National Airspace System Plans

FAA planners’ efforts to devise a broad strategy to address capacity issues resulted in the Operational Evolution Plan (OEP)—the FAA’s commitment to meet the air transportation needs of the U.S. for the next ten years.

To wage a coordinated strategy, OEP executives met with representatives from the entire aviation community— including airlines, airports, aircraft manufacturers, service providers, pilots, controllers, and passengers. They agreed on four core problem areas:

•  Arrival and departure rates.
• En route congestion.
• Airport weather conditions.
• En route severe weather.

The goal of the OEP is to expand capacity, decrease delays, and improve efficiency while main taining safety and security. With reliance on the strategic support of the aviation community, the OEP is limited in scope, and only contains programs to be accomplished over a ten-year period. Programs may move faster, but the OEP sets the minimum schedule. Considered a living document that matures over time, the OEP is continually updated as decisions are made, risks are identified and mitigated, or new solutions to operational problems are discovered through research.

An important contributor to FAA plans is the Performance-Based Operations Aviation Rulemaking Committee (PARC). The objectives and scope of PARC are to provide a forum for the U.S. aviation community to discuss and resolve issues, provide direction for U.S. flight operations criteria, and produce U.S. consensus positions for global harmonization.

The general goal of the committee is to develop a means to implement improvements in operations that address safety, capacity, and efficiency objectives, as tasked, that are consistent with international implementation. This committee provides a forum for the FAA, other government entities, and affected members of the aviation community to discuss issues and to develop resolutions and processes to facilitate the evolution of safe and efficient operations.

Current efforts associated with NAS modernization come with the realization that all phases must be integrated. The evolution to an updated NAS must be well orchestrated and balanced with the resources available. Current plans for NAS modernization focus on three key categories:

• Upgrading the infrastructure.

• Providing new safety features.

• Introducing new efficiency-oriented capabilities into the existing system.

It is crucial that our NAS equipment is protected, as lost radar, navigation signals, or communications capabilities can slow the flow of aircraft to a busy city, automation system accurate aircraft position informawhich in turn, could cause delays throughout the entire tion. This more accurate information will be used to region, and possibly, the whole country. improve the efficiency of the system—the third cate gory of modernization goals.

The second category for modernization activities focuses on upgrades concerning safety. Although we cannot control the weather, it has a big impact on the NAS. Fog in San Francisco, snow in Denver, thunderstorms in Kansas, wind in Chicago; all of these reduce the safety and capacity of the NAS. Nevertheless, great strides are being made in our ability to predict the weather. Controllers are receiving better information about winds and storms, and pilots are receiving better information both before they take off and in flight—all of which makes flying safer. [Figure 1-4]

Another cornerstone of the FAA’s future is improved navigational information available in the cockpit. The Wide Area Augmentation System (WAAS) initially became operational for aviation use on July 10, 2003. It improves conventional GPS signal accuracy by an order of magnitude, from about 20 meters to 2 meters or less.

Moreover, the local area augmentation system (LAAS) is being developed to provide even better accuracy than GPS with WAAS. LAAS will provide localized service for final approaches in poor weather conditions at major airports. This additional navigational accuracy will be available in the cockpit and will be used for other system enhancements. More information about WAAS and LAAS is contained in Chapters 5 and 6.

The Automatic Dependent Surveillance (ADS) system, currently being developed by the FAA and several airlines, enables the aircraft to automatically transmit its location to various receivers. This broadcast mode, commonly referred to as ADS-B, is a signal that can be received by other properly equipped aircraft and ground based transceivers, which in turn feed the Other key efficiency improvements are found in the deployment of new tools designed to assist the controller. For example, most commercial aircraft already have equipment to send their GPS positions automatically to receiver stations over the ocean. This key enhancement is necessary for all aircraft operating in oceanic airspace and allows more efficient use of airspace. Another move is toward improving text and graphical message exchange, which is the ultimate goal of the Controller Pilot Data Link Communications (CPDLC) Program.

In the en route domain, the Display System Replacement (DSR), along with the Host/Oceanic Computer System Replacement (HOCSR) and Eunomia projects, are the platforms and infrastructure for the future. These provide new displays to the controllers, upgrade the computers to accept future tools, and provide modern surveillance and flight data processing capabilities. For CPDLC to work effectively, it must be integrated with the en route controller’s workstation.

