1

The CREDOS Project

Deliverable D5-4

"Alignment of the CREDOS Concept with the SESAR Programme "

Abstract: The CREDOS project aims to demonstrate the feasibility of a departure operation whereby the wake turbulence separations between successive aircraft are temporary suspended under specific (favourable) crosswind conditions. This report considers the alignment of the aims of the CREDOS project with the SESAR target concept and work-programme.

Contract Number: AST5-CT-2006-030837 Proposal Numbe r: 30837

Project Acronym: CREDOS

Deliverable Title: Alignment of the CREDOS Concept with the SESAR Programme

Delivery Date: T30

Responsible: ECTL

Nature of Deliverable: Report

Dissemination level: Public

File Id N°: CREDOS_522_ECTL_DLV_D5-4_SESAR

Status: Final (Approved) Version: 1.0 Date: Februa ry 2009

Approval Status

Document Manager Verification Authority Project App roval

ECTL EUROCONTROL PMC

Andy Harvey MTM PMC members

WP5 Leader Coordinator

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Acronyms and definitions

Acronym Definition AMAN Arrival Manager ASAS Airborne Separation Assurance System ATC Air Traffic Control ATM Air Traffic Management CDG Charles de Gaulle, Roissy Airport CNS Communication, Navigation and Surveillance CREDOS Crosswind Reduced Departure Operations DMAN Departure Manager EC European Commission ECTL EUROCONTROL EOCVM European Operational Concept Validation

Methodology ICAO International Civil Aviation Organisation ILS Instrument Landing System IOC Initial Operational Capability IP Implementation Package KPA Key Performance Indicator LOC Line of Change NM Nautical Mile NOP Network Operation Plan OI Operational Improvement PMC Project Management Committee RBT Reference Business Trajectory SESAR Single European Sky ATM Research SID Standard Instrument Departure SMAN Surface Movement Manager SMGCS Surface Movement Guidance and Control (System) SWIM System-wide Information Management TBS Time Based Spacing TCAS Traffic Alert and Collision Avoidance System WIDAO Wake Independent Departure and Arrival

Operations WP Work Package WT Wake Turbulence WV Wake Vortex

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Executive Summary

This report evaluates the alignment of the CREDOS project with the SESAR Deployment and

R&D Programmes.

The CREDOS project started during the early planning of the SESAR programmes and will

finish in November 2009.

The evaluation was performed by comparing the CREDOS Concept of Operations with the

SESAR Target Concept. Other SESAR definition phase deliverables have also been

assessed to ensure that the work of the CREDOS project is aligned, and will be taken on

board once the CREDOS project is completed.

No major issues of alignment were found.

Some minor issues regarding the nature of the benefits of CREDOS and its requirements for

input data have been identified.

Some minor issues regarding the clarity of the scope of work to be performed in SESAR IP1

have been identified.

The primary recommendation, provided in the final section of this report, is to ensure that

there is adequate communication between CREDOS and the relevant actors in SESAR in

2009.

