects to identify and validate the full set of parameters needed by the ATSU ground system to monitor separation.

Conclusion:Primary Projects to assess and validate the scope of action to be taken to manage separation via the RBT process.

Conclusion:The parameters and controls needed for Separation Management in a Trajectory Based Operation must be defined by the Primary Projects and then included/used in Trajectory Management; the flight object becomes the only trajectory representation containing sufficient data to be used in support of the corresponding conflict management tools to assure and monitor separation. Every requirement for separation purposes should be possible within the RBT revision. The RBT does not provide separation itself

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Figure 1 - accurate data to feed the ground system predictors so that separation can be assured; this will come air/ground from the EPP and also via SWIM (e.g. from the FOC and NMF).

Figure 2 - If separation cannot be assured, then action will need to be taken via the RBT Revision process.

SWIM

Ground Prediction Tools

Other data (tbd), e.g. fly-by/over

Network ManagerSO D

FOC

D-ATSUC-ATSU

N

EPP (waypoints & constraints)

RBT Revision Process

RBT Revision Process

SWIM

Ground Prediction Tools

Network ManagerF

FOC

D-ATSUGEG

C

C-ATSUN

EPP (waypoints & constraints)

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3.3 Complexity ManagementAt the B4.2/X.2 meeting on 25-26 OCT 12, it was agreed that there should be not specific "complexity management" process. Complexity will need to be managed but this will be done as part of already-defined processes, such as dDCB and INAP.

If changes to one or more trajectories are required as part of a process to manage complexity, then this will be managed via the RBT process, i.e. consider in a similar way to the Separation Assurance process.

Conclusion:Manage complexity via the RBT process.

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4 Conclusions on “PTC”

4.1 PTC in Step 2The conclusions on each of the three concept elements that PTC pertains to (Section 3) show that Clearance Provision, Separation Assurance (using Precision Trajectories) and Complexity Management are all incorporated in trajectory management processes: RBT instantiation, RBT Revision, etc. The RBT is a “precision trajectory” in that it may include “required navigational performances” associated to the Pre-defined or User-preferred routes or portion of routes of RBT (e.g. 2D RNP specifications and/or altitude constraints on specified points to ensure de-confliction of 3D profiles); the RBT may be revised using additional or amended lateral routes/waypoints and/or altitude constraints on specified points to ensure separation in execution phase. ATC clearances are included as part of the RBT Revision process. Therefore, there is no additional, specific concept element needed, the notion of PTC is implicitly covered by 4D trajectory management process.

There is not yet a complete definition of all of the trajectory management processes at the B4.2/X.2 level but these are in development through other B4.2 Issue Management processes. In the interim, there is a clear set of assessment and validation activities that Primary Projects need to carry out in relation to the Separation Assurance concept element (identified in Section 3.2.4))

It is recommended that the use of the term “PTC” be discontinued because it has a specific meaning from the DLT2.2.2 concept [1], which is no longer deemed applicable.

The definition of “Precision Trajectory” should be added to the SESAR Integrated Dictionary:

A trajectory that includes required navigational performances associated to the Pre-defined or User-preferred routes, or portion of routes, of trajectory (e.g. 2D RNP specifications and/or altitude constraints on specified points to ensure de-confliction of 3D profiles).

4.2 PTC in Step 1As per Step2, in Step 1, clearances will be provided in accordance with ICAO definition of ATC Clearances.

In Step 1, airspace or routes will have associated 2D RNP specifications to manage separation. The 2D RNP specifications of an airspace or route cannot be changed but different routes can be assigned.

In Step 1, there will be Free Routing for flights in cruise and vertically evolving, inside FAB above a certain level, within low to medium traffic complexity areas. Trajectories within this Free Route Airspace will be User-preferred and not based on Pre-defined routes. Free Route Airspace will have an associated required performance for navigation; 2D RNP specifications may be applied.

Separation management must be provided in Free Route Airspace but, in Step 1, RBTs are not part of the solution. Therefore, the Primary Projects should assess how separation can be managed in a Free Route environment without this concept. If new OI Steps are required, then a Change Request to the Integrated Roadmap should be raised accordingly.

Note: Advanced RNP is supposed to be mandated ECAC wise by 2020 i.e. RNP1 and more deterministic FRT (Fixed Radius Transition) in En-route, RNP1 and RF (Radius-to-Fix) in TMA. Lower RNP value (like RNP0.3 for final approach) cannot be envisaged in En-route and Descent due to higher speed than in Approach and so risk of overshoot when turning. Aircraft capabilities “by default” will be RNP1 and FRT in En-route, RNP1 and RF in TMA and any other RNP value appears inappropriate, so dynamic allocation of RNP seems therefore not justified. Today, RNP is specified for pre-defined routes in the aircraft navigation database, it will be specified for preferred route in Free Route Airspace (RNP1 and FRT) from agreed RB/MT at the gate and via CPDLC in case of revision due to separation purpose.