Global Positioning System

The FAA’s implementation activities of the Global Positioning System (GPS) are dedicated to the adaptation of the NAS infrastructure to accept satellite navigation (SATNAV) technology through the management and coordination of a variety of overlapping NAS implementation projects. These projects fall under the project areas listed below and represent different elements of the NAS infrastructure:

• Avionics Development - includes engineering support and guidance in the development of current and future GPS avionics minimum operational performance standards (MOPS), as well as FAA Technical Standard Orders (TSOs) and establishes certification standards for avionics installations.
• Flight Standards - includes activities related to instrument procedure criteria research, design, testing, and standards publication. The shift from ground-based to space-based navigation sources has markedly shifted the paradigms used in obstacle clearance determination and standards development. New GPS-based Terminal Procedures (TERPS) manuals are in use today as a result of this effort.
• Air Traffic - includes initiatives related to the development of GPS routes, phraseology, procedures, controller GPS training and GPS outage simulations studies. GPS-based routes, developed along the East Coast to help congestion in the Northeast Corridor, direct GPS-based Caribbean routes, and expansion of RNAV activities are all results of SATNAV sponsored implementation projects.
• Procedure Development - includes the provision of instrument procedure development and flight inspection of GPS-based routes and instrument procedures. Today over 3,500 GPS-based IAPs have been developed.
• Interference Identification and Mitigation - includes the development and fielding of airborne, ground, and portable interference detection systems. These efforts are ongoing and critical to ensuring the safe use of GPS in the NAS.

To use GPS, WAAS, and/or LAAS in the NAS, equipment suitable for aviation use (such as a GPS receiver, WAAS receiver, LAAS receiver, or multi-modal receiver) must be designed, developed, and certified for use. To ensure standardization and safety of this equipment, the FAA plays a key role in the development and works closely with industry in this process. The avionics development process results in safe, standardized SATNAV avionics, developed in concurrence with industry. Due to the growing popularity of SATNAV and potential new aviation applications, there are several types of GPS-based receivers on the market, but only those that pass through this certification process can be used as approved navigation equipment under IFR conditions. Detailed information on GPS approach procedures is provided in Chapter 5–Approach.

Navigation Systems

Navigation systems are the basis for pilots to get from one place to another and know where they are and what course to follow. Since the 1930s, aircraft have navigated by means of a set of ground-based NAVAIDs. Today, pilots have access to over 2,000 such NAVAIDs within the continental U.S., but the system has its limitations:

• Constrained to fly from one NAVAID to the next, aircraft route planners need to identify a beacon-based path that closely resembles the path the aircraft needs to take to get from origin to destination. Such a path will always be greater in distance than a great circle route between the two points.
• Because the NAVAIDs are ground-based, navigation across the ocean is problematic, as is navigation in some mountainous regions.
• NAVAIDs are also expensive to maintain.

Since the 1980s, aircraft systems have evolved towards the use of SATNAV. Based on the GPS satellite constellation, SATNAV may provide better position information than a ground-based navigation system. GPS is universal so there are no areas without satellite signals. Moreover, a space-based system allows “off airway” navigation so that the efficiencies in aircraft route determination can be exacted. SATNAV is revolutionizing navigation for airlines and other aircraft owners and operators. A drawback of the satellite system, though, is the integrity and availability of the signal, especially during electromagnetic and other events that distort the Earth’s atmosphere. In addition, the signal from space needs to be augmented, especially in traffic-dense terminal areas, to guarantee the necessary levels of accuracy and availability.

The CAASD is helping the navigation system of the U.S. to evolve toward a satellite-based system. The CAASD analysts are providing the modeling necessary to understand the effects of atmospheric phenomena on the GPS signal from space, while the CAASD is providing the architecture of the future navigation system and writing the requirements (and computer algorithms) to ensure the navigation system’s integrity. Moving toward a satellite-based navigation system allows aircraft to divorce themselves from the constraints of ground-based NAVAIDs and formulate and fly those routes that aircraft route planners deem most in line with their own cost objectives.

With the advent of SATNAV, there are a number of applications that can be piggybacked to increase capacity in the NAS. Enhanced navigation systems will be capable of “random navigation,” that is, capable of treating any latitude-longitude point as a radio navigation fix, and being able to fly toward it with the accuracy we see today, or better. New routes into and out of the terminal areas are being implemented that are navigable by on-board systems. Properly equipped aircraft are being segregated from other aircraft streams with the potential to increase volume at the nation’s busy airports by keeping the arrival and departure queues full and fully operating.

The CAASD is working with the FAA to define the nation’s future navigation system architecture. By itself, the GPS satellite constellation is inadequate to serve all the system’s needs. Augmentation of the GPS signal via WAAS and LAAS is a necessary part of that new architecture. The CAASD is developing the requirements based on the results of sophisticated models to ensure the system’s integrity, security, and availability.