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Table of Contents

1 INTRODUCTION 5

1.1 BACKGROUND 5

1.2 OBJECTIVE 5

1.3 STRUCTURE OF THE DOCUMENT 6

2 OVERVIEW OF THE CREDOS CONCEPT 7

2.1 THE CONCEPT 7

2.2 CREDOS DEPARTURE PROCEDURE 8

2.3 WIND SPEED AND DIRECTION MONITORING 8

2.4 WAKE VORTEX DETECTION AND PREDICTION 8

2.5 OPERATIONAL VALIDATION OF CREDOS 9

3 SESAR TARGET CONCEPT 10

3.1 TRAJECTORY-BASED OPERATIONS 10

3.2 OPERATIONS ON AND AROUND AIRPORTS 10

3.3 CREDOS PERFORMANCE EXPECTATIONS 11

3.4 CONCLUSION 13

4 SESAR ATM MASTER PLAN 14

4.1 MASTER PLAN OVERVIEW 14

4.2 LINES OF CHANGE 14

4.3 CREDOS IN THE MASTER PLAN 15

4.4 METEOROLOGICAL DATA 16

4.5 DEPARTURE MANAGERS 16

4.6 CONCLUSION 16

5 SESAR WORK PROGRAMME 2008-13 17

5.1 OVERVIEW OF THE SESAR WORK PROGRAMME 17

5.2 IP1 OPERATIONAL IMPROVEMENTS RELATING TO CREDOS 17

5.3 IP2 OPERATIONAL IMPROVEMENTS RELATING TO CREDOS 18

5.4 IP3 OPERATIONAL IMPROVEMENTS RELATING TO CREDOS 18

5.5 TREATMENT OF THE WAKE TURBULENCE ISSUE IN SESAR 19

6 SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS 20

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1 Introduction

1.1 Background

The CREDOS Project was launched officially in June 2006, based on a Description of Work

(DoW) developed over the previous 18 months. Following on from the encouraging results of the

S-Wake and ATC-Wake projects, the aim of the CREDOS Consortium was to define a project to

focus on a specific operational situation in order to demonstrate the real-world feasibility of

reduced wake turbulence separations.

The crosswind condition was chosen because of the relative ease of measurement; and the

departure situation was chosen because it was believed to be easier to demonstrate from a

safety point of view. Most importantly, CREDOS would be the first project to undertake a large

campaign of measures of wakes from departing aircraft.

Thus the CREDOS project evolved from previous research activities and was defined primarily as

an R&D project.

Although the SESAR initiative was being discussed even before the first drafts of the CREDOS

project proposal were written, it was only after the start of the CREDOS project that SESAR has

developed into a full program. Thus the CREDOS project was established without any knowledge

of the possible content of the SESAR future work. Although CREDOS has proceeded somewhat

independently of SESAR, every opportunity has been taken by the CREDOS Consortium and the

EC to ensure that details of the CREDOS project are included where appropriate in the SESAR

Definition Phase.

Conversely, and within the bounds of the agreed DoW, the CREDOS consortium has attempted

wherever possible to ensure that the work performed in the project support the goals of the

SESAR project. This document itself replaces a CREDOS Marketing Plan which, in the light of

the emergence of the SESAR initiative, was considered redundant.

1.2 Objective

The purpose of this report is to assess the alignment of the CREDOS project and the CREDOS

Concept of Operations with the key documents of the SESAR Definition Phase, namely the

SESAR Target Concept (D3), the SESAR Master Plan (D5) and the SESAR Work Programme

(D6).

The report will identify the possible contributions of the CREDOS work to the SESAR

Development Phase, as well as any conflicts or mismatches which could be rectified during the

remainder of the CREDOS project life.

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1.3 Structure of the document

Section 2 provides an overview of the CREDOS Project and the Concept of Operations it aims to

validate. This concept is then compared in section 3 with the SESAR Target Concept as

described in SESAR Deliverable D3.

Sections 4 and 5 contain a review of the SESAR Master Plan (D5) and Work Programme (D6)

respectively, with regard to the alignment of CREDOS with these two SESAR documents.

Section 6 provides a conclusion to the study, along with a summary of the alignment issues

identified and any necessary actions to remedy these.

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2 Overview of the CREDOS Concept

2.1 The Concept

The CREDOS concept is based on the authorised suspension of wake turbulence separations

between pairs of departures, if certain wind conditions are met. These conditions concern the

strength and direction of the wind on the runway and during the initial part of the climb phase

(typically up to 1500 ft above ground).

Compared to the current ICAO wake turbulence separations of 2 min for HEAVY – MEDIUM

pairs, the separation minimum target for the CREDOS concept is approximately 1 minute or the

equivalent radar distance separation of 3 NM. Such separation minima would be applicable from

rotation until the standard en-route separation is established (e.g. 5 NM).

As an illustration, Figure 1 shows the case of a MEDIUM aircraft taking off behind a HEAVY on

the same SID. It is seen that the crosswind is strong enough to blow the wake vortices generated

by the preceding aircraft, out of the track of the follower, for the take-off phase and the initial climb

phase. In this case, wake turbulence separation can safely be suspended during these two

phases. Beyond the suspension separation area (shown as the blue area) the standard ICAO

radar wake turbulence separations should be applied.

