ATM Modernization, Commercial

Avionics Driving Efficiency Gains

By Ed McKenna | February 1, 2009
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Buffeted by a volatile fuel market, financial meltdown and economic downturn, the world’s airlines are navigating through some very challenging conditions.

After climbing back from six successive years of losses to post a $5.6 billion net profit in 2007, airlines are flying back into the red. The International Air Transport Association (IATA) estimates net losses for the industry in 2008 and 2009 will approach $10 billion.

A key culprit is fuel expenses, which even with the current declines are expected to boost operating costs. The airline fuel bill is projected to reach $223 billion, or 40 percent of operating costs in 2009 compared to 12 percent in 2002. On top of these costs, IATA projects a 3 percent and 5 percent drop, respectively, in worldwide passenger and cargo traffic for 2009.

Airlines have responded to the challenges by enacting fuel hedging strategies, trimming service, retiring older, inefficient equipment and even charging for baggage handling. For the longer term, the industry is looking to gain savings through technology, including Performance Based Navigation (PBN) and Automatic Dependent Surveillance-Broadcast (ADS-B).

Critical to FAA’s NextGen air-traffic modernization and the Single European Sky ATM Research (SESAR) program, the planned implementation of these systems stretches out more than a decade. But there is growing impetus from government and industry to speed up deployment. Airlines are investing in Required Navigation Performance (RNP) capability, and cargo carrier UPS has entered its second year using ADS-B to conduct Continuous Descent Approaches (CDAs) at its Louisville, Ky., hub.

"We want things to happen very quickly, but we are talking about some big very expensive programs" involving industry and government actions and investments which "is a little tricky," said Basil Barimo, vice president of operations and safety at the Air Transport Association (ATA), which represents major United States carriers.

The greatest headway is being made with PBN, since its requirements are more mature, and "all the NextGen capabilities are built around having performance-based navigation," said John McGraw, manager of FAA’s Office of Aviation Safety, Flight Standards Service.

PBN incorporates area navigation (RNAV), which gives aircraft flexibility to select more flight paths using ground and space-based navigation aids, and RNP.

American Airlines is using RNAV at Dallas/Fort Worth International Airport; Delta Air Lines at Atlanta Hartsfield-Jackson International Airport. The latter carrier has reported emissions improvements "equivalent to taking 15,000 cars off the road for a year," said Joe McCarthy, RNAV/RNP acting program manager with FAA’s Air Traffic Organization. "We have been looking at it as 3,000 or 4,000 gallons of fuel in a year."

In addition, Delta since August 2006 has used the "Attila" decision support tool developed by ATH Group, of Lanham, Md., to boost the efficiency of its arrivals into Atlanta. "Since that time," ATH Group says, "Attila has been working quietly to save Delta money, improve on-time performance and reduce greenhouse gas emissions."

Attesting to the value of the system, ARINC last April launched its "AirPlan enRoute" arrival-management service based on Attila technology.

A hosted system, Attila uses time-based sequencing to address inefficient, random flow of aircraft into busy airports such as Atlanta Hartsfield-Jackson, said Michael Baiada, ATH Group president. Requiring no additional onboard technology, the system monitors an aircraft’s progress once it is in flight at a stabilized cruise speed as well as the asset availability at the destination airport, such as gates, against airline goals.

Using the existing ACARS data link between the Delta Operations Control Center and pilots, Attila periodically recommends aircraft speed adjustments en route to address changing conditions.

"We are just moving aircraft a couple minutes; ATC still has to do what they do," said Baiada.

Major U.S. carriers, including Delta and American Airlines, have announced aircraft upgrades for RNP. In a fleetwide deployment, Southwest Airlines is investing $175 million over the next six years to implement RNP procedures at the 64 airports it serves. Southwest contracted with RNP consultant Naverus in May 2007 to design the program for its 737 fleet.

RNP uses onboard GPS with inertial reference system backup and sometimes distance measuring equipment to guide aircraft along pre-designed flight paths loaded in their flight management computers. Accuracy is ensured through on-board performance monitoring, with a crew alerting system.

RNP values, which designate the lateral performance requirement associated with a procedure, for most current approaches are 0.3 nautical miles either side of the centerline.

"RNP is what is really opening up the airspace, so we can go to a performance- as opposed to a rule-based system," said Lars Lindberg, president of Avtech Sweden, based in Akersberga, Sweden.

"The performance afforded by RNP, with the alerting in the cockpit and the tight constraints that are built into the procedure, allows for more predictable flight paths and better use of airspace," said McCarthy.

In practice, that means less separation between aircraft and more precise approaches.

