Deepali Roy
Senior Assistant Editor
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With growing air traffic volumes, there is a lot of demand on air traffic management to manage the congestion on the runways and in the skies. Geospatial technology can help address this demand
Human ambition to fly is the stuff mythologies are made of. In modern times, ever since the Wright brothers took to the skies, there has been no looking back in advancements in aviation technology. Air travel is no longer confined to being the privilege of the elite that it once was. According to industry estimates, air traffic has doubled every 15 years since 1970. Having recovered from the economic recession, the aviation industry is bullish going ahead, fuelled by dynamic growth in emerging markets, increasing urbanisation driving wealth and traffic growth, strong continued growth in North American and European markets and expanding global middle class globally. Aerospace company Boeing's forecast for 2011 anticipates delivery of 33,500 new airplanes (including passenger and freighter) over the next 20 years, while Embraer projects that world air transport demand will grow by 5.2% per year during this period.
Clearly, there is a lot of demand on air traffic management to manage the congestion on the runways and in the skies.
Geospatial technology in air traffic management
Given the inherent spatial nature of the aeronautical data, geospatial technology can play an integral role in ensuring smooth and safe flight movements amidst growing traffic. Geospatial technology is one of the key enabling technologies being used in overall planning, deployment, delivery, maintenance, and management of the aviation infrastructure, says SV Satish, General Manager – Air Traffic Management, Airports Authority of India. It is changing the way the cockpit resource management and flight management are taking place in the modern aircraft fleet. Electronic flight bags are replacing paper charts and maps. Electronic route bulletins, aerodrome information, electronic aeronautical information publications, electronic terrain obstacle data are all the outcomes of geospatial technology.
Let's take a detailed look at the role of various geospatial technologies in air traffic management.
GIS
Aviation managers have critical requirements for reliable data and cost-effective workflows. Adding a spatial component to their data, GIS can help them model and track flight paths and analyse data for concerns such as noise levels and height clearances. Terry Bills, Transportation Industry Manager, Esri elaborates that commercial airlines and air traffic control regulators use GIS for airspace planning and routing applications as well as for facilities management applications. In addition, by managing data once and producing multiple products from aeronautical information management (AIM) system, aeronautical offices can realise an operational advantage. The database-driven geographic information system approach means that changes are reflected on all related products automatically through one-touch editing. This enables the organisations to create high quality data and charts in less time and with less money, informs Terry.
The civil aviation administrations of a number of countries are migrating to GIS technology to manage and update the aeronautical charts that are used by the pilots and air traffic control staff. Terry says that the major shift for many of these agencies is away from CAD produced maps to a data base driven and intelligent maps, which are increasingly replacing the paper charts that pilots used to carry.
GIS is also helping aviation authorities tackle old woes. One such woe is bird strikes. Aircrafts have battled bird strikes for decades. Airports are turning to technology to prevent the collisions between birds and planes. An instance can be seen in Australia where Adelaide airport is integrating GIS into its wildlife hazard management programme. The GIS brings together more than 20 years of bird census and bird strike data to generate interactive, real-time maps of bird congregation over the airport site. Adelaide Airport Limited (AAL) Environment Officer Renae Eden says once the authority enters the data in the GIS, it can produce real-time maps, which make it easier to model trending and examine where bird populations have moved over subsequent seasons. The bird mapping tool enables AAL to mitigate hazards before they can create an incident.
GNSS
Global navigation satellite system (GNSS), that provides accurate locations for cars, boats and aircrafts, has a lot of potential in air traffic management. The primary use of GNSS is for computing the aircraft position in order to navigate the aircraft, informs Richard Farnworth, Navigation Specialist, DSR/CMN/Navigation and CNS Research, Eurocontrol, the European organisation for the safety of air navigation. GNSS is also being used for surveillance applications where the position computed on the aircraft is sent to the air traffic control centre via data link, thus providing an alternative or a back-up to radar surveillance. GNSS is being used for instrument guidance during approaches to airports, adds Farnworth.
RNAV (area navigation), a method of Instrument Flight Rules (IFR) navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigating directly to and from the beacons, makes use of the flight management computer to allow navigation between any two waypoints, independent of the location of navigation aids. In 1998, basic RNAV became mandatory in European airspace and the only way for many aircraft operators to become RNAV capable was to be equipped with a GPS receiver. Farnworth says that the RNAV approach with precise lateral guidance has been made possible due to the widespread availability of GNSS on all categories of aircraft. This approach has been introduced in place of non-precision approach (NPA) as a means of improving pilot situational awareness and therefore safety. They can also be used in low visibility conditions over conventional NPA, allowing better access to airports in poor weather.
Satellite-based augmentation system
GNSS alone is not always sufficient or reliable to meet the stringent requirements of accuracy, integrity, availability and continuity for aviation safety of life applications, observes Satish who adds that the inherent limitations of standalone core constellations can be overcome by augmenting the core constellation signal in space. Farnworth informs that vertical navigation capability is enabled by either the integration of barometric vertical data by the flight management computer or through the use of a satellite-based augmentation system (SBAS). In the case of SBAS procedures, the minima can be as low as 200 ft which is equivalent to that achieved using a precision Instrument Landing system (ILS) Category I.