Figure 1: Illustration of the CREDOS concept of ope ration. Case of a MEDIUM aircraft

following a HEAVY on the same SID. A top view (A) a nd a side view (B) are shown.

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2.2 CREDOS Departure Procedure

The CREDOS departure procedure applies, under favourable crosswind conditions, a time

separation for consecutive departures from the same runway which is independent of their Wake

Turbulence Weight Category. This time separation is smaller than the ICAO WT separation

minima which must be applied under current operations when (i) a Heavy is followed by a

Medium or Light, or (ii) a Medium is followed by a Light aircraft;

The scope of the departure procedure for CREDOS covers the runway and initial departure

phases of flight. It includes the various separation minima that are to be applied on the runway

and (for radar environments) extends up to the altitude at which the standard radar separation for

area control is to be obtained.

2.3 Wind Speed and Direction Monitoring

In order to guarantee the safety of departure operations during the application of CREDOS

separations, the wind speed and direction have to be monitored in real-time for the area that

encompasses the departure path up to the altitude where standard separation for area control is

to be obtained.

Furthermore the concept requires that the SID to be used by the leader and the follower aircraft,

be examined in order to determine whether CREDOS separation should be applied. The initial

climb segment of the follower aircraft must be on the same track or upwind compared to the track

of the leader aircraft.

2.4 Wake Vortex detection and prediction

The CREDOS concept is expected to bring some benefits when applied at airports with typical

current configurations of meteorological sensors. Extensive measurements of weather and wake

vortex relationships have been undertaken as part of the research effort, but it is not expected

that wake vortex detection will be required during operational use of CREDOS. However, in order

to meet the requirement to provide a safety monitoring system, the use of a WV detection system

(occasionally or permanently) may be required.

The rate of application of CREDOS will depend on the quality of the meteorological data available

and so could be improved if airports become equipped with better sensors and analysis models.

Likewise there is no requirement for the use of WV behaviour models in an operational use of

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CREDOS. CREDOS requires only a map of the prevailing winds in the volume of interest.

However, if WV behaviour models are available and tuned to the local airport environment, this

would reduce the size of the required safety margins and so increase the applicability.

An ideal configuration for a very busy airport might include a WV detector used both for safety

monitoring and to train a WV predictor model.

2.5 Operational Validation of CREDOS

CREDOS assumes that under suitable wind conditions no additional wake turbulence separation

in time or distance is needed because any hazardous turbulence will be transported out of the

track of the following aircraft. The validation of CREDOS will determine what the wind variation,

direction and strength shall be in order to provide these suitable conditions.

It also has to be proven in the validation of CREDOS that the use of different tracks (SID) in

crosswind conditions is safe, and that the use of a same or upwind track by the following aircraft

is operationally viable.

In terms of increased throughput, the CREDOS concept is most beneficial when a runway is used

in segregated mode i.e. one runway is used for departures and another for arrivals. However

CREDOS can be applied between any two consecutive departures if all CREDOS safety

requirements are met.

The CREDOS concept does not aim to reduce or suspend any standard separation aimed

at separating aircraft from each other in order to avoid the risk of collision.

It is also important to note that, because of its dependence on the presence of suitable winds, the

increase in departure capacity provided by CREDOS, cannot be guaranteed. Thus it is unlikely

that the use of CREDOS will lead to an increase in declared departure capacity. The real benefit

of CREDOS will only be seen in situations where a departure queue has built up. In such cases,

CREDOS provides ATC will the possibility to temporarily augment the departure rate, if the

meteorological conditions are suitable.

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3 SESAR Target Concept

3.1 Trajectory-based Operations

The SESAR target concept of operations is described in SESAR deliverable D3. It represents a

shift from current airspace-based operations to trajectory-based operations and focuses on the

following elements:

• 4D trajectory management, centred around the idea of the Reference Business

Trajectory (RBT)

• Collaborative Network operation planning, managed through the Network Operation Plan

(NOP)

• Integrated airport operations

• New separation modes

• System-wide information management (SWIM)

• Human role as managers and decision-makers

Airport Integration is considered key to the SESAR ConOps, with the ground phases of flight

becoming a full part of the trajectory planning and execution. One key goal of the program is the

reduction of both ground and air queuing in order to reduce fuel and emissions, and so meet the

specified performance targets of D2.

