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SOLUTIONS WHITHIN THE SUPER HIGHWAY PROJECT

ALLOWING INTEGRATED USE OF AIRSPACE OF BOTH, CIVIL

AND MILITARY USERS

Amaya Prieto

ISDEFE, C/ Edison 4, 28006, Madrid, Spain

The Single European Sky (SES) [1] initiative showed the EU concern about optimising the airspace structure in order to fit the growing traffic demand and to increase the overall efficiency of the air traffic management system reducing fragmentation between states and Civil and Military Systems. The SUPER HIGHWAY [2] project aspires to augment en-route ATM capacity by organising traffic flows under a new structure based on non-conventional routes and to develop the operational procedures needed for managing this structure efficiently and safely, taking into account interests from both: national defence forces and civil aviation requirements. In order fulfil the civil / military harmonised use of airspace, two different functional solutions have been proposed within the SPH framework [3] for the implementation of the Flexible Use of Airspace [4] in the two scenarios studied: • The first Scenario, which structural design is defined by a volume that joins

together sets of parallel lanes (see Figure 2), does not require major efforts for implementation as long as it is settled within the current airspace and route structures

• The second Scenario, developed by the EEC, is formed by a layered route

network (regular lattice) that covers the whole Europe avoiding crossing traffic conflicts (see Figure 3). The challenge would be to find a gradual implementation strategy.

As long as the two scenarios presuppose the continuity of the structure defined all over Europe, and according to the SES initiative to reduce the fragmentation of European ATM systems, the Super Highways will not be constraint to national borders.

I. Introduction The purpose of this article is to describe, at a functional level, the application of the Flexible Use of Airspace to the Super Highway Concept. Operational experts should be able to evaluate, once the validation exercises are performed, whether any of the scenarios proposed meet the goals of a safe, efficient, seamless and harmonised air transport system that reduces the fragmentation of the European aviation. The exercises will show whether the high-level requirements provided are or not satisfied by the two design options described in the two scenarios. This paper will clarify the influences of Flexible Use of Airspace Concept issued in the SPH project.

7th AIAA Aviation Technology, Integration and Operations Conference (ATIO)<BR> 2nd Centre of E18 - 20 September 2007, Belfast, Northern Ireland

AIAA 2007-7876

Copyright © 2007 by Copyright © 2007 - All rights reserved to SUPER HIGHWAY project partners. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

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The operational requirements derived from the FUA can be classified as follows: For pre-tactical airspace management:

• ATCFM (Air Traffic Flow Capacity Management).

For tactical civil/military co-ordination:

• Civil / military data exchange. • Support to airspace crossings (N/A in Scenario 02).

II. Background The objective of the SPH project is to develop an innovative airspace traffic structure based on the simplification of the route network around the major European traffic flows.

The project expects to identify a new way of restructuring the current airspace that fits within the framework defined by the SESAR operational concept. The simulations are now being carried out and, according to the results achieved, they will show the feasibility and acceptability of the Super Highways. The targets of the validation are summarized in the following table [5] that includes requirements from SESAR (modernisation programme of Air Traffic Management System for 2020 and beyond) relative to today’s performance.

KPA Supporting Metric High level objective

target

Capacity

Taskload 1

Decrease taskload between a 20% and a 40%2 [6]

Workload3 per ATCo Workload per a/c

Reduce ATCo workload between a 10% and a 20% [6]

Nº of movements

Nº of flights traversing volume of interest

Increase nº of movements by a factor of 3 referred to current nº of movements [7], [8]

Safety Nº of conflicts

(provided an specific density of traffic)

Nº of potential conflicts (precursors of safety)

Nº of conflicts occurring within volume of interest (as a function of number of flights)

Increase safety by a factor of 10 [7], [8]

Efficiency

1 It is operationally accepted that when referring to taskload, only factors that do not depend on subjective ratings are mentioned. These factors are:

• Movements: number of aircraft in sector per hour, time aircraft spend in sector • Conflicts: number and quality of potential conflicts • Co-ordination: quality and effort of co-ordination events • Level change: workload effort for level changes.