The most significant benefits of SBAS are in the approach phase of flight, giving performance as good as Cat-1 ILS without having to install any navigation infrastructure on the airfield, says Farnworth. This allows for high performance instrument approach procedures to be implemented at smaller aerodromes where it was previously uneconomical to install instrument landing systems.
While SBAS provides an improved navigation capability for some aviation users such as the general aviation community and those not equipped with modern avionics, Albert Tjoeng, Assistant Director, Corporate Communications, Asia Pacific, International Air Traffic Association (IATA), opines that the aircraft fleets of most commercial airlines have on-board avionics that already allow for accurate tracking without the use of ground based navigation aids. In addition, most of today's commercial aircraft fly to airports where ILS are installed. Albert cautions against the cost factor of SBAS. Albert says that SBAS offers no additional capacity over what airlines are currently able to do but has potential for a significant increase in costs to an already overburdened airline industry.
Remote sensing
Remote sensing can contribute in a number of ways in air traffic management. One significant application is addressing flight delays. Flight delays are a financial burden for airlines and a major inconvenience for the passengers. Even though there can be several reasons for flight delays, one of the reasons is congestion – too many aircrafts in too small an area, in the same time. Remote sensing can come to the rescue in such a situation. Stereo remote sensing can allow aircraft flight controllers to minimise such delays.
Dejan Damjanovic, Director, Air & Marine Solutions, GeoEye explains that aircraft congestion problem can be segregated into in-flight delays that involve flying from airport to airport, and ground delays that involve taxiing to and from the runway. Since an aircraft cannot be in the same 3D place at the same time as other aircraft, traffic congestion is a 4D problem. One of the new methods of air navigation that has evolved with technology advancements in navigation is known as required navigation performance (RNP,) which attempts to segregate airplanes by their ability to navigate in 4D airspace and allows airplanes that can support greater navigational accuracy to fly in smaller containment regions. If an aircraft can fly in a smaller 4D containment, it is possible to get more planes into and out of any given airport. To use optimised RNP routes in and out of airplanes requires 3D surveys of all obstacles that might be in the path of the new routes. This requires stereo remote sensing to support 3D feature extraction of the following: airport runways, taxiways, ramps and buildings to accurately map the airport and optimise taxiing routes; obstacles that may be tall enough to pose a hazard to aircraft taking off and landing on the new irregular RNPbased routes; terrain and other natural features like tree lines that may be tall enough to pose a hazard to aircraft taking off and landing on the new irregular RNP-based routes.
Satellite technology can also address weather-related issues. Moderate to severe weather formations often affect flight movements. Flights are normally equipped with weather radars and can request deviations away from weather. Similarly ground radars (primary radars) help in providing air traffic controller information on weather. But normally this information is restricted to 60 miles around major aerodromes, informs Satish. The advent of computer networking, coupled with geospatial technology and satellite weather forecasting helps in advance planning and control of air traffic. With the development of technology, specific weather patterns can be provided to aircraft on board for pilot to plan and manage routes that will have lesser impacts due to weather.
Current status of application
Airport traffic control systems often have numerous security and safety concerns to address in case of embarking on major changes, therefore technology adoptions usually take time. But changes can be seen in recent times. Bills says that in terms of the actual application of such systems, it has been rapidly adopted over the last five years. Nearly all of the North American and European international airports have implemented GIS and it is now spreading to Asia and the Middle East, as well as down to regional airports.
Looking ahead
As air traffic volume increases and aviation assumes importance in the global economy, airports are gearing up to handle the volume and improve efficiencies through next generation air traffic control systems that call for greater use of geospatial information and technology. For instance, one of the world's biggest and busiest aviation hubs, the United States has embarked on The Next Generation Air Transportation System (NextGen), the Federal Aviation Administration's on-going transformation of the national airspace system. NextGen supplants the radar and voice communications used today with satellitebased technologies and digital communications, according to FAA. Also, With the publication of Advisory Circular 150/5300-18B, the FAA has established a comprehensive digital data standard and roadmap forming the basis of what is called the FAA Airport Surveying – GIS Program (Airports GIS). Airports GIS will enable the FAA to establish more agile communication and coordination with airports as well as to facilitate better decision making using consistent and accurate data that has been verified through a rigorous quality assurance process, the agency informs. NextGen requires airports to submit a range of GIS information to the FAA. Terry Bills elaborates that as the world's civil aviation administrations move to the next generation air traffic control (NextGen in the US, Single European Sky ATM Research – SESAR in Europe), very accurate on-ground GIS inputs will be required to help ensure the safety of these GPS-based air traffic control systems.
Countries in the fast growing regions for air traffic volume like Asia too are sprucing up their technology to handle the traffic. India for example, is in the process of establishing centralised Air Traffic Flow and Capacity Management (ATFM) systems and will implement the central flow management systems by the year end. The ATFM shall rely on the geospatial data obtained dynamically through various subsystems such as aircraft flight profiles, weather, user preferred trajectories, special use airspace, surveillance data inputs from radars, automatic dependent surveillance systems and multi-lateration, informs Satish.
While technology is poised to be a key enabler for the more busier airports to manage their traffic, it has an equal significance for airports at the other end of spectrum too. As the world's less busy airports seek to attract more airline crowd, they will need to ensure quality services, improved safety and security in supporting air traffic growth. These airports also often have a large number of aeronautical data sources but are not always able to put them together meaningfully to be a decision support system. Geospatial technology can aid them in these efforts.