3.2 Operations on and around Airports

The text below is adapted from the SESAR D3 document. Although there are references to the

wake turbulence issue throughout the document, the most specific references to CREDOS are

found in section 2.2.4.2.3 which addresses ‘Operations on and around the airport’.

Runway throughput must be optimised to achieve the airport capacity targets as defined in D2.

This requires a spectrum of measures ranging from long-term infrastructure development,

through realistic scheduling, demand and capacity balancing, queue management and runway

throughput improvements. The impact of adverse weather conditions must also be minimised.

Airports will be fully integrated into the ATM network, with particular emphasis being placed on

turnaround management, runway throughput and improved environmental performance. The

airport view of the ATM Target Concept is from the perspective of "en-route to en-route",

managing the aircraft turnaround and flight operation as a single continuous event. Sharing

turnaround information in a collaborative process will improve estimated times of subsequent

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events such as off-blocks and take-off.

The SMAN tool, to be developed within A-SMGCS, will determine the optimal surface movement

plans involving the calculation and sequencing of movement events and optimising resource

usage, while minimising the environmental impact. SMAN will collaborate with AMAN/DMAN to

establish the arrival and departure sequence.

Various techniques and procedures will be in place to increase runway throughput and utilisation such as:

• Reducing dependency on wake vortex separation by the re-classification of aircraft into a wider range of wake vortex categories, dynamic pair-wise separations considering prevailing wind conditions and stability of the air mass, improved prediction and

• detection of wake vortex; • Re-sequencing of the traffic flow to group similar categories of aircraft; • Minimizing runway occupancy time by runway and runway exit design improvements and

improvement of the procedures to vacate at an agreed turn-off whether supported by systems or not;

• Accurate and more consistent final approach spacing achieved by time-based separation taking into consideration wake vortex by either controller tools or onboard tools like ASAS;

• Reducing departure spacing by better wake vortex management, runway design and improved terminal area capacity;

• Optimising runway configuration/mode of operation in case of multiple runways; • Interlaced take-off and landing procedures (mixed mode operations); • Increased runway utilization during Low Visibility Conditions (LVC) by mitigating the ILS

signal disturbance issues and by tools to enhance ground controller and pilots’ situation awareness in low visibility conditions;

• Improved weather forecasting; • Redesign of runways and taxiways to avoid runway crossing.

It is apparent from the SESAR text that it was written with the full knowledge of the existence of

the CREDOS concept. “Reducing departure spacing by a better wake vortex management” is a

direct reference to the work being undertaken in the CREDOS project. There are other indirect

references to “reducing dependency on wake vortex separation” and in section 2.5.3.3 (Airport

Surface Movement) the need for air and ground-based WV prediction and detection is also

identified.

3.3 CREDOS Performance Expectations

Thus, at first view, it is clear that CREDOS is aligned with the SESAR target concept of

operations. What is less clear from a reading of D3 is the expected contribution of the CREDOS

research. Beyond the generic references to the need to increase runway throughput, there are no

specific indications of how (and how much) CREDOS is expected to contribute.

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As described in Section 2 (above), the CREDOS concept relies on the presence of wind to

remove the wake vortex of the preceding flight. Therefore it is conditional on the prevailing

meteorology. The benefit of applying CREDOS cannot therefore be guaranteed. Although over

time, based on the typical seasonal pattern of winds, an airport may feel able to increase its

declared departure capacity, it is unlikely in the shorter term that CREDOS will have any impact

on declared capacity. The benefit of CREDOS is to be considered more in terms of offering an

option to recover from incurred delay.

Nevertheless, the use of CREDOS does not need to be completely reactive. Provided that a

reliable wind forecast is available, ideally looking 20-40 minutes ahead, it will be possible to

derive the expected departure rate, and feed this into the planning process e.g. a DMAN, if in

use.