2 It is assumed that a taskload decrease leads to a workload decrease for the controller. This is a reasonable assumption because a strong reduction of the tasks (quantitatively and qualitatively) reduces stress and strain from the controller thus reducing his/her perceived and actual workload. 3 Events are subdivided in tasks and several actions conform the different tasks using cognitive channels. Workload concept is based on:

• Events • Tasks • Actions

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Flight Efficiency: Delay of a/c per flight time, Delay of a/c

1 minute en-route delay per flight [6]

Any flight time increase greater than 1% will not be considered acceptable [9]

Flight Efficiency

Fuel efficiency: Fuel burnt per unit of distance (between volume entry and exit point)

Distance (and / or time) flown at the requested FL

Reduce environmental impact by a factor of minus 10% [7], [8]

ATM Efficiency ATM efficiency of the airspace design / procedures: Nº of coordination events per Nº of ATCo

Nº of flights per unit ATC taskload

ATM unit costs shall be reduced by a factor of 2 [7], [8]

Environment

Delay of a/c

Flying time

Flying distance

Fuel consumption

Fuel efficiency – fuel burnt per unit distance (between volume entry and exit point)

Reduce environmental impact by a factor of minus 10% [7], [8]

For a correct understanding of this paper, definitions and concepts deemed necessary for the contextualization of the solutions proposed concerning the dual use of the airspace will be described in the following paragraphs:

Airspace Management

Airspace Management is one of the three components of Air Traffic Management (together with Air Traffic Services and Air Traffic Flow Management). It covers the management of the environment in which the traffic is moving: the permanent and conditional routes, the temporary segregated areas, the danger, prohibited and restricted areas, etc. At the present moment, airspace is reserved on a quasi-permanent basis to ensure its availability whenever it is required. Inflexible airspace structures and reservations have resulted inefficient. The need for improved Airspace Management in Europe was recognised in the late 1980s when the continuing growth of aircraft movements exceeded the capacity of the Air Traffic Services Systems causing serious delays.

The Concept of Flexible Use of Airspace

The basis for the Concept of the Flexible Use of Airspace is that airspace should no longer be designated as either military or civil airspace, but should be considered as one continuum. Consequently, any necessary airspace segregation should be only of temporary nature. The FUA Concept is based on three Levels of ASM (Airspace Management) which have been identified the Airspace Management Handbook [10] as: • Strategic ASM - ASM Level 1 - Establishment of national airspace policy structures, • Pre-Tactical ASM - ASM Level 2 - Day-to-day allocation of airspace and • Tactical ASM - ASM Level 3 - Real-time use of airspace. The FUA Concept will allow a maximum joint use of airspace by appropriate tactical civil/military co-ordination at ASM Level 3.

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The application of the FUA Concept will also ensure, through the daily allocation at ASM Level 2 of flexible airspace structures (conditional routes, temporary segregated areas), that any necessary segregation of airspace is based on real usage within a specific time period.

Military Requirements

Military air forces are essential for the security and defence of the countries. Therefore, it is a fundamental requirement that each state is able to train and operate its military forces. They need sufficient airspace available and opportunities for military training. The military objectives are based on the document “Future Military Airspace Requirements” [4]. Both scenarios focus on the listed objectives that are derived from a meeting with the European Commission and the Military Directorate of Eurocontrol [11]: • The Flexible Use of Airspace (FUA) is addressed. • Regarding the Functional Blocks of Airspace (FAB), the scenario describes how the civil-

military coordination will be done. The use of the FAB should ensure access “anytime” “any where” to the military.

• How does the SPH address the military requests for the use of dynamic airspace? This includes the dimension of the military reserved areas.

• How will military aircraft join the Super-Highway? • Efficient, flexible and safe management of airspace for both civil and military users are

critical for the Eurocontrol aim of improving of European ATM. These descriptions are complemented by behavioural and performance specifications, safety and flexibility requirements.

Route adaptation to military requirements

The airspace utilisation has to be optimised to satisfy military and civil needs. This can only be achieved with a new flexible approach towards airspace design and airspace management, which requires airspace planners to be aware of the operational needs of all airspace users. Some of the military needs are: • To accomplish their missions, military aircraft must be able to operate without restrictions in

all classes of airspace at all the times required in accordance with their assigned tasking. In many cases, military activities must be separated from other air traffic in segregated airspace.

• Besides the dimension of airspace for military use the distance from the airbases to the Temporary Reserved Airspace (TRA) / Temporary Segregated Areas (TSA) must be short enough to ensure an economic ratio between transit and training time.

