IN FOCUS: Metroplex tests offer glimpse of NextGen

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Leaders of the team transforming the Washington DC region's air operations say they are "taking leaps forward into the NextGen era" with new precision-based-navigation (PBN) procedures and traffic routes.

The DC region is one of 21 "metroplexes" (see below) - large areas of congested, complex airspace - earmarked for extensive improvements by the US Federal Aviation Administration. The goal is to optimise efficiencies in the airspace with existing capabilities and on-aircraft technologies. The desired result is for users to get a taste of NextGen benefits in the near term: 2010-2015.

washington dulles airport, rex features

 © Rex Features

Dulles International is one of three major airports in the Washington DC Metroplex, where new airspace management techniques are in use

The DC Metroplex includes three major airports: Ronald Reagan National (DCA); Dulles International (IAD); and Baltimore-Washington International (BWI); plus about 15 reliever airports. Traffic volume is high. In the 12 months ending November, for example, IAD handled more than 328,000 aircraft operations and DCA, more than 281,000. BWI handles an average of 757 operations a day.

SIMULATION LAB

All stakeholders are represented in the 45-member team, 30 of whom are core. Subject matter experts include those from the FAA and Mitre, the agency's R&D partner; airlines with hubs in the Metroplex - US Airways (DCA), United Airlines (Dulles), and Southwest Airlines (BWI) - and the National Air Traffic Controllers Association.

Flight International observed the team in action at Mitre's simulation lab, IDEA, which stands for Integration Demonstration and Experimentation for Aeronautics. Here, researchers can explore concepts in a real-time simulator environment. The private, non-profit Mitre - located in McLean, Virginia - manages R&D for US government agencies.

In the lab, seasoned controllers from the Potomac TRACON and Washington Center sat at two rows of workstations. They were performing initial evaluation of a new routing they had designed to deconflict traffic flows from the western states into airports in the Metroplex.

"With the current routing, Reagan National arrivals are delivered on top of the Dulles arrivals and at some point cross," says David Perkins, FAA programme manager, design and implementation, DC Metroplex. To ensure safe separation on descent and observe crossing restrictions, aircraft make traditional "step down" approaches - in other words, they descend in altitude increments to the runway.

This means the aircraft must obtain a clearance to descend to each altitude, then maintain level flight until controllers issue clearance to the next lower altitude. This results in increased radar vectoring and pilot-controller radio communications, as well as a slowdown in arrival rates.

OPTIMUM DESCENT

In contrast, aircraft equipped to fly PBN-type procedures, such as area navigation (RNAV) approaches, would be able to perform an optimum descent profile (ODP), flying at reduced thrust in a continuous descent from cruise altitude to the final approach fix.

The difference between the step-down approach and the ODP is comparable with walking down stairs rather than sliding down the bannister. The controllers' redesign separates the traffic flowing into Reagan National, and an aircraft sliding down the bannister would require only one clearance from the en route structure to the terminal environment, says Perkins. In the lab, controllers continued to observe the flows of arriving and departing traffic moving across the flat-panel displays that served as simulated radar screens.

Meanwhile, the simulation increased the number of operations by 20% and cranked up the flow to five times normal to test the robustness of the design, says Jeffrey Davis, Mitre's lead multidiscipline system engineer for eastern and central integrated airspace and procedures.

About 90% of the bugs have been worked out of the design, says Davis. This initial test, or "scrub," precedes the first human-in-the-loop simulation tests aimed to validate if the design will work under worst-case scenarios.

aircraft on approach to washington ronald reagan national airport, rex features

 © Rex Features

A commuter aircraft overflies the Pentagon on approach to Ronald Reagan National

Controllers will not only observe flow, they will "work" the simulated flights, communicate with them as they would normally, and vary runway arrival and departure configurations for the DCA and IAD airports, as well as test the new route's effectiveness under different conditions and seasons, especially winter, when flights can encounter 150kt (280km/h) tailwinds. New PBN procedures to be introduced in the airspace have also been vigorously tested. US Airways, United and Southwest have each completed simulator validations for flying PBN-type procedures into their respective hubs in the Metroplex. The efficiencies gained in improved traffic management and flying new approaches are expected to yield near-term benefits for the user - "an improved airspace environment", says Davis. The team expects reduced delays for both arrivals and departures.

US Airways flight operations technical pilot and team member Brian Townsend emphasises the benefits of flying PBN procedures. "Fuel savings will vary with different aircraft," he says. "A level-off in an Airbus A320 at low altitude means burning about 15gal of fuel/min. If the aircraft is in flight idle profile, the burn drops to 4gal/min.

"Based on an average price of fuel at $3/gal, that means a significant saving. And multiply that by the number of aircraft flying a particular procedure annually, the numbers build quickly - as do the environmental benefits of reducing carbon and noise emissions. It also means airlines would fly fewer miles, and spend less time in-trail and in flight."