If CREDOS will not contribute directly through a declared increase in capacity, there are other

areas where it will bring benefit. Section 3 of D3 provides an assessment of the extent to which

the SESAR target concept will meet the performance requirements specified in D2. The Key

Performance Areas (KPA) are divided into three groups according to their visibility to the overall

system stakeholders.

Safety, security and environmental impact are considered to be the highest visibility KPA. The

potential benefit from an application of CREDOS are limited in these areas, although there should

be some environmental benefit from a reduction in departure queue time.

The SESAR concept recognises that even with all the benefits of its component elements

realised, there will still be periods of overload at the busiest airports. This will result in some delay

and queuing at peak periods. CREDOS could provide the mechanism to augment the departure

rate and so smooth out some of this delay effect. The extent to which CREDOS can fulfil this role

will depend on the actual wind required for CREDOS operations. If the threshold is relatively low,

and it is reasonable to expect that such conditions will coincide with these demand peaks, then

CREDOS will bring specific benefit.

The same applies to the KPA of predictability, efficiency and flexibility. The potential to

temporarily augment the departure rate increases the probability of on-time operations and so

reduces knock-on effects. One of the declared SESAR objectives is to have 98% of departures

leaving on time. Similarly in terms of flexibility, a temporary increase in departure capacity will

allow flights requesting a later departure slot for operational reasons, to be accommodated

without major disruption to the planning.

The CREDOS concept does not rely on the use of WV detection or prediction for operational use,

although some form of these two elements may well be required as part of a safety monitoring

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system. The CREDOS concept requires only the measurement and forecasting of the wind

conditions affecting the runway and initial climb phase.

Wake vortex detection and prediction have been used in determining the minimum wind

requirements and in providing the proof that the vortex is removed from the flight path. Thereafter

it is considered that for an operational use of CREDOS it will be necessary only to measure the

winds. The precision and accuracy of these wind measures will determine the size of the required

safety margins and thus the applicability rate of CREDOS. The SESAR target concept has

identified the provision and exchange of meteorological data as a key enabler for the construction

of the RBT. The availability of high performance meteorological sensors around the airfield, the

development of fine-mesh meteorological models, as well as the use of aircraft down-linked

weather data, will be very beneficial for CREDOS.

3.4 Conclusion

In broad terms, CREDOS is aligned with the SESAR target concept. Some clarifications should

be provided by the CREDOS consortium regarding the expected benefits of the CREDOS

concept to avoid misunderstanding of the benefits mechanisms. The benefits from CREDOS will

depend on the quality of meteorological data available. The CREDOS project is not working in

this area and so relies on this work being done elsewhere in the SESAR development.

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4 SESAR ATM Master Plan

4.1 Master Plan Overview

SESAR Deliverable D5, referred to as the Master Plan describes the high-level overview of the

work to be performed in SESAR. It is intended to be a rolling plan that will be updated periodically

as the work evolves. D5 contains the high-level view, the detail of which is described in a set of

lower-level deliverables, as well in the electronic plan being developed at www.atmmasterplan.eu.

Deliverable D5 was built on the previous SESAR deliverables, in particular D4, which described

the Deployment Sequence to be used to realise the SESAR Target Concept.

D5 has refined the D4 deployment sequence by splitting each of the three Implementation

Packages (IP) into two ATM Capability Levels (ACL) with associated ATM Service Levels (ASL).

This extra granularity was needed to better match the needs of the “rolling” Master Plan update

process. D5 proposes an initial set of dates for the lifecycle timing of all development activities. In

order to achieve agreed target dates for Initial Operational Capability (IOC) in Europe, the Master

Plan defines for each topic when R&D should start, by which target date it has to be completed,

and how much time is foreseen for initial implementation. These IOC dates have been chosen in

D4 based on the future performance needs of the most challenging operational environments in

Europe, and the maturity of the individual topics which will be subject to R&D and implementation.

The information used to establish these critical dates is based almost entirely on expert

judgement.

