The Air Traffic System: concepts & technologies

US Next Generation

Air Transportation System

 

The US FAA envisages a metamorphosis of the country’s ground-based air traffic control (ATC) network to the Next Generation Air Transportation System (NextGen) that provides air traffic management through the satellite-based Automatic Dependent Surveillance – Broadcast (ADS-B) system. Use of ADS-B, through an appropriate transponder, enables an aircraft to obtain its exact location from GPS satellites and continuously broadcast it with other flight information to other aircraft and ground stations, under the designation ADS-B Out.

At a higher level of ADS-B functionality, ADS-B In, aircraft can receive information from other aircraft and from ground stations, which contribute the radar-derived locations of non-ADS-B-capable aircraft in a Traffic Information Service-Broadcast (TIS-B) and weather information in a Flight Information Service-Broadcast (FIS-B).

The FAA designates ADS-B transmissions as critical services, actually used to separate aircraft, and TIS-B and FIS-B transmissions as essential services. Both pilots and air traffic controllers will view the same air traffic displays.

ADS-B more precisely determines the position of aircraft than the current radar-based ATC system, updating that position every second compared to every 12 seconds.

It uses a simpler, cheaper-to-install-and-maintain ground infrastructure, based on radio (instead of radar) stations that can operate from previously inaccessible areas such as mountains, allowing greater coverage. The network ultimately could include about 800 ground stations.

The improved air crew display introduces the possibility of airborne air traffic control, already demonstrated in the new concept of cockpit-based merging and spacing that allows optimized spacing on approach to an airport, with each aircraft flying a precise distance behind the preceding one.

UPS fitted its Boeing 757s and 767s with the Aviation Communication and Surveillance Systems (an L-3 Communications and Thales joint company) SafeRoute merging and spacing software application to allow its air crew to undertake those operations at the airline’s Louisville International Airport base and noted substantially reduced fuel use.

US Airways will evaluate SafeRoute on Airbus A330s at Philadelphia International Airport, leading to the development of standards for merging and spacing – and will also look at in-trail procedures over the Atlantic Ocean.

Alaska Airlines will evaluate a Honeywell ADS-B product at Seattle-Tacoma International Airport.

United Airlines also revealed that it will fit Boeing 747s with ADS-B for flights across the Pacific Ocean, which will allow reduced in-trail distances and optimized flight paths.

 

Single European Sky

Air Traffic Management Research

Eurocontrol, the European inter-governmental organization for the safety of air navigation, aims to develop a seamless continent-wide ATM system incorporating the 38 national air navigation service providers. While comparable to NextGen, the need to coordinate the ANSPs presents an additional challenge.

The Development Phase of the Single European Sky ATM Research (SESAR) program, begun in 2008, will continue to 2013, with the Deployment Phase to follow and continue to 2020.

The European ATM Master Plan seeks a European ATM system for 2020 and beyond that can enable three-fold greater capacity, with improved safety, reduced environmental impact and reduced cost to airspace users.

The ATM concept evolves from airspace-route-based to network-concentric, aircraft-trajectory-based, with four-dimensional (position and time) trajectories.

It will use a satellite-based primary navigation system, currently under development in the European Space Agency’s (ESA) Iris program, which could launch a geostationary earth orbit satellite in 2014.

The ATM system will also use an ADS-B based surveillance system. System Wide Information Management (SWIM) will aid information sharing and collaborative decision making.

The internet-protocol-based data/voice-transmitting Pan-European Network Service (PENS) for European ATC centres will replace the existing bilateral network.

 

Australian Developments

In late December Airservices Australia completed a country-wide ADS-B network, the first in the world.

It operates with ground stations at 28 of an envisaged 43 sites and provides coverage for the first time over some areas of the outback as well as the early warning of international flights from the north. Broadcasts occur twice every second.

The upgraded Australian Advanced Air Traffic System can process more than 1000 ADS-B flights simultaneously.

The Honeywell SmartPath ground-based augmentation system (the only GBAS to receive US FAA system design approval) under evaluation at Sydney Airport could receive CASA certification this year.

