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NEXTGEN UPDATE

September 2009

Category: Avionics for Business Aircraft

Author: Dave Higdon

THE WHEELS ARE TURNING
Next Generation ATC Gains Momentum…

Recent signs indicate long-awaited movement in advancing the U.S. Air Traffic Organization toward the goal of installing, implementing and using the Next Generation Air Traffic Control System – known as NextGen.

At its most optimistic, NextGen and the underlying technologies supporting it are designed to shift tracking and management of all instrument- and terminal-area flight operations to using satellite-based positioning data relayed through a system with real-time accuracy and information. The plan is to replace today’s system of ground-based traffic-monitoring radars and ground-based navigation aids and revise the system to take advantage of the higher accuracy and flexibility available from the NextGen technologies.

How all this will transpire remains to be seen - operators will be required to equip for the new technologies. And questions remain on how the changeover will be paid for, and what changes to operational flow and airport movements are still open and subject to debate and planning. Finally, a funding stream stable enough to keep the ultimate schedule on-track also remains to be seen.

An earlier FAA Notice of Proposed Rulemaking setting 2020 as the ultimate changeover date was later and quietly withdrawn; it generated more questions than it answered and highlighted what seemed to be a secondary treatment of private aircraft compared to air-carrier operators. Newer plans, while not formally proposed in the same vein, seem to be taking hold anyway, with a target of accelerating the changeover to operational status by the end of 2012 – slightly more than three years, at this point – with full change-over by 2018.

And throughout the debate, the accompanying funding arguments and operational disagreements, the big question for commercial operators remain open: how can this change-over help improve runway acceptance rates to the point that the tarmac stops being a routing choke point. Many questions remain – but progress is being made, even as the answers remain in flux.

NextGen Steps Occurring
In recent months these mileposts came along for Air Traffic Organization (ATO) and the Federal Aviation Administration (FAA):

• A contract signed in late July by ITT Corp. with the ATO-Terminal division worth $66.8 million to define, engineer and implement the next generation of airport-terminal ATC systems. Terminal-control operations, or TRACONs, generally handle arrival and departure traffic around busy airports at the core of Class B and Class C airspace, as well as the movement of instrument-operations aircraft within the terminal area. The contract is for one year with three single-year extensions possible.

• In June, Northrop Grumman signed a $33.9 million contract with the same FAA domain to provide program management and financial support, scheduling, metrics, performance analysis and risk management services for the ATO-Terminal operation.

• In late July the U.S. Senate’s Commerce, Science & Transportation Committee passed a $35 billion FAA reauthorization bill covering just two years and left in place existing funding mechanisms – while increasing fuel-excise taxes as agreed to by the private aviation community. The bill portends to accelerate the FAA’s development of NextGen but, at the same time, attempts to micromanage what Congress intended to be and act like a stand-alone business within the FAA – the Air Traffic Organization.

In other areas, the FAA is moving forward with the installation and implementation of the Automatic Dependent Surveillance-Broadcast network - or ADS-B - that provides the basic foundation of NextGen. But long-term work remains in terms of how the system change-over will be implemented.

Nonetheless, the FAA is refining its views and moving to make things happen. For example, earlier this year the FAA released a statement on NextGen and the movement to embrace RNAV and RNP wholly by 2025 for enroute and terminal operations.

The overall step toward Performance Based Navigation (PBN) puts more emphasis on the aircraft and its navigation systems having the ability to not only know its precise location, but to know how well it functions and its own accuracy.

As the FAA put it, “PBN is a framework for defining performance requirements in ‘navigation specifications.’ PBN framework can be applied to an air traffic route, instrument procedure, or defined airspace. PBN provides a basis for the design and implementation of automated flight paths as well as for airspace design and obstacle clearance.

“The two main components of PBN framework are Area Navigation (RNAV) and Required Navigation Performance (RNP). Once the required performance level is established, the aircraft’s own capability determines whether it can safely achieve the specified performance and qualify for the operation.”

The FAA’s Roadmap for Performance-Based Navigation is being incorporated into the agency’s NextGen Implementation Plan because several NextGen ‘solutions’ are dependent on RNAV and RNP to succeed.

Among those solutions are:
• Trajectory-based Operations, which use an aircraft’s flight path to help manage its flow through the system with minimal diversion;

• Arrivals and Departures at High-Density Airports, which could lead to the ability to safely increase the density and proximity of aircraft compared to the larger spacing standards needed today because of technological limitations of radar and transponders;

• Flexible Terminals and Airports, so-called because the NextGen technologies offer solutions for better managing the flow of aircraft between runways and gates and back to runways, safely and with maximum efficiency;

• Optimized Profile Descent, a time- and fuel-saving operational method for putting aircraft on a route direct to final and using a constant-rate single-step descent to the runway, eliminating vectoring and stepped descents.

To a limited extent, these technologies in various forms are already existent and used by some operators. For example, UPS employs a system that uses GPS, ADS-B and special proprietary software to conduct speed-managed constant-descent-profile arrivals to better managing arrivals into its huge Louisville International Airport hub and sort center.

While such goodies are excellent solutions for air carriers operating hundreds of flights into large hub airports every day, for the private operators who seldom use these facilities, some of the solutions are of limited value, particularly compared to the cost of equipage.

But other elements are already being fully embraced by the business aviation community and its suppliers, such as RNAV and RNP for navigation and flight-management avionics systems because of the increasing availability of RNAV/RNP procedures that can expedite a private aircraft’s access to satellite airports within the busiest Class B airspace sectors, such as Atlanta’s Peachtree-DeKalb, Chicago, Dallas and, of course, the New York-area TRACON’s airspace with its closely packed, high-traffic air carrier and general aviation airports. As of earlier this year, the FAA has authorized and created more than 265 RNAV procedures for use at 90 airports spread across 30 states.