• The TSAs / TRAs used for air combat manoeuvring should generally be under radar coverage of military air defence units.

• The design of TSAs /TRAs must reflect the regional/national composition and task of forces and may have to be adjusted whenever new aircraft and weapons are introduced.

• Some TSA/TRA or portions cannot be crossed by civil traffic while other portions do allow the coexistence of OAT (Operational Air Traffic) and GAT (General Air Traffic) in the same area and at the same time and will thus permit as much as possible the continuation of civil air traffic flows. This is shown below:

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Figure 1: Military Airspace Utilisation [4]

In order to maintain the operational readiness in a cost-effective manner, the future military airspace requirements will be met by providing sufficient airspace based on the following principles defined in the EUROCONTROL Airspace Strategy for the ECAC States: • Freedom to operate at any time in all areas of ECAC airspace; • Special handling in particular for priority flights and for time-critical missions, but also for

military aircraft whose equipment is not fully up to civil standards; • Possibility of conducting uncontrolled VFR flights, including in managed airspace (MAS)

retained; • Temporary airspace reservations (e.g. TSAs for low-level flying, in-flight refuelling, air

combat training, high-energy flying and other activities incompatible with the normal application of the rules of the air) as close as practicable to the respective airfield;

• Airspace restrictions for activities not related to aviation, like the protection of areas of national interest, air-to-ground firing ranges, air-to-air gunfire and missile firing areas etc;

• A more dynamic airspace allocation system with enhanced Flexible Use of Airspace (FUA) application.

Dynamic activation

The activation / deactivation must include the pre-tactical phase (aside from the strategic and tactical phases). Civil-military coordination regarding the Functional Blocks of Airspace (FAB) should ensure access “anytime” “any where” to the military. The use of airspace should be optimised dynamically according to the needs. Airspace Management Cells (AMC)

The civil airspace users will have to be coordinated with the jointly planned military airspace utilisation. This will be done by the Airspace Management Cells (AMC), whose responsibility lies on managing the airspace over the Super-Highway, conventional sectors and military airspace areas of utilisation according to the expected needs. The AMCs should increase their efforts to optimise the use of finite airspace resources through appropriate civil/military coordination. In principle, airspace should only be segregated for the periods during which actual utilization is intended.

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Emergency procedures

The diverse circumstances leading to each specific emergency situation will be resolved following the same procedures than today, in the conventional airspace structure.

III. The Super Highway proposal A Super-Highway is defined as the airspace structure located in high-density, high-complexity areas of traffic where air routes are already overloaded. The Super-Highway may have one or multiple parallel lanes depending on the specific traffic conditions and will be characterised by enhanced procedures describing the way to operate, enter and exit the Super-Highway, as well as how to cross lanes or other Super-Highways when needed. Assumptions of the Project: • The potential users are assumed to be similar to the users of today’s airspace complying

with SPH equipment requirements. • The activation and deactivation of Super-Highways is part of a future Air Traffic Flow and

Capacity Management (ATFCM) process. This process and the algorithms are not subject of the scenario description.

• The ATFCM unit, based on the flights having requested the use of a Super-Highway, should also be responsible for activating a certain number of lanes depending on the expected traffic.

• Route charges are not considered. Depending on the results of the benefit assessment different route charging fees will be analysed.

• The possible existence of Functional Airspace Blocks (FAB) for the future is not specifically addressed. However, it is envisaged that FAB’s are implemented. That eases the design, procedural and military operations of a Super-Highway due to the fact that the FAB structure, by definition, takes into account air traffic flows and ensures a fluent and flexible transfer of responsibility for air traffic control between air traffic service units.

• Handling of specific weather problems is not addressed. It is assumed that the procedures e.g. for circumventing thunderstorms are not different from current standard practises.

Scenario 01: The rectangle cross section solution allowing Integrated Use of

Airspace

Scenario 01 structural design is defined by the volume of a long prism with a rectangular cross section gathering traffic operating between city pairs. Figure 2 shows the shape described in this first scenario. The prism contains several parallel lanes and FL. Each SH comprises two compact blocks, one for each one of the two complementary ways. Each block contains a certain number of lanes in each direction, with no empty flight levels left, but with restricted height, in order to allow transversal traffic to fly below or over in the conventional routes crossing the SH. All the lanes of the SH will be located in the upper airspace, between Flight Level (FL) 290 and 390, so that meteorological influence can be avoided as much as possible.

