The U.S. FAA recently spelled out the performance requirements for aircraft-tracking equipment that will be required under the Next Generation Air Transportation System (NextGen). New avionics capabilities will allow aircraft to be controlled and monitored with greater precision and accuracy by a satellite-based system called Automatic Dependent Surveillance - Broadcast (ADS-B).
“Today we have reached a major NextGen milestone,” said U.S. Department of Transportation Secretary Ray LaHood. “This technology represents another step forward in our ability to make America’s skies the safest in the world.” Currently, aircraft are controlled based on a radar system that, unlike a satellite global positioning system, is negatively affected by weather.
The final rule, published in the May 27 Federal Register and developed with extensive input from the aviation community, requires aircraft flying in certain airspace to broadcast their position via ADS-B by Jan. 1, 2020. The rule mandates that the broadcast signal meet specific requirements in terms of accuracy, integrity, power, and latency.
“This rule gives the green light for manufacturers to begin building the onboard equipment that will allow our air traffic controllers to know where aircraft are with greater precision and reliability,” said FAA Administrator Randy Babbitt. “That is one of the key elements of NextGen that will improve the safety and efficiency of flight.”
Some of this information is now being broadcast free to aircraft equipped with ADS-B in special prove-out zones including the Gulf of Mexico, South Florida, and in the airspace above Louisville, Philadelphia, and Juneau. Those areas were chosen as key sites to roll out ADS-B due to challenges presented by vast stretches of water, rugged terrain, and traffic congestion. These areas also are populated by aircraft already equipped with ADS-B. The nationwide rollout of ADS-B ground stations will be complete in 2013.
By 2020, the FAA will require ADS-B equipment for aircraft flying in airspace including Classes A, B, and C, around busy airports, and above 10,000 ft.
The May 27 rule addresses mainly “ADS-B out”—the transmission of data from the aircraft to ground control. Because the benefits of “ADS-B in”—transmission of data into the aircraft—are not yet quantified, the FAA is not prepared to issue a rule on that aspect, although certain requirements of the May 27 rule support some ADS-B in applications. With ADS-B in, cockpits will have access to the same information and visual displays as air traffic controllers, allowing pilots to make decisions that will further increase the safety and efficiency of the air traffic system. Transponders are still required under the rule.
It has not yet been determined to what extent, if any, the federal government will subsidize expenses associated with ADS-B equipage. The FAA estimates that the rule will entail industry equipage costs of between $2.5 billion and $6.2 billion ($3.3 billion to $7 billion overall, including government costs). Overall estimated benefits are $6.8 billion to $8.5 billion. All figures apply to the years 2009-2035.
Operators will have two options for equipage: the 1090-MHz extended squitter broadcast link or the Universal Access Transceiver broadcast link (978 MHz). The 1090 MHz ES broadcast link is the internationally agreed upon link for ADS-B and is intended to support ADS-B in applications used by air carriers and other high-performance aircraft. The 1090 MHz ES broadcast link does not support FIS-B (weather and related flight information) because the bandwidth limitations of this link cannot transmit the large message structures required by FIS-B, according to the FAA. The UAT broadcast link supports ADS-B in applications and FIS-B, which are important for the general-aviation community.
In a related matter, the FAA on May 26 awarded three NextGen contracts to Boeing, General Dynamics, and ITT totaling up to $4.4 billion over 10 years. ADS-B is the cornerstone of NextGen, which is an umbrella term for the ongoing, wide-ranging transformation of the national airspace system (NAS). At its most basic level, NextGen represents an evolution from a ground-based system of air traffic control to a satellite-based system of air traffic management with the goal of a safer, more efficient, and higher-capacity NAS. Those goals will be realized through the development of aviation-specific applications for existing, widely used technologies, such as the global positioning system and technological innovation in areas such as weather forecasting, data networking, and digital communications.
Under the contracts, the companies will perform work that will demonstrate NextGen procedures in real time on a large scale within the current air traffic system. Large-scale demonstrations, including the use of aircraft as flying laboratories, will be performed to see how NextGen concepts, procedures, and technologies can be integrated into the current system.
The FAA will work with these companies to develop and demonstrate new procedures in four dimensions, adding the element of time to the current three-dimensional profile of an aircraft’s latitude, longitude, and altitude. Introducing time to this profile means that under a fully developed NextGen system, pilots and controllers will know not only where an aircraft is with greater precision but also when the aircraft is supposed to be there. Unlike the current system of “roads in the sky,” 4-D operations will allow aircraft to fly from Point A to Point B more directly, while taking into consideration factors such as heavy traffic and bad weather, according to the FAA.
The development and rollout of modernized weather services is among the other work to be performed by the companies.