A continuous descent - which could be interpreted as a heart-thumping, roller-coaster slide to the runway - will in no way affect passenger comfort. Davis emphasises the airlines have seen to it that a steep angle of descent was not incorporated into ODP procedures. While a steep angle would have achieved optimal performance, those in the cabin come first. "We absolutely could not put passengers in an uncomfortable situation each time they landed in the Washington area," adds Davis.

The FAA has long touted the benefits that could be gained from its multibillion-dollar airspace modernisation. But in a dismal economy, where much of the aviation industry struggles to survive, not all users are confident they will be able to take the steps necessary to realise those benefits. While new production aircraft are RNP-equipped, operators of legacy aircraft would be required to invest heavily in avionics upgrades to fly PBN approaches.

Part of Mitre's mission is to fully address stakeholders' questions - "Why should I care? Why should I believe the FAA?" - by providing them a clear understanding of NextGen's capabilities and benefits, says Anthony Chambliss, Mitre programme manager ATM/CNS research and computing capability.

"Why should a carrier care when it's asked to invest in an avionics upgrade that would cost $50,000-100,000 per aircraft and has to face an 18-month ROI, and is aware that previous multimillion-dollar projects, like microwave landing systems, have failed," says Chambliss.

Davis says confidence is building as "the ideas and concepts in the [Metroplex] group are proving beneficial and not just glossy, high-level-view material".

Bennie Hutto, the National Air Traffic Controllers Association's vice-president Potomac TRACON, says the team expects to publish 15 STARs (standard terminal arrival routes) and 12 SIDs (standard instrument departure) procedures for the region's airports.

In February, five STARS - three for DCA, two for Dulles - will be submitted to the FAA in hope that the procedures will be published in July. The names for the procedures - for example, FRDMM ("Freedom") and TRUPS ("Troops") - and waypoints are intended to mark the 11th anniversary of 9/11. Remaining procedures will be submitted for publication during an approximate nine-month period. The remaining procedures will likely roll out over an 18-month period beginning September.

The team is also developing RNAV "Q" (high-altitude) and "T" (low-altitude) RNAV routes and a few conventional approaches for operators using non-RNP-equipped aircraft. They include those for Andrews AFB, which is not officially part of the DC Metroplex but is in proximity to its airspace.

A Metroplex team will continue its work in an innovative way. Townsend says that instead of devising procedures to accommodate the airspace, "we are adjusting airspace to accommodate new procedures".

METROPLEX PLAN USHERS IN THE NOW GENERATION

To lay the foundation for a planned 2025 rollout of NextGen, the US Federal Aviation Administration established the OAPM (optimisation of airspace and procedures in the Metroplex) plan.

Its goal: to realise maximum efficiencies in the near-term using existing technologies - an effort some in the industry describe as creating the "NowGen".

The FAA initiated the OAPM, or Metroplex plan, in response to the RTCA NextGen Task Force 5 recommendations of 2009, aimed at keeping NextGen deployment on track.

However, rather than work on a time-consuming and costly airport-by-airport basis, the agency tackled the effort on a regional scale.

It identified 21 US "metroplexes" - large swaths of congested, complex airspace typically covering a 150-200mi radius - that were prime targets for improvement, choosing Washington DC Metroplex and Dallas as prototypes.

The DC team views the key to success as making a collaborative effort to identify problems and create solutions for the benefit of all. As the saying goes: "Teamwork divides the task and multiplies the success."

Mitre's Jeffrey Davis calls this joint approach a "paradigm shift" for the FAA.

Traditionally, an FAA/industry initiative followed the "lead carrier" concept, says US Airways pilot and team member Brian Townsend.

For example, when developing new procedures for an airport, only the major carrier who used the airport as its hub would work with the FAA. In contrast, under the Metroplex plan all airlines collaborate and share information, Townsend adds.

In the Washington DC Metroplex, US Airways, United and Southwest avoid developing flight procedures that may raise issues among non-hub carriers operating into the metroplex. In addition, communication lines are open between operators and the FAA's Precision Based Navigation (PBN) Office (formerly the RNAV RNP Office).

The Metroplex effort demands sustained dedication from team members. A typical OAPM timeline, according to the FAA, averages about three years, from scoping period to implementation.

So far, the collaborative environment has yielded positive results for the DC Metroplex team since it started work in September 2010. It is developing 14 arrival and 15 departure procedures and designing new traffic flows.

The team is also developing Q (high altitude) and T (low altitude) RNAV routes and - for operators flying aircraft without PBN capability - new "conventional" routes. Metroplex airline participants have performed simulation validation flights for PBN-type flights and instituted training programmes for flightcrews.

The challenges are many, including the current economic crisis and associated funding cuts. However, FAA programme manager Dave Perkins says: "The people are everything. Collaboration is everything. The work is solution-driven, and people are dedicated to resolving the problems. When we realise we are on the same mountain together, we can move the mountain."