The number and position of the lanes and FLs active will be specified during the strategic phase, once the traffic demand is known by the ATFCM.

The rest of the FLs will be available for adjacent traffic.

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Figure 2: SPH Scenario 01

This rectangular cross section prism will be inserted within conventional sectorisation of the surrounding airspace. It will be operated by special controllers in same ACC than conventional sectors, even though the SH Control Units will probably be different due to their different needs. The limits of the sectors, dependent on flows and unconstrained to national borders, will not be located in the neighbourhood of major conflict points, in order to prevent the need for excessive coordination between controllers. In addition, sector dimensions should be designed to accommodate air traffic control functions and procedures. There must be a limited number of SH arrangements, and all the possible established configurations would be published in the Aeronautical Information Publications, by the appropriate ATS authority so that all the stakeholders, including the Armed Forces, will have a common and complete perspective of the overall structure, providing quick adaptability of the Super-Highway to sudden changes. Configurations shall include lanes, FLs active and sectorisation.

The segregated use of airspace for civil and military will be as short as possible and only active during military operations. During that period, Super-Highway ´s structure will avoid any of its specific configurations intruding in the volumes of airspace for military use. Specific lanes in a sector would be opened as needed (based on traffic and military requests). This is how a harmonised air traffic management network can be established in Scenario 01 for augmenting civil-military coordination.

Scenario 02: The Regular Lattice solution allowing Integrated Use of Airspace

Scenario 02 describes a particular approach to the design of a network of highways in the European airspace. It is a pan-European approach to airspace design, which has the intentions of increasing safety and capacity. This may be achieved through the innovative design approach because it is composed of allocation of cruising traffic to layers of parallel tracks. Within a layer, aircraft may only fly in one direction or the opposite direction and, in this way, crossing conflicts

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between cruising aircraft are eliminated. Different layers allow different directions of flight. Parallel lanes can be added to the regular lattice in order to increase the physical capacity. The first design principle in which this Scenario is based is the network design with layers of Parallel Tracks [12] in which cruising traffic is allocated. The preferred scheme uses a stack of four layers, each with two allowed directions of flights. There is a 45° degree difference in angle between the tracks in one layer and those in an adjacent layer. The stack of four layers may be repeated. This scheme results in flown distances that are comparable with conventional routes (i.e. 5% - 6% greater than the direct distance on average, with a maximum of 8.6%) and allows aircraft to cruise close to the requested flight level (on average 1000 feet away from the RFL, worst case 2000 feet away).

Figure 3: SPH Scenario 02: Layers of parallel tracks

To navigate between two points, e.g. from top of climb to top of descent, an aircraft first flies in one allowed direction at the associated flight level and then turns 45° and climbs or descends 1000 feet to fly in a second direction.

Figure 4: Following two allowed directions to reach a destination

The second design principle is to choose track spacing such that the tracks form a regular lattice.

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Figure 5: Regular Lattice

If airspace has a regular structure, then its operation should be essentially the same throughout the region in which it is applied allowing the interoperability requested by the Single European Sky [1] initiative. A key parameter in the definition of a lattice is the lattice spacing. This parameter effectively determines the density of routes in the lattice. The lattice spacing can be derived from the minimum crossing-free distance, which is the minimum of the greatest distance that can be flown in any of the allowed directions without crossing another track. This is effectively the minimum distance within which vertical manoeuvres can be executed without meeting crossing traffic. One application of this second scenario is the sparse lattice shown in Figure 6, in which each route consists of a pair of lanes, with one lane in each direction.

Figure 6: Sparse Lattice with a pair of lanes applied in European airspace

To increase the number of routes and total lattice route length (physical capacity) the lattice shall have as small lattice spacing as possible. Such a lattice is termed a “dense” lattice, like the one in Figure 7.

