Record temperatures, melting glaciers and a score of increasingly dire scientific reports are sparking worldwide concern about climate change. And governments and industries are feeling the heat.
The growing importance of the "green" issue was underscored by a welter of activity in late September. Even with all the international discord, global warming topped the diplomatic agenda at the opening of the United Nations General Assembly, and the Bush administration — long skeptical of climate change — convened a forum of the 16 largest polluting nations to address the problem.
At the same time, the aviation community took up the issue at the semi-annual International Civil Aviation Organization (ICAO) assembly in Montreal. Like all polluting industries, aviation is being pressed to reduce its carbon footprint. While spotlighting the issue, the ICAO meeting also illuminated the division among nations about how to address it.
The flash point was a European Union (EU) backed emissions trading scheme that would have imposed a mandatory cap on aviation emissions. The EU has been using such a system since 2005 to help its members meet their commitments to the Kyoto Protocol on climate change.
The United States, along with many in industry, held fast for voluntary solutions and rebuffed the EU’s efforts. Calling the EU’s position "regrettable," Carl Burleson, director of the FAA’s Office of Environment and Energy, said "market-based measures, like emissions trading, may have value in trying to manage greenhouse gas emissions... but it should be done on the basis of consent between governments."
For its part, the United States is concentrating on technology efforts such as the Next Generation Air Transportation System (NextGen) to address environmental issues. Still in the preliminary stages, three key NextGen technologies and procedures — Automatic Dependent Surveillance-Broadcast (ADS-B), Continuous Descent Approaches (CDA) and Required Navigation Performance (RNP) — have the potential to produce a more efficient and cleaner National Airspace System (NAS).
Early tests of these technologies by cargo carrier UPS and Delta Air Lines provide reason for optimism. Still, there are many difficult hurdles to clear. On the positive side, these efforts are providing a basis for international collaboration on what is a worldwide issue.
NextGen is not primarily targeted at tackling global warming but at bolstering an already strained NAS. FAA forecasts that system by 2020 will have to manage a 30 percent jump in takeoffs and landings by passenger airlines, a 63 percent surge in general aviation hours and a 5.3 percent increase in cargo operations.
That growth alarms not only air traffic managers but also environmentalists. Operations and "emissions grow pretty much in lockstep," although there will be "some trail off" due to improvement in fuel efficiency, Burleson said.
In fact, airlines lowered their emissions profile from 2000 to 2006, thanks largely to the retirement of inefficient aircraft and reduction in vertical separation minimums in 2005, Burleson said.
In 2006, fuel efficiency for commercial airlines was 22 percent better than in 2000, according to the Air Transport Association (ATA). However, FAA projects total aviation fuel consumption, which had fallen off about 0.4 percent a year since 2000, will top 2000 levels this year and then grow about 4 percent annually through 2020. That trend presents a challenge for industry. Even as consumption dipped after 2000, airline fuel costs jumped 118.7 percent through 2006, according to ATA.
Fuel costs, however, provide environmentalists and FAA with a motivational tool. The airlines "are very price sensitive to the cost of fuel; they have a clear reason to become more efficient," said Janet Peace, a senior research fellow in the economics program at the Pew Center on Global Climate Change.
NextGen aims to drive down the growth rate of fuel consumption and emissions. FAA set a modest target of slowing the rate of emissions increase by 1 percent per year a few years ago and is assessing what the goal should be with NextGen, said Burleson. A new emissions target is "a good year away," however.
Meanwhile, green concerns are getting more and more attention in corporate boardrooms.
Eleven years ago, when UPS began exploring ADS-B, "we weren’t looking at environmental" issues, said Karen Lee, the carrier’s director of flight operations. Today "the senior executive team at UPS is very aware of the (issue), and one of the reasons they approved this project two years ago was pressure for improvement in ‘environmentals.’"
That approval cleared the way for UPS to acquire Boeing Class 3 electronic flight bags (EFB) and upgrade its aircraft surveillance capabilities, all prerequisites for ADS-B operations. ADS-B uses satellite signals rather than ground-based radar to manage aircraft operations and shifts much of the ATC responsibility to the crew.