Similar systems could follow at Adelaide, Brisbane, Melbourne and Perth Airports.

SmartPath corrects errors in GPS signals to improve the positioning guidance to aircraft, allowing greater accuracy than traditional instrument landing systems at lower cost.

At the SmartPath ground station four receivers acquire navigation data from the GPS and a processor corrects the errors before broadcast to aircraft onboard Global Navigation Satellite System (GNSS) landing systems. The navigation data appears on aircraft displays in the same way as that from an ILS.

 

Performance-Based Navigation

Performance-Based Navigation (PBN) indicates a new approach to aircraft navigation that focuses on obtaining the shortest and most efficient flight path, including arrival and departure.

PBN encompasses continuous descent approach and four-dimensional trajectory management.

In addition to ground-based sensors (waypoints) and aircraft sensors it uses satellites.

General Electric (GE) has developed a flight management system (FMS) capable of four-dimensional trajectory operations including descent.

 

Avionics and Systems

Avionics now becoming available also examine visual and aural alerts to potential runway/airport traffic conflicts for air crews.

ACSS’s SafeRoute surface area movement management software application provides a cockpit display of aircraft and vehicle positions in the airport. It will undergo evaluation by UPS at Louisville.

Software updates to the Honeywell Enhanced Ground Proximity Warning System (EGPWS) produce the SmartRunway and SmartLanding improvement over its Runway Awareness and Advisory System (RAAS).

Honeywell could also develop airport moving maps, while Rockwell Collins has also revealed a RAAS. Electronic flight bags (EFB) provide aircraft of US Airways with moving maps or runway aural alert systems.

ITT and Sensis are working towards providing air crew with information that currently only air traffic controllers (at major airports in the US) receive, from the Sensis Airport Surface Detection Equipment, Model X (ASDE-X), obtained from transponders, multi-lateration systems and airport radar.

Technology continues to make piloting of aircraft easier. For instance, GE, which has already flown its four-dimensional-trajectory-operations-capable FMS on an unmanned aerial vehicle, expects that when it achieves the ability to control aircraft, cargo aircraft could fly with just one pilot.

As the range of equipment grows, coordinating them becomes more important.

Honeywell plans to produce the SmartView system that merges synthetic vision and enhanced vision system (SVS and EVS) data on a single screen, possibly with a camera image over part of the three-dimensional synthetic vision background.

The company could also introduce new features to primary flight displays (PFD), eg three-dimensional weather using its IntuVue weather radar.

Rockwell Collins is also considering the integration of SVS and EVS and the introduction of other sensor inputs, including weather radar.

Universal Avionics is focused on wide area augmentation system (WAAS) localizer performance with vertical guidance (LPV) approach capability.

Greater, though still relatively small numbers of UAVs will operate in civil airspace, for which they will require still-to-mature sense and avoidance and other capabilities.

 

Other Concepts:

Virtual Contingency Facility

In August 2009 the UK National Air Traffic Services (NATS) launched the world’s first certified remote airport control centre, the Virtual Contingency Facility (VCF), capable of controlling up to 70 per cent of the main control tower’s flights through London Heathrow Airport should that tower become inoperable.

It duplicates the main tower’s control room but without windows, and operators will employ the procedures used there when fog or low cloud prevents visibility.

The contractor NATS Services Ltd believes it can build a similar facility at any airport in the world.

 

The Evolution of the Air Traffic System

The evolution of air traffic system technology, that of a networked system with nodes on the ground at trans-continental and global distances, in the air and now in space, appears with a much lower level of perceptibility than the evolution of more tangible aviation technologies like aircraft and engines.

The evolution of other aspects of the air traffic system, operation and organization, also remain relatively difficult to perceive.

Air traffic system technology transitions from radar to radio equipment at ground stations and introduces satellites in the new sphere of space and new transponders, more capable flight management systems and new sensors for aircraft.

The new technologies require new air traffic operating concepts, or conversely receive direction from concepts newly envisaged, that include new relationships between aircraft and air traffic controllers and the development of airborne air traffic control and performance-based navigation.