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Figure 7: Dense lattice applied in European airspace

On the other hand, aircraft using the lattice should, ideally, be able to climb into the lattice and, if necessary change level within the lattice, without encountering crossing traffic, i.e. they should be able to execute these vertical manoeuvres within a distance equal (or closely related) to the lattice spacing. If an aircraft cannot perform these operations it would effectively be unable to enter the lattice. There should, therefore, be an intermediate lattice spacing according to the traffic demand and the aircraft performances. The solution that this scenario brings in, regarding the FUA requirements, is the choice of selecting those routes avoiding the airspace temporary reserved for military users, as long as there many possible routes through the lattice between two points. In general, two points (such as top of climb and top of descent points) define a parallelogram of possible routes all of which have similar lengths (in a flat plane they are have the same length).

Figure 8: Alternative routes

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Flow management can take advantage of this multiplicity of similar routes to allocate routes to flights such that sector capacity is not exceeded. If greater increases in the distance flown are allowed, then more routes through the lattice become available. Similarly, flights can be re-routed around active reserved areas. Ideally reserved areas should fit within “holes” in the lattice. Alternatively, it may be possible to deform the lattice around a reserved area as shown below:

Figure 9: Reserved areas

The usability of these areas depends upon their shape and size.

IV. References [1]Single European Sky, 2004 http://ec.europa.eu/transport/air_portal/traffic_management/materials/doc/2004_single_european_sky_presentation_en.pdf [2]SUPER HIGHWAY Project (SPH), 2006 http://www.sh.isdefe.es ATM research project, funded by the Directorate General for Energy and Transport in the 6th Framework Programme, investigating ways of how operating major routes and lanes in Europe in accordance with the Airspace regulation (EC) No 551/2004 [13] [3]SUPER HIGHWAY Consortium, D1.3 Operational Concept Scenarios, SPH-WP1-DFS-031-V0.4-ED-PU, February 2007 [4]Civil / Military Interface Standing Committee, Determining Future Military Airspace Requirements In Europe, April 2003

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[5]SUPER HIGHWAY Consortium, D2.1 Validation Strategy And Planning, SPH-WP2-ISD-030-V0.2-ED-PU, January 2007 [6]SUPER HIGHWAY Consortium, D1.1 Objectives and Requirements, SPH-WP1-DFS-016-V1.0-ED-PU, December 2006 [7]SESAR Consortium, Air Transport Framework The Current Situation, SESAR Definition Phase Milestone Deliverable 1, DLM-0602-001-03, July 2006 [8]SESAR Consortium, Air Transport Framework The Performance Target, SESAR Definition Phase Milestone Deliverable 2, DLM-0607-001-00, December 2006 [9]SUPER HIGHWAY Consortium, Minutes from Meeting with Iberia, WP0-ISD-038-0.2-MM-CO MEETING, November 2006 [10]The MITRE Corporation, The Airspace Management Handbook V2.2, December 2005 [11]SUPER HIGHWAY Consortium, Minutes from EC-Meeting in Brussels, Operational Concept Scenario Discussions with EC, SPH-WP1-ISD-030-0.1-MM-CO, October 2006 [12]Eurocontrol Experimental Centre, Bretigny, and Layer of Parallel Tracks: A speculative approach to the prevention of crossing conflicts between cruising aircraft, 2004 [13]European Commission, Regulation (EC) No 551/2004 of the European Parliament and of the Council of 10 March 2004 on the organisation and use of the airspace in the single European sky (the airspace Regulation), March 2004

V. Keywords

Airspace Optimisation, Super Highway, Air Traffic Management, Civil-Military Coordination

VI. Author’s Biography

Amaya Prieto got her M.Sc in Physics in the University of Zaragoza, Spain. Then she started working on Air Traffic Management Systems for two years as a Technical Assistant to Aena (Spanish Airports and Air Navigation), in the “Flight Data Processing” and “Surveillance and Radar Data Processing” Departments of the Automation Division in the Automated Air Traffic Control System (SACTA) as a Systems Engineer, specifying requirements, discussing proposals of changes of engineering (PCIs), performing tests of validation of SACTA at the Experimentation and Development Centre, implementing the System in national Traffic Control Centres, and giving support to the validation of the controllers. After that, she became a specialist in Satellite Communications, giving Technical Assistance to the Spanish MoD (Joint Staff) working for one year in INSA. In 2006 she joined the International Transport Research Project department of Isdefe. Her duties there have been focused on Air Traffic Management research projects funded by the European Commission (EPISODE 3, SUPER HIGHWAY). She has developed activities in the fields of validation and operational concept definitions.