Air traffic control (ATC) is entering a new era with the increasing take-up of air navigation surveillance systems.
Technologies such as controller pilot data link communications (CPDLC), automatic dependent surveillance-broadcast (ADS-B) and airport surface detection equipment (ASDE-X) have massive potential to improve safety and operational efficiency.
CPDLC: opens up communications
In the 1990s, Eurocontrol convinced itself that air-to-ground data links would add value to the ATC system. CPDLC is now fully operational at the organisation’s Maastricht Upper Area Control Centre and planned for pan-European implementation as part of a wider ATC function.
CPDLC provides an alternative to traditional voice radio communications between ATC and pilots by opening up air-to-ground data communications, including the ability by both ATC and pilots to seek or grant clearances, determine flight routes, respond to messages and report information.
The Maastricht centre manages 260,000km² of seamless upper airspace above the Benelux countries and northwest Germany, and it is the second busiest ATC centre in Europe after London. The main benefit of CPDLC, according to aviation regulators, is a reduction in voice congestion. This means more efficient communications between controller and crew, and less chance of being misunderstood because messages can be written in addition to voice communication. Eurocontrol claims that during a typical year, CPDLC usage saves close to 160 hours of voice communication time.
Of course, the result of miscommunication can be devastating. In January 1990, Avianca flight 052 went down on its approach to New York with no fuel. Language misunderstandings and poor communication between crew and controllers were said to have contributed to the accident.
A key component of Eurocontrol’s ATC technology is the flight data processing system, which electronically processes flight plans and updates, correlating them to the radar tracks on the controllers display. This ensures that information on the flight’s progress is sent automatically to other controllers in other sectors or in adjacent centres.
CPDLC functionality, together with other leading-edge tools such as short and medium-term conflict detection systems, is included as part of the flight data processing system. The system is designed to help traffic control centres meet the growing demand for flights over Europe by handling more traffic, but with higher levels of safety, efficiency and environmental responsibility.
"The flight data processing system is based on an entirely different operating philosophy," says Peter Hendrickx, head of Operational and Airspace Systems at Maastricht. "It is trajectory-based rather than route-based. This means the controllers have the most accurate flight information at all times."
So, is it working? Eurocontrol figures show that, in 2009, an average 7.5% of flights in Europe were delayed by air traffic flow and capacity management, down from 11% of flights delayed the previous year, and the lowest delay rate since records began.
ADS-B: sidestepping radar surveillance
ADS-B is an available technology that provides aircraft position, altitude and speed information to air traffic controllers independent of conventional radar systems. ADS-B involves equipping aircraft with a broadcast transponder system to broadcast their position, as determined by their onboard Global Positioning System avionics. The aircraft position is then relayed via a ground station and the information is displayed on an air controller’s screens.
ADS-B technology effectively sidesteps radar surveillance. Radar is limited to update rates that are determined by the rotation rate of its antennas and, since it is a beam system, accuracy declines as an aircraft flies further away.
ADS-B provides ATC and pilots with much more accurate information to help keep aircraft safely separated, providing a live picture of the airspace and the planes in it. Both pilot and controller for the first time see the same real-time displays.
Sweden was the first country to install this technology in 2006, however, Australia is the first to roll out full nationwide ADS-B coverage with 57 ground stations operating at 28 sites. Meanwhile, China created one of the largest and most successful ADS-B systems covering 1,200nm across central China with over 350 equipped aircraft. The system has recorded almost two million incident and failure-free flights using ADS-B.
ADS-B continues to expand globally with parts of Southeast Asia, India, Europe and North America already using and further rolling out the technology.
Canada’s civil air navigation services provider NAVCANADA has used ADS-B technology to eliminate an 850,000km² radar coverage gap around Hudson Bay. The first ADS-B fly-past over the Hudson area was in January 2009 involving an Air New Zealand aircraft from London en route to LAX.
ADS-B is a prime component of the US Federal Aviation Administration’s (FAA) Next Gen programme that looks at efforts to transform air transport management systems from ground-based to more efficient satellite communications. The first commissioned ADS-B site in the US was southern Florida in 2008, although developmental systems have been online in Alaska and along the east coast.
The FAA estimates that delays could be reduced by at least 35% to 40% with full ADS-B coverage by 2018, and a typical twin-engine ADS-B equipped transatlantic flight could save 350lb of fuel per trip because aircraft are able to take a more direct route to their destination.
The Thales Group is one of the world’s largest developers of ATC systems. ADS-B is incorporated in its global Thales Eurocat system that includes radar processing, CPDLC, and automated conflict detection. It uses a distributed computing architecture and is capable of integrating geographically dispersed ATC units within a flight information region – control towers at different airports and en route control centres – into a single coherent system. Technology upgrades can be added as they are developed.
ASDE: detecting potential conflicts
As airports grow busier so does the potential for collisions on the airport surface. To help combat this, ASDE Model X (ASDE-X) is operational at a growing number of airports as a runway safety tool.
New York-based Sensis Corporation specialises in radar and passive sensors for airport surveillance and air defence. It is the prime contractor for ASDE-X use at 34 US airports. ASDE-X enables air traffic controllers to detect potential runway conflicts by providing detailed coverage of movement on runways and taxiways.
The data that ASDE-X uses comes from surface movement radar, multilateration sensors, ADS-B sensors, the terminal automation system and aircraft transponders.
The system essentially creates a constantly updated map of the airport movement area that controllers can use to spot potential collisions, especially helpful at night or during poor visibility.
"The improved situational awareness provides controllers with the insight needed to safely increase the efficiency of runway operations," says Mark Viggiano, chief operating officer of Sensis. "It is important to provide the controller with advanced conflict detection and alerting capability to enhance runway safety."