Avtech and Naverus are working to design more efficient 4D Trajectory (4DT) approaches at Brisbane Airport in Australia and Arlanda Airport in Sweden. These approaches add the element of time to the latitude, longitude and altitude information that RNP furnishes.

These improvements translate into economic savings for operators. Extrapolating figures from the Intergovernmental Panel on Climate Change, Naverus estimates these airspace management changes could save the airlines 8 percent of annual fuel burn.

Highest Airport

In addition to Southwest, Naverus, based in Kent, Wash., boasts a cadre of international customers including WestJet, Air China, Air New Zealand and Qantas. Founded by two Alaska Airlines technical pilots, Naverus has designed RNP procedures for mountainous regions such as Air China’s service to Lhasa, situated at an altitude of 11,700 feet. Late last year, the company carried out a flight test to Bangda, Tibet, which at 14,200 feet is the highest airport in the world, said Steve Fulton, Naverus co-founder and chief technology officer.

Under the aegis of its parent company Boeing, Jeppesen also is developing RNP procedures for difficult-to-reach Chinese airports in Lijiang and Linzhi, said Nasos Apostolopoulos, enterprise manager, aviation data at Jeppesen.

Jeppesen also is contracted to establish RNAV procedures for locations in the Caribbean. "Many of our customers prefer (RNAV) as a first step toward RNP because you don’t need the expensive upgrades on the equipment and approvals to fly RNAV," Apostolopoulos said.

These initiatives are also gaining a lot of attention from countries that have not built out a ground-based infrastructure. Some countries are looking to bypass intermediate steps, such as ILS or even RNAV, and "go for RNP directly," said Apostolopoulos.

However, there is often a steep learning curve involved, and new adopters need to be told: "You can’t just turn a switch. Education is a big challenge," along with cost and complexity, said Fulton. "It is a big project and can be expensive."

Costs vary according to the age of an operator’s fleet. It can "cost in the hundreds of thousands of dollars to bring (an older) airplane up to snuff, whereas for a relatively new airplane we are talking tens of thousands," said Barimo.

While some older airframes were not designed for an RNP environment, many airliners are RNP-capable. At Operational Evolution Partnership (OEP) airports in the first quarter of 2008, more than 90 percent of major airline operations were RNAV-capable and about 60 percent RNP Rule 0.3 capable, according to a MITRE Corp. report. The OEP includes the largest United States airports.

"If you can get the industry to recognize the dormant capabilities in these aircraft, you can retrieve benefits really fast," said Lindberg. "That is what SAS has done (in Sweden) and they have realized quite a bit of fuel savings."

Still, all the recent activity belies the slow pace of performance-based navigation over the past decade. Pioneered by Alaska Airlines in the 1990s, RNP has been mainly used to provide "access to a field or an airport where a procedure was not feasible before" because of terrain issues, said McCarthy. RNP use and, for that matter, PBN generally, remains low in areas with high-density air traffic.

FAA had authorized more than 250 RNAV procedures at 86 airports and more than 130 RNP procedures at 45 airports. The effort has been augmented by Naverus, which has published some 350 procedures. Honeywell also is designated by FAA to provide RNP consulting.

"The challenge will be for FAA to keep up with the demand for new procedures," said Barimo. "We are clearly seeing a lot of investment in RNP and RNAV. In 10 years, we will be well on our way to a complete RNP/RNAV system."

Reinforcing the efficiencies of RNAV and RNP will be ADS-B, leveraging satellite navigation for reduced separations and more predictable arrival and departure planning. Under FAA’s proposed rulemaking, aircraft must be equipped for ADS-B by 2020.

"We think (RNP and ADS-B) really do go hand and hand," said Christian Kast, UPS advanced flight systems manager. "The RNAV arrival is the road on which aircraft travel, low RNP values allow for the most efficient path over the ground, and in a medium [to] high density ATC environment, (ADS-B enabled) merging and spacing allows the greatest number of aircraft to get to the runway as is possible on that RNAV road."

Among pioneers of the technology, UPS is testing ADS-B at its Louisville International Airport hub in Kentucky. The carrier at this writing had flown 87 ADS-B aided CDAs into the airport. CDAs eliminate the steps in a conventional descent and allow an aircraft, in optimal cases, to "glide in with engines at idle," Barimo said.

UPS is equipping its Boeing 757/767 freighters with dual Class 3 electronic flight bags (EFBs) and SafeRoute, an ADS-B "In" enabled software program developed by Aviation Communications & Surveillance Systems (ACSS), the joint venture of L-3 Communications and Thales Avionics. Cockpit Display of Traffic Information (CDTI) functionality is hosted on the EFBs, manufactured by Astronautics Corporation of America. Astronautics wrote the CDTI application based on an ACSS specification.