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4.3 PTC OI StepsThere are currently five OI Steps relating to “PTC”; these are as follows:

Step 1CM-0601 “Precision Trajectory Clearances (PTC)-2D Based on Pre-defined 2D Routes”

Step 2CM-0602 “Precision Trajectory Clearances (PTC)-3D Based on Pre-defined 3D Routes”

CM-0603 “Precision Trajectory Clearances (PTC)-2D On User Preferred Trajectories”

Step 3 - outside the scope of the PTC Issue Management topic

CM-0604 “Precision Trajectory Clearances (PTC)-3D On User Preferred Trajectories (Dynamically applied 3D routes/profiles)”

CM-0501 “4D Contract for Equipped Aircraft with Extended Clearance PTC-4D”

Propose that the following Roadmap Change Requests be raised as an output of this Issue Management report:

CM-0601 – Need to identify what is new in Step 1, based on Pre-defined route versus today. The key difference is the application of 2D RNP specifications to Pre-defined routes or User-preferred routes.

CR: Change the Title to “Separation Management using Pre-defined or User-preferred Routes with 2D RNP Specifications”Change Description to “2D Pre-defined or User-preferred routes, with their associated 2D RNP specifications, are allocated and re-allocated to assure separation. Vertical constraints on specified points and longitudinal separation is provided by ATC to complement the 2D route. This may be achieved through surveillance based separation and/or the application of constraints. New support tools (incl. MTCD) and procedures and working methods have to be put in place.User-preferred Trajectories/Revisions may include non-published waypoints that are computed by Ground tools (ideally based on information from the airborne system) and defined in lat/long or bearing/range”Truncate Rationale to: “The allocation of 2D routes is a deconfliction method with vertical and longitudinal separation (if required) provided by ATC to complement the 2D route. This may be achieved through surveillance based separation and/or the application of constraints (depending on available ATM capabilities).”

CM-0602 – This mode relies on aircraft capabilities enabling barometric vertical navigation (VNAV) with the required accuracy and ‘containment’ of the vertical profile. It is not possible to constrain the vertical profile in a 3D tube in step 2. The possibility to apply vertical constraints in complement to the 2D route is included in CM-0601 and CM-0603 for Steps 1 and 2 respectively. Vertical navigation is expected to be delivered in Step 3. As with the lateral navigation (CM-0601/CM-0602) this should apply equally to Pre-defined and User-preferred routes. Therefore, CM-0602 should be merged with CM-0604

CR: Remove the OI Step and combine with CM-0604 in Step 3:

Change the Title of CM-0604 to: “Separation Management using RBTs with 3D RNP Specifications”.

Change Description of CM-0604 to: “The RBT is a “precision trajectory” in that it may include required navigational performances associated to the Pre-defined or User-preferred routes of RBT. In Step 3, this includes 3D RNP

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specifications on specified points to ensure de-confliction of 3D trajectories. The RBT may be revised using additional or amended 3D routes/waypoints to ensure separation in execution phase; ATC clearances are included as part of the RBT Revision process. User-preferred Trajectories/Revisions may include non-published waypoints that are computed by Ground tools (ideally using information from the airborne system) and defined in lat/long or bearing/range.”Longitudinal separation is provided by ATC to complement the 3D route (based on a User-preferred Trajectory). This may be achieved through surveillance based separation and/or the dynamic application of constraints. New support tools and procedures and working methods have to be put in place. This mode relies of aircraft capabilities enabling the vertical containment of the trajectory (3D tube) and less of ATC tactical operations. E.2.6.2.3.1”

CM-0603 – In Step 2 we introduce the concept of the RBT (including the RBT revision process) using 2D RNP specifications.

CR: Change the Title to “Separation Management using RBTs with 2D RNP Specifications”Change Description to “The RBT is a “precision trajectory” in that it may include required navigational performances associated to the Pre-defined or User-preferred routes of RBT. In Step 2, this includes 2D RNP specifications and/or altitude constraints on specified points to ensure de-confliction of 3D profiles. The RBT may be revised using additional or amended lateral routes/waypoints and/or altitude constraints on specified points to ensure separation in execution phase; ATC clearances are included as part of the RBT Revision process. User-preferred Trajectories/Revisions may include non-published waypoints that are computed by Ground tools (ideally using information from the airborne system) and defined in lat/long or bearing/range.Vertical constraint and longitudinal separation is provided by ATC to complement the 2D route (based on a User-preferred Trajectory). This may be achieved through surveillance based separation and/or the dynamic application of constraints. New support tools and procedures and working methods have to be put in place. E.2.6.2.3.2”Leave this OI Step in Step 2 until primary project assessment determines otherwise. iRBT revision process is available in step 1. Therefore, the progression between the step 1 and step 2 OI steps has to be clarified by primary project assessment.

OI Step summary: CM-0601 Step 1: Separation Management using Pre-defined or User-preferred

Routes with 2D RNP Specifications CM-0603 Step 2: Separation Management using RBTs with 2D RNP Specifications CM-0604 Step 3: Separation Management using RBTs with 3D RNP Specifications

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5 References[1] SESAR Definition Phase D3 Concept of Operations, DLT-0612-222-02-00, October 2007

[2] ICAO Procedures for Air Navigation Services, Doc 4444 ATM/501, Fifteenth Edition - 2007.

[3] ICAO Global Air Traffic Management Operational Concept, Doc 9854 AN/458, First Edition – 2005.

[4] SESAR Understanding Trajectory Management, EA-WPB-EP2-03 -06-07-2009, 2009.

[5] ICAO Performance-based Navigation (PBN) Manual, Doc 9613 AN/937, Third Edition - 2008

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