The main SESAR Implementation Packages are:

IP1 – (IOC date = 2013): linked with ATM Service Levels and ATM Capability Levels 0 & 1

IP2 – (IOC date = 2013-20): linked with ATM Service Levels and ATM Capability Levels 2 & 3

IP3 – (IOC date = 2020+): linked with ATM Service Levels and ATM Capability Levels 4 & 5

4.2 Lines of Change

Spanning these implementation packages, ten Lines of Change (LOC) have been defined,

covering the main operational areas that will evolve in the transition to the target concept.

For each of these lines of change the areas of development required for each ATM Service Level

and Capability Level have been defined in D5.

The list of LOC is given in Table 1 below.

Developments relating to CREDOS specifically and to wake vortex more generally are found

primarily in LOC#10 and to a lesser extent in LOC#8.

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LOC Title

1 Information Management

2 Moving from Airspace to Trajectory-based Operations

3 Collaborative Planning using the NOP

4 Managing the Network

5 Managing the Business Trajectory in real-time

6 Collaborative ground and airborne decision tools

7 Queue Management

8 New Separation Modes

9 Independent cooperative ground and airborne safety nets

10 Airport Throughput, Safety and Environment

Table 1: SESAR Lines of Change

4.3 CREDOS in the Master Plan

Given that the current CREDOS project will finish at the end of 2009, and that it is not itself an

implementation project, it seems unlikely that even the most basic implementation of CREDOS

could take place before the end of 2011.

This is consistent therefore with the description of CREDOS in ATM Service Level 1 (2009-2013):

Reduced Aircraft Separations.

“Introduce new procedures whereby under certain crosswind conditions it may not be necessary

to apply wake vortex minima.

Introduce fixed reduced separations based on wake vortex prediction.

[…] Constant time separations independent of crosswind conditions and wake vortex existence

are introduced.”

The first sentence clearly refers directly to the CREDOS concept. The other two sentences refer

to concepts such as the WIDAO concept (Paris) or the TBS concept (London) which have

benefited indirectly from the research performed in CREDOS.

CREDOS appears to be well aligned in the SESAR planning in terms of schedule.

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4.4 Meteorological Data

As described previously, CREDOS benefits are dependant on the quality of meteorological

service provision and this is also consistent with the SESAR planning for development. In the

same LOC for Service Level 1, SESAR plan to “Validate the use of weather information to

improve predictability and reliability of managing the traffic on the airport surface.”

Because the benefits of CREDOS are conditional on the presence of suitable winds, these could

only be translated into declared departure capacity if future systems were able to deliver a

weather forecast of sufficient accuracy to allow the CREDOS additional slots to be taken into

consideration. The potential to address this point is included in ATM Service Level 2 under

LOC#4 (Managing the Network) which describes the need to “develop facilities that support

Airspace Users in planning their 4D trajectories/missions (SBTs) through the NOP process while

taking into account airspace availability, other traffic operations, airport’s operational plans, Meteo

and the Users’ own exploitation plans. “. The importance of exchanging meteo data between air

and ground is also recognised in the SWIM development and is described in SWIM capability 1.

Likewise in ATM Capability 2, the uplink and downlink of meteo parameters is foreseen. However

there is no specific mention of the meteo parameters typically associated with wake turbulence

persistence.

4.5 Departure Managers

Basic DMAN functionality is foreseen as early as ATM Service Level 0, with more sophisticated

versions integrating pre-departure sequencing included in Service Level 1. The quantitative

benefits of CREDOS depend on the number of Heavy-Medium aircraft in the sequence (i.e.

where the suspension of WT separation minima would bring advantage). This constitutes a

possible input to a DMAN, which could, other priorities notwithstanding, construct an optimised

sequence for CREDOS operations.

If a wind forecast is available covering a period of at least 20 minutes, it could also be expected

that the CREDOS algorithm would provide the DMAN with estimates of the likely departure rate.

4.6 Conclusion

CREDOS is aligned with the Master Plan in terms of schedule. Links and dependencies of

CREDOS on meteorological data and departure managers may need to be more specifically

described.

