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Better Data Communications Make Greener Airlines
Rainer J Koll, Owner of Rainer J Koll Consulting and expert in Aviation Telecommunications looks at the way in which better data links and communications will result in greener airlines.
Aviation has understood the message to become more efficient and cleaner loud and clear. Much can be done by improving engine emissions and fuel efficiency. The latest Pratt & Whitney 10,000lb thrust aircraft engine is forecasted to cut fuel consumption by around 12% at its service entry in 2013. It will release much less nitrogen oxide & carbon monoxide and will be significantly quieter. Other manufacturers such as Rolls-Royce are set to achieve similar margins with their newest developments.
Several contributions
Although reducing emissions is an important part of the solution, no single measure will suffice to reach the required targets. Equally important are aims to enhancing aircraft operational efficiency so that any given amount of fuel goes a much longer way - and electronics will have to play a significant role in facilitating those efficiency gains. Aircraft electronics (Avionics) and aeronautical communication networks (Connectivity) tell pilots and ground crew about the state of the aircraft and improve situational awareness, leading to higher capacity and efficiency, providing a safe service with less disruption and reduced travel time. But technology alone, whether airborne or ground-based cannot create the necessary step changes. Air Traffic Management (ATM) infrastructures will need to be unleashed from their current procedural shackles that are often driven by outdated national soverenity interests, particularly in the crowed skies of Europe. A typical one-hour flight from London Heathrow to Cologne takes the aircraft through four different national airspaces, each endowed with a Flight Information Region (FIR) and its associated Air Traffic Control Centre.
747 Cockpit
All this is about to change since EURONTROL has lent its support to the Single European Sky ATM Research (SESAR) programme. SESAR is the European Air Traffic Management modernisation programme. It combines technological, economic and regulatory aspects and will use the Single European Sky (SES) legislation to implement the programme. The SESAR Consortium comprises of 29 companies with 21 associated partners:
- Airspace Users
- Air Navigation Service Providers
- Airports
- Supply Industry
- Safety Regulators
- EUROCONTROL
Taking a multi-pronged approach, it addresses technological, environmental and economic aspects of aircraft operations for 2020 and beyond. Efficient satellite and VHF-based data communication links combined with advanced avionics lie at the heart of the enabling solutions, realising collaborative planning, demand/capacity balancing of networked operations and 4D trajectory flight routing where basic airspace boundary management prevailed before. Satellite based air-ground data links will compliment existing VHF communications for new high capacity & high availability ATM messages services. Airline operations will see benefits through fuel efficient routes & flight profiles. New carbon efficient engine technologies together with remote engine diagnostics ensure that engines are kept at peak performance and any deterioration can be detected from the onset in flight and corrected at the next arrival. The emerging data link and messaging make use of:
- Environmental Data distribution, air-ground exchange of flight information
- Introduction of a sub-regional Air-Ground data link management sub-system
- Downlink of the aircraft flight path trajectory via satellite links and VHF
- Protected band “WiMAX” IEEE 802.16 for secure airport surface data link operations;
- Seamless network protocol to interconnect all nodes (e.g. IP).
Environmental benefits are expected to materialise as these technologies are implemented, particularly reduction in fuel burn due to optimisation of flight profiles resulting in reduction of gaseous emissions (CO2/Nox) and noise reduction and improved air quality. The carbon savings are estimated by the SESAR team at around 125 - 155 ktonnes of CO2 per annum. In fact, these savings are a strong driver for the airline industry to invest into the new technology. The other driver comes from the knowledge that with the anticipated increase in air-ground air traffic management communications and the emerging market demand for passenger communication services, current systems and technologies are expected to become saturated by 2020. The majority of Pilot to Controller communications today is voice based. To make better use of scarce capacity, SESAR compliant communications will rely more and more on data links. Nevertheless, current cockpit data protocols still conform to the X.25 ITU-T standard network layer protocol for packet switched data and the Air Transport industry faces a complex IP based network architecture evolution. IP-based networking solutions for air/ground communication will need to be deployed for cost savings, high reliability and an optimal alignment with the evolution of communication and security technologies.