Today’s GPS navigators approved for Instrument operations and enhanced with the Wide Area Augmentation System (WAAS) can use many of the RNAV I and RNAV II approaches; meeting RNP-level standards is already possible with avionics from some of business aviation’s best known avionics suppliers.

The benefits of these technologies plays out across Standard Instrument Departures (SIDs), Standard Terminal Arrival Routes (STARs) as well as instrument approaches themselves. The FAA has also developed RNP SAAAR procedures, or Special Aircraft and Aircrew Authorization Required.

These procedures, as the name implies, requires the aircraft avionics to meet RNP standards, and that the crew receive and clear special training for that procedure (the PDK SAAARs in Atlanta is an example, and follows a curved line – much like the old DME Arc – but with much higher accuracy). The procedure is designed to enhance the flow of traffic through high-traffic airspace and to provide precise routing to clear a large number of obstacles that otherwise require aircraft to stay higher and use less optimal arrivals into Peachtree-DeKalb.

ADS-B: NextGen’s Key Component
Today pilots can purchase portable devices with ADS-B-In capability, which means they can use these inputs to ‘see’ any aircraft within range that employs ADS-B-Out technology.

Several avionics makers are already offering ADS-B units – both Out, In and Out/In – in a variety of forms and technologies. With the potential to provide direct aircraft-to-aircraft traffic-awareness and avoidance, Automatic Dependent Surveillance-Broadcast has more than a decade of operational testing and use to its credit.

UPS started testing early ADS-B hardware developed by an avionics company it bought - IIMorrow, later purchased by Garmin International. And the FAA, using some similar hardware, paid to equip hundreds of private piston- and turbine-powered aircraft operating in Alaska under the Capstone Project; all this began in the mid-1990s.

In 2005, the FAA declared ADS-B ready to be operational, and since then and the formation of the agency’s Surveillance and Broadcast Services Office in 2005, the agency has moved forward with its plan to install hundreds of ADS-B ground stations around the nation. ADS-B services are already widely available across the Gulf of Mexico – an area targeted because of the high level of helicopter operations servicing the oil platforms there – and along the Eastern Seaboard and down into Florida.

Technology refresher
Although you have likely seen some of this in the past, a refresher on the technology seems worthwhile here – it is, as it stands, the technology that will allow the FAA to retire hundreds of slow, maintenance-intensive and comparatively inaccurate ground-based radar systems, after all.

ADS-B essentially works thus:
• An aircraft with either a special Mode S transponder or a special transmitter sends out – broadcasts – its exact position, altitude, speed and flight direction as provided by an on-board GPS;

• Any aircraft within range can pick up that broadcast signal directly or through a ground-station relay only if the aircraft is equipped with a receiver for the ADS-B broadcast signal – the so-called ADS-B In capability;

• Meanwhile, ground stations also receive all the ADS-B broadcast reports and relay them either by ground-link or satellite-link to the Air Traffic Control network where controllers can see the aircraft and the same position, speed, altitude and flight-vector data the ADS-B In-aircraft pilot sees.

What makes the ADS-B technology better and smarter? A number of elements make this technology attractive.

First, even here at the leading edge of the changeover process, the ADS-B Out and In hardware is not prohibitively expensive; in fact, some is priced about the same as a good replacement transponder that squawks your altitude to ATC radar.

Second, the ground stations are far less expensive than the radar systems they will replace – and they are far, far less maintenance-intensive… no rotating antenna, for example, and no high-power, high-dollar electronics for beaming out the radar signal to bounce off airplanes.

Third, ADS-B’s information is as accurate as the GPS – and these days, we’re talking accuracy levels as good as a couple of meters out of WAAS-enabled handheld navigators, as well as panel-mounted units.

Fourth, and most importantly, ADS-B Out broadcasts repeat several times each second – hundreds of times a minute. That means that all the data seen by controllers and other pilots is real time, and not (as is the case with en route radars), more than a minute old at each contact point.

And did we mention accuracy? Radar, as well as we’ve refined the technology since its invention at the start of World War II, has significant accuracy and reliability limitations – none of which plaque GPS or, in turn ADS-B.

It’s through the highly accurate, multiple hundreds of inputs per minute, that will, once all IFR aircraft are required to us it, make it possible for controllers to space IFR aircraft closer than today, both en-route and in terminal areas.

And when the sun sinks in the west, the accuracy and reliability of ADS-B should mean that controllers and pilots can be confident in using the same spacings as they use when the sun shines.

When, How and How Much?
Making the transition has a price tag of ‘$-tens-of-billions’ for the FAA and its users, but a solid number remains evasive – just as we still don’t know definitively when aircraft will be required to employ at least ADS-B Out.

A date of 2012 has been floated and rejected for IFR and Terminal operations, but the revised 2018 target seems to be gaining traction.

Equipment costs for the commercial and general aviation communities remains an issue; so does the current lack of a final technical standard – though some electronics makers are moving forward using existing TSO standards, knowing that what the FAA ultimately decides it wants may force some change.

Meanwhile, the FAA and the RTCA and the community are working to fix that standard for the NextGen solution. But already, large numbers of private aircraft operators are making the choice to equip since the ADS-B In/Out hardware works as an add-on to their aircraft’s existing Multifunction Display – the screen on which pilots see the ADS-B traffic around them.

In the end, the community hopes to nudge the FAA into retaining some value-added functions possible with ADS-B technology, such as the direct on-board delivery of weather images and airport weather data now available only through pay services that require an installed receiver about as expensive as ADS-B hardware.

Don’t be surprised to see the 2018 date take hold as the final target. And remember, it’s approaching faster than you think.

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