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5 SESAR Work Programme 2008-13

5.1 Overview of the SESAR Work Programme

The SESAR Deliverable D6, entitled “Work Programme for 2008 -2013”, defines the collection of

all required project items in the 2008-2013 timeframe necessary to support the implementation of

the ATM Target Concept by the execution of the SESAR Master Plan. This includes deployment

of existing systems, development of systems, which are almost mature, applied research to refine

the concept and develop technical solutions and longer-term research for the more advanced

concept elements and technologies.

D6 in fact describes two plans:

• The Deployment Plan addresses all of the Operational Improvements (OI) identified by

SESAR Deliverable D4 as part of Implementation Package 1 (IP1). The basic

understanding is that these OI are at, or will soon reach, a state of maturity equivalent to

the EOCVM level V4 (industrialisation).

• The Network Development R&D Plan addresses primarily those developments needed to

bring the elements of Implementation Package 2 (IP2) up to the V4 maturity level in the

period 2013-2020. In this plan the activities related to airports have been split between

WP6 (Airport Operations) and WP12 (Airport Systems). More specifically wake

turbulence related activities are described in WP6.8.1 (Runway Management Operations)

and WP12.2.2 (Runway Management Systems). Activities related to meteorology have

been placed in WP15.4.9 (WP15 concerns CNS systems).

5.2 IP1 Operational Improvements relating to CREDOS

AO-0301: Crosswind Reduced Separations

AO-0303: Fixed Reduced Separations based on Wake Vortex Prediction

As well as these OI, there is also an OI Step which is focussed on the development of the basic

DMAN. TS-0201 is described as “The system determines the optimum runway for departure (if

appropriate) and the optimum order for the departure sequence taking into account departure

times, slot constraints, runway constraints such as departure rate, wake vortex separation,

distance in trail, etc.” ; yet there is no apparent linking of TS-0201 to the other OI addressing the

wake turbulence issue.

In addition to these there is the Procedural Improvement, PRO-066a (ATC Procedures to apply

new flexibility in application of wake vortex standards) which will address the short-term

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procedural aspects.

The position of CREDOS as an element of ATM Service Level 1 and the strong linkage with the

AO-0301, suggest that the continuation of work on CREDOS should be seen as part of the

Deployment Plan.

The distinction to be made between AO-0303 and AO-0301 is not clear. Both include the current

work of the CREDOS project. AO-0301 covers arrivals as well as departures; and AO-0303 keeps

a door open to look at other meteorological conditions.

However none of these aspects are considered to be at the V4 maturity level. The internal

assessment of CREDOS by the validation team is between V2 and V3, and that is limited to the

case of crosswind departures only.

5.3 IP2 Operational Improvements relating to CREDOS

AO-0304: Dynamic Adjustment of Separations based on Real-Time Detection of Wake Vortex

As for IP1, Procedural Improvement are also foreseen, this time affecting both ATC (PRO-144)

and the cockpit (PRO-AC-64).

Although AO-0304 seems the most likely place for a continuation of CREDOS R&D in IP2, the

inclusion of “real-time detection” in the title needs to be clarified. CREDOS does not see a role for

real-time WV detection except as part of a safety monitoring system.

Real-time detection may become a key element of the self-separation paradigm foreseen in IP3

but even there it seems more efficient to use mathematical models fed by high-resolution

meteorological data.

5.4 IP3 Operational Improvements relating to CREDOS

AUO-0504: Self-Adjustment of Spacing Depending on Wake Vortices

IS-0406 : Aircraft Dissemination of Information on Weather Hazards to Other Aircraft

IP3 represents a marked shift away from ATC separations toward self separation. Thus the link to

CREDOS becomes tenuous. However such a system will still need to address the departure

situation and so should link to the results of the CREDOS R&D.

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5.5 Treatment of the Wake Turbulence issue in SESAR

There are several other OI defined in SESAR which consider the wake turbulence problem. The

need to develop associate operational procedures is clearly described, as well as the need to

improvements in weather and WV detection and prediction.

The precise role of detection and prediction is not yet known. Given the very high cost of

detection compared to prediction; and given the high cost of airborne detection compared to

ground-based detection; it is important to establish the roles of these elements as early as

possible.

