Overview

Events

Airspace Organisation & Management

Capacity Enhancement

Navigation

Interactive Applications

Acronyms

EUROCONTROL > ATM Performance > EATM > Airspace > Navigation

Navigation Domain

Overview

The growth in air traffic in the ECAC area is placing increased demands on the need to enhance the organisation and use of the European ATM network. Additional capacity will need to be delivered, flight efficiency improved and environmental impact reduced, while maintaining or improving safety of operations. Navigation developments will form an important part of the developments in the next 10-20 years.

Air traffic diversity is expected to become more complex with the emergence of Very Light Jets (VLJs), Unmanned Aerial Systems (UAS) and the multi-task nature of military aerial missions. This will alter the aircraft performance mix of the airspace users and lead to additional diversity in the airspace user capability. The capability of the navigation system carried by this diverse user mix will also vary. At the high-end, equipment capable of providing three dimensional (3D) and some initial four dimensional (4D) control will become available in the 2015 period. Ultimately, greater 4D control will lead to the ability to undertake a fully integrated air-ground ATM in line with the SESAR concepts of business trajectories. At the same time, however, older generation aircraft included in the mix will have FMS/RNAV equipment having a more limited capability. State aircraft also need to be assured of access to airspace in cases where because of physical or mission constraints; they cannot provide the navigation capabilities available on the latest civil aircraft.

This mix of navigation capabilities presents a challenge in providing improved ATM efficiency using the technological progress of the more advanced systems and catering for the lower capability aircraft. Faced with these realities, the ECAC airspace will seek to maintain or improve safety levels while becoming more flexible and adaptable. At the same time, an effective balance between capacity, mission effectiveness, flight efficiency and environmental requirements will be sought whilst managing the ATM structure containing aircraft of mixed navigation capability. The role to be played by improved Navigation Applications, supported by a cost effective NAVAID Infrastructure, is vital to meeting these challenges.

Navigation Requirements

Both the 2015 Airspace Concept and Strategy and the SESAR Concept of Operations address the above issues by proposing ATM changes that demand significant changes to existing navigation capability. This capability has been developed over a number of decades: ECAC has introduced RNAV operation en-route and in the TMA which has enabled significant operational benefits to be achieved. Each step has required the definition of new navigation functionality and its implementation onto the ECAC fleet. The interval between the definition of initial navigation functional requirements and their wide-spread use within the fleet can exceed 20 years. This demands that there be sufficient vision of expected future requirements and means of meeting these requirements that allow the required planning to be undertaken.

The evolution of Navigation in ECAC area is derived from the need to support future operations in the context of the Airspace Strategy. The strategy addresses both navigation application and the positioning infrastructure needs to support the navigation applications.

Navigation Strategy

The Strategy identifies the general principles and actions necessary to provide a harmonised and integrated framework for the future air navigation environment for the entire ECAC airspace in the period from 2008 to 2020+. It addresses the navigation applications meeting the requirements for the Airspace Concepts to the period to 2020+.

Up to 2011, airspace developments in ECAC are included within the DMEAN Framework Programme. With effect from 2020+, the SESAR ATM Target Concept (D3) is intended for application. In terms of both airspace and navigation, a striking conceptual evolution is envisaged between the 2008-11 timescale and the concept set out by SESAR for the 2020+ time frame. Given the considerable differences between the envisaged operating environments of DMEAN and SESAR, it is inappropriate to consider this change can be implemented in a single step. On the other hand requiring stakeholders to re-equip for several small steps will involve significant costs. Therefore a single intermediate step towards SESAR at 2015 has been developed and endorsed. This is set out in The 2015 Airspace Concept and Strategy for the ECAC Area, which provides a target for airspace developments. This concept provides a means of meeting the challenging 35% traffic increase forecast up to 2015 compared to 2007 and the commensurate environmental and flight efficiency demands.

The Navigation Strategy addresses these requirements addressing all phases of flight addressing the provision of the navigation capability meeting the operational requirements of both the SESAR ATM Target Concept and the intermediate 2015 Airspace concept. The strategy also addresses ICAO’s Performance Based Navigation Strategy as agreed at the 36th ICAO Assembly in September 2007. It describes available and potential air navigation applications and the means of supporting these applications, in terms of required performance, equipment functionality, and enabling infrastructure. In identifying the Navigation Infrastructure, the strategy takes due account of the ICAO Global CNS Concept and the EUROCONTROL GNSS Policy.