Current and future aircraft communications
Civil aircraft today are fitted with two or three VHF radios for Air Traffic Control (ATC) and Airline Operational Control (AOC) in controlled airspace, two HF radio systems for oceanic and remote operations. Long haul, wide body aircraft such as the Boeing 747 and the Airbus A-340 are increasingly equipped with one or two Satellite Communication systems for oceanic and remote operational use and passenger communications, supported by one Gatelink radio system for short range data links at airports. Future regulation and market demand will add two L-band radios called L-band Digital Aeronautical Communications System (L-DACS) to augment the VHF systems, two new ATC Satcoms for Oceanic Air Traffic Management, replacing HF and WiMAX based radio systems for enhanced short range data links at airports (replacement for Gatelink). New Air to ground high bandwidth Ku-band passenger links are taking care of cabin connectivity requirements. - All are stand-alone systems with dedicated flight crew management panels or screens with little automated operation. Not surprisingly, pilot workload is a concern and higher levels of integration will become indispensable. Aeronautical standardisation and engineering committees are making good headway towards defining an onboard communications network that meets the need for integrated aircraft avionics architectures and that supports the future aeronautical air-ground data link communication requirements: At the beginning of 2008, the “Integrated Communications, Navigation and Surveillance Conference” assessed suitable system architectures and recommend system definition and avionics standardisation activities on the basis of the architecture shown in the diagram below. Insert
Connectivity Network Architecture
An EC funded 7th Framework Research project has been tasked with reducing the number of aircraft radios systems to a reconfigurable system that will fully integrate with the future Single European Sky ATM Research (SESAR) concepts, aiming for:
- Integration of a full range of applications and services
- Secure networks
- Effective firewalls between passenger and cockpit domain
- Network integration
- Unification of networking protocols
- Inter-working of different radio access technologies through a common IP-based aeronautical network
- Integration of radio technologies in an Integrated Modular Radio platform
- Hybrid Ku/L band Satcom antenna to develop an asymmetric high rate Data Link
The diagram below shows the system architecture concept envisioned by the EC research project.
Connectivity Layer 2 Architecture
Security and safety
However, the aviation community has also raised security concerns, insisting that the airborne network architecture consists of several securely segregated domains when using shared resources. Security must be designed into the network at multiple layers, into the network as a whole and into individual components. There are different security aspects and risks for each domain (risk-based security approach):
- Aircraft Control -> flight safety, availability, confidentiality
- Airline Operations -> integrity, confidentiality
- Passenger/Cabin -> confidentiality
A security failure of the avionics could result in exposure of confidential data, compromise the integrity of the data, or affect the availability of the data. Attacks could come from the Passenger/Cabin domain in an attempt to reach the cockpit. Security controls or functions of the modems, the server(s) and its Ethernet interfaces should therefore be resistant to such failures, yet the OSI Model layer 2 (Media Access Control layer) typically implemented as Ethernet, has no inherent security. Once an hacker has direct access to layer two, full compromise of the system is possible. Security controls must therefore be implemented at higher layers as well as in the physical environment. This means that the Ethernet interface should allow authenticated and encrypted connections when needed for the different domains and that steps should be taken to ensure that malicious cabin network activities cannot interfere with higher security domains. Insert altimeter image
Significant returns
Provided all planned Single European Sky ATM Research (SESAR) programme phases will be implemented, the operational efficiency gains and aviation carbon footprint reduction will be very significant indeed by the year 2020. European airspace en-route capacity is expected to increase by 31-40% and Flight inefficiency reduced by 25% (i.e. by more than 2 km/flight/year). Delays are set to reduce by 1.2 minutes/flight while traffic may increase up to 15.8 Million flights/year. Emissions are expected to reduce through approx. 3% fuel saving, leading to 125-155 Ktonnes per year less CO2 and removing up to 44% ground emissions at a typical hub airport. The associated cost savings are estimated at €0.7 - 1.1Bn/year for scheduled airlines. By 2020, the direct ATM cost is forecasted to be reduced from €800 to €630 per flight, and 50% ATM cost per flight reduction thereafter. Most of these savings can be achieved by more efficient ATM, targeting 98% of flights to depart on time and under 5% of flights to be less than 3 minutes delayed at arrival. More effective en-route airspace management based on flight path Trajectory Management and Automation will permit reduction of aircraft separation. This is the distance aircraft have to be kept apart to compensate actual heading and altitude inaccuracies. Future en-route clearances will be issued as initially 3D and later 4D Precision Trajectory Clearances, exploiting data links and trajectory exchange capability with the resulting navigation precision. This will allow the delegation of separation responsibility from ATM to the pilot for a specific situation: the controller detects situation - flight crew executes resolution. Insert Runway Ahead However, flight crews need to be equally supported to benefit from the technologies. The cockpit avionics will be adapted to reduce pilot workload whilst offering enhanced capabilities. Synthetic Vision Systems will provide flight crew with synthetic/graphical view, using terrain imagery and position/altitude on Head Up Display (HUD) technology to facilitate approach and ground operations in low visibility. Remote Tower Operations will exploit remote sensors in real-time, enhancing safety of oeprations in a cost effective way.
Rainer Koll is Managing Director of Rainer J. Koll Consulting Ltd (www.rjk-consulting.co.uk) and he specialises in Aerospace and Telecom. Rainer is a Fellow of the Royal Aeronautical Society and has managed large avionics businesses and major technology development programmes.