The table below summarises potential roles of prediction and detection based on the current

research.

Type Description Example Mechanism

Fixed Removal of a WT constraint based

on measures of WV behaviour

under all conditions

WIDAO

(CDG)

No operational use of prediction

or detection.

Conditional Suspension of WT constraints

under certain calculated conditions

CREDOS Prediction of the meteorological

conditions only.

Predictive Adjust WT separations based on

predicted behaviour of WV

ATC-

Wake

Use WV and meteorological

models to select separation

mode.

Reactive Onboard or ground-based detection

and avoidance of WV

TCAS

extension

Real-time WV detection

Fused

sources

Onboard or ground-based

adjustment of WT separations

based on fusion of detected and

predicted WV behaviour

SESAR? Use detectors to train prediction

models.

Use prediction to direct

detectors

CREDOS will provide a first indication of what can be achieved using only wind measurement for

operations. A local safety case of a CREDOS implementation would test whether this level of

information is sufficient.

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6 Summary of Conclusions and Recommendations

There is good alignment of the CREDOS project activities with the planned work of the SESAR

programme. The development of the SESAR Work Programme and all supporting documents has

clearly been done with full knowledge of the existence of the CREDOS project.

The main link of CREDOS into SESAR will be through the Operational Improvements AO-0301

and AO-0303. More general research on the use of conditional suspension of WT separations will

also be included in WP6 of the ATM Network R&D Programme. The scheduling of further

CREDOS work in the time-frame of IP1 seems appropriate. Nevertheless, the expectation of a

maturity level of V4 for inclusion in IP1 is not yet met by the CREDOS project.

There are some points of detail in the SESAR documents which may indicate a lack of

understanding of the ambitions and constraints of the CREDOS project. These should be

clarified.

• Capacity benefits delivered by the CREDOS concept will always be conditional on

suitable wind conditions. Thus, CREDOS should be seen only as a option for ATC to

apply to temporarily augment the departure rate.

• CREDOS performance will be increased by the availability of high quality meteorological

nowcast data. Meteorological developments are foreseen within the SESAR workplan,

but the specific link to crosswind reduced separations is not made. Weather service

enhancements are not considered within the CREDOS project.

• CREDOS benefits will increase if the departure sequence is optimised with regard to

Heavy-Medium pairs. This requirement should be considered in the development of the

DMAN functionality. Development of DMAN is not considered in the CREDOS project.

The wording of the OI related to CREDOS is not precise or detailed enough to determine the

scope of the work they describe. There seems to be overlap between AO-0301 and AO-0303. If

the scope of the IP1 activities is not made clear there is a risk that the work defined in WP6.8.1

for IP2 will not have the required scope.

The long-term scenario for managing wake turbulence is not yet clear. Various options exist, in

particular concerning the role of ground-based detection, airborne detection and prediction

models. Although it is useful to keep as many options open as possible at this early stage of

development, it is important to plan already the decision points which will lead to the final choice.

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page 21 of 21

The findings are summarised in the table below. The associated recommendations have neither

responsible person nor target date. The CREDOS project will endeavour to communicate where

appropriate with the task leaders of the SESAR development phase during 2009.

Ref. Issue Recommendation

1 Maturity level of the CREDOS concept is

considered as V2-V3 by the project team.

Confirm SESAR expectations of the

concept maturity

2 CREDOS will not increase declared departure

capacity

Confirm understanding of implications of

conditional suspension of WT

separations

3 CREDOS benefits will increase with

increasing quality of weather data

Ensure CREDOS requirements are

included in the SESAR meteorology

workpackages

4 CREDOS benefits will increase with the use of

DMAN

Use simulation studies to assess the

potential benefit.

Ensure that CREDOS requirements are

included in DMAN development work

5 Scope of SESAR IP1 work is not clear from

the text description provided.

Provide scope statements for all wake

turbulence activities in IP1 (AO-0301,

AO-0302, AO-0303).

6 Overall direction of WV R&D needs to be

refined, concerning the use of detection and

prediction in operational systems. There is a

risk of parallel development of redundant

systems.

Define decision points and, if possible,

decision criteria.