Strategic Streams

The Navigation developments strategy identifies 4 strategic streams, the first three streams lead streams concern the navigation applications for En-route, Terminal Airspace and Approach Operations and the fourth, addresses the infrastructure requirements.

Stream 1: En-route Navigation Applications

The B-RNAV (termed RNAV 5 in the ICAO Performance Based Navigation Manual) mandate of 1998 enabled a significant improvement in en-route airspace capacity by allowing new routes to be provided at bottlenecks in the ECAC route structure.

It is expected that some states will introduce P-RNAV en-route to support more closely spaced routes prior to the move to the post 2015 requirements. P-RNAV is closely aligned to the RNAV 1 requirements as set out in the ICAO Performance Based Navigation Manual.

The requirements set out in The 2015 Airspace Concept and Strategy for the ECAC Area will demand greater functionality and quality of service than can be offered by P-RNAV. To meet this requirement, RNP equipment will be needed to provide the additional functionality. As part of this concept, the judicious application of the Required Time of Arrival Functionality of modern FMS will provide a valuable step towards the 4D Navigation capability required by SESAR in the 2020+ timescale.

Stream 2: Terminal Navigation Applications

Unlike en-route operations, there is presently no ECAC wide requirement for RNAV operations in Terminal Airspace. However, where RNAV applications are needed, Precision RNAV (P-RNAV) provides the functionality needed for terminal operations. P-RNAV is increasingly employed in ECAC but for the 2015 period the “2015 Airspace Concept and Strategy for the ECAC Area” will require the application of the capability of RNP equipment which, as for en-route operations, will provide a valuable step towards the Navigation capability required by SESAR in the 2020+ timescale.

Stream 3: Approach and Landing Navigation Applications

This stream consists of two parts:

The first based upon operations using RNP equipment termed RNP APCH. For the more demanding operations RNP AR APCH where AR stands for “Authorisation Required”. RNP AR APRCH is designed for situation where the environment (for example operation in terrain rich environment) necessitates additional operational means to ensure the required performance is achieved. For these operations Barometric vertical guidance will be available.
LPV operations using SBAS/GNSS will provide vertical guidance using the SBAS signal. These approaches will provide improved accessibility and safety of operations airports where today only non precision approaches are available. They can also provide a backup to ILS when this is out of operation.
The second part of stream 3 addresses Precision Approach. It has been identified that the continued availability of ILS for as long as it is operationally and technically possible, is the most cost efficient way to ensure the provision of low visibility procedures. Even for a system as mature as ILS there are ways in which its operation can be improved and these are addressed in the strategy. Where operational constraints to ILS necessitate a move to an alternative system, MLS is at present the only alternative to ILS CAT II/III. A GNSS Landing System (GLS) based upon GBAS with GPS only will provide Cat I operations in the period from 2009 and it is expected that GLS Cat III using GBAS/GPS together with on-board augmentations will be available by 2013. The long term aim being to make use of multiple satellite constellations when Galileo is available with dual frequency to enable GLS Cat II/III without the need for on-board augmentation.

Stream 4: Evolution of Navigation Infrastructure

The strategy, in line with the ICAO Global CNS Concept, identifies a gradual increase in reliance on GNSS with its final goal being sole service to the extent that this can be shown to be safe and cost beneficial. From safety/security studies to date, the availability of dual constellations each transmitting on two frequencies is an important step towards this target. Nevertheless, GNSS signals are of extremely low power and small jamming devices are available which could prevent service over 100-200 N Miles. This, and the occurrence of solar storms which have jammed multiple satellite frequencies over many hundreds of miles for periods up to 20 minutes, necessitate the continued availability of terrestrial navigation aids at least in the period up to 2025+.

For RNAV operations in both En-route and Terminal Airspace, DME will provide the required backup. For landing, ILS will be retained throughout the period of the strategy. This will result in some of the VOR and NDB being in excess of what is needed for the network operations allowing Stakeholders to consider the potential for decommissioning.

As the ECAC wide operational requirement develops, the navigation accuracy and functional requirements will reach the stage where operations can only be supported by RNAV, the airborne equipage requirements for Area Navigation and Flight Management systems will need to increase beyond the level applied today where reversion to conventional navigation is possible. Once VOR and NDB are no longer capable of supporting reversionary operations, States will need to consider whether there is a local need for their retention or whether decommissioning is possible. The navigation strategy identifies this to be before 2015 for NDB and in the period 2020-25 for VOR.