SafeRoute, at this writing deployed on six UPS tankers, supports surface movement and merging and spacing functions. The latter application uses ADS-B to gather information on inbound aircraft within about one hour’s flying distance from the hub, then calculates their optimum maneuvers to join the arrival stream at precisely spaced intervals. Merging instructions are presented to pilots on their EFB screens, which also show the relative positions and intended merge paths of other aircraft in the vicinity.

The application "uses the ADS-B broadcast of the preceding aircraft," to manage the arrivals, said Rick Ridner, ACSS staff engineer. "We work upon fixed-time spacing rather than fixed-distance spacing." A pilot enters the desired time separation and merge point; the system monitors the flight’s progress to ensure desired separation is maintained.

Merging and spacing reduces "the gaps in the spacing of aircraft arrivals in a medium to high-density ATC traffic environment," said Kast. "This enhances the throughput to the runway, thus improving capacity."

In the first year of operation, UPS pilots achieved 150-second spacing between lead and trailing aircraft, and consistent 6.1-mile separation, Kast said. Before the program, "arrival rates were varied and inconsistent enough that it affected the package flow rate into our ‘all points’ hub," he said.

The cargo carrier has saved between 250 and 465 pounds of fuel per flight. In the last 25 minutes of flight, the 757s registered a 21-percent decrease in fuel burn and the 767s a 31-percent decrease.

UPS also is operating CDAs to facilities in Ontario and Sacramento, Calif.; Cologne, Germany; Warsaw, Poland, and East Midlands Airport, U.K., "but these are not medium to high-density environments," said Kast.

Using a homogenous fleet for a defined period, UPS is "giving us great data for how these things could work in an optimum environment," said McGraw.

Late last year, FAA appointed ACSS to deploy SafeRoute on 20 US Airways’ Airbus A330s under a $6 million contract. The company is slated to demonstrate a prototype system by early 2010 at Philadelphia International Airport.

FAA awarded Honeywell a $3 million agreement to work with pilots from JetBlue and Alaska Airlines at Seattle-Tacoma International and Snohomish County Paine Field airports in Washington to develop requirements, standards and human factors analysis for ADS-B.

The agency also is designing "optimized descents" for less controlled environments. While less efficient than CDAs, these tailored approaches will yield benefits for the diverse fleets operating in the national airspace system. "Every aircraft doesn’t descend on the same path (and each) has its own optimal flight idle descent path," said McGraw.

In the future, another term — energy managed approaches — may arise, "reflecting the goal of minimizing the amount of fuel you burn coming to an airport," said McGraw.

Oceanic Efficiencies

Spurred by such environmental concerns, the United States is participating in international technology initiatives that also are delivering economic benefits.

The Asia South Pacific Initiative to Reduce Emissions (ASPIRE) is one such venture, involving Airservices Australia, Airways New Zealand and FAA. ASPIRE’s goal is to accelerate the development of operational procedures to reduce the environmental footprint for all phases of flight. As it reduces that footprint, the program also is reducing costs.

Under ASPIRE, United Airlines saved 1,564 gallons of fuel last November on a demonstration flight of a Boeing 747-400 between Sydney and San Francisco.

The carrier observed 11 fuel-saving initiatives, beginning with priority taxi out of Sydney and ending with a smooth, continuous descent approach in San Francisco, in itself pegged at saving "a couple hundred gallons of fuel," said United Airlines spokesman Jeffrey Kovick.

The flight was permitted to operate in restricted airspace over Sydney and used Dynamic Airborne Reroute Procedures (DARP), which allow for route adjustments to updated weather conditions. The carrier used its FANS controller-pilot datalink communications, designed by Boeing and United more than a decade ago for its 777 and 747 aircraft, to take advantage of these procedures to avoid a thunderstorm.

United also used FAA’s Advanced Technologies and Oceanic Procedures (ATOP) system. Replacing the current oceanic ATC system and procedures, ATOP integrates flight and radar data processing and provides for safe separation of aircraft in areas outside radar coverage or direct radio communication. It detects conflicts between aircraft, and sends data and aircraft position information via satellite to ATC. It also provides efficient tracks to aircraft over long oceanic routes.

United relied on the existing 747-400 technology with no modifications. "There was nothing reconfigured for the flight," Kovick said. The airline shared data from the flight with FAA, NASA and Airservices Australia, and was doing its own analysis of the results.

The United flight was the third ASPIRE demonstration flight. Last September, an Air New Zealand B777 conducted the first such test on a flight from Auckland to San Francisco. In October, Qantas followed ASPIRE procedures using the Airbus A380 on a flight from Los Angeles to Melbourne — its inaugural service using the superjumbo.

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