"The system acts as an underpinning for air-traffic control procedures that can dramatically increase the capacity of the national airspace system," said John Kefaliotis, director of business development for FAA and Air Traffic Control programs with ITT.
FAA tapped ITT in August to build a 794-station ADS-B ground network by 2013 (Avionics, November 2007, p. 28). Those stations will receive via radio transceivers position reports from airborne aircraft and transmit that data, aeronautical weather and other pertinent information to ADS-B equipped aircraft.
Onboard the aircraft, the technology will operate on two levels: ADS-B "Out" transmits the aircraft’s GPS-sourced position every second to other aircraft and ground stations; ADS-B "In" receives aircraft position signals along with ground station data that can used to forge a real-time picture of traffic and build air-traffic management applications. Mandatory uptake of the avionics will stretch out to 2020, according to an FAA Notice of Proposed Rulemaking, issued in October, that would mandate ADS-B "Out" capability.
UPS plans to begin using ADS-B early next year on its Boeing 757 and 767 operations at its Louisville International Airport hub in Kentucky. The carrier plans to deploy the systems slowly over 2008, and have 107 of its 757s and 767s equipped by the first quarter of 2009, Lee said.
The aircraft also will be equipped with SafeRoute, an ADS-B "In" enabled software program developed by Aviation Communications & Surveillance Systems (ACSS), a joint venture of L-3 Communications and Thales Avionics. The program’s Cockpit Display of Traffic Information (CDTI) functionality will be hosted on the EFBs, manufactured for Boeing by Astronautics Corporation of America.
Based on test results, Lee predicts ADS-B operations will be "very effective" in cutting emissions. For example, UPS expects to wring 1,581 hours of excess taxi time out of its Louisville operations using SafeRoute’s Surface Area Movement Management (SAMM) application, reducing emissions on the ground and saving up to $936,000 a year in fuel burn. Those results become more impressive when projected over UPS’s worldwide operations.
Providing pilots with a detailed airport map, their position and other traffic, SAMM also functions as a runway incursion prevention system, said Christophe Hamel, market manager for SafeRoute at ACSS.
UPS also is expecting to get greater benefits from its ADS-B-aided CDAs.
"When you talk about the environmental impact, CDA is huge," said Basil Barimo, vice president of operations and safety at ATA. The procedure eliminates "the very inefficient ‘stepped approach’" and allows an aircraft, in optimal cases, to "glide in with engines at idle," he said.
These operations are "more difficult (to do) when you’ve got a mix of traffic with various capabilities approaching from different directions," Barimo said. However, "UPS is in a unique position since all the traffic in and out of Louisville at night is their flights."
The cargo carrier’s CDAs will be managed by SafeRoute’s Merging and Spacing application, which compresses and sequences arriving aircraft and "delivers them with minimum spacing to the runway," said Hamel.
Trial runs of NextGen CDAs yielded a "30 percent reduction in noise below 6,000 feet, a 34 percent decrease in NOx (nitrogen oxide) emissions below 3,000 feet and an overall reduction of 3 percent (in emissions) from cruise altitude to the runway," Lee said.
These gains are spurred by the elimination of inefficiencies in current operations. For example, "we are (often) forced down early. If we are coming in from the west, Kansas City generally starts us down at 130 to 150 miles out," Lee said. "The ideal descent point (from) 35,000 feet with average wind is 99 miles, so we are losing 40 to 50 miles of flight in a very efficient place which is high altitude."
However, the benefits of ADS-B for the NAS will come only with system-wide uptake of ADS-B Out capability, and that "will be a hugely challenging" task, Lee said.
For the airlines, the issue is return on investment. "The way it looks today, at least from an airline perspective, (is that) ADS-B Out doesn’t offer a lot of benefits beyond what we see with radar," since it does not diminish aircraft separations at least in the short run, said Barimo.
Affordable and user friendly retrofits are also a must, since most airlines will not be acquiring new aircraft to obtain the new technology, Lee said.
"The Class 3 EFBs we are using today are off to the side of the pilots," she noted. Ideally, they should be in front, on the navigation display, and the speed changes dictated by merging and spacing for CDAs should be integrated into the aircraft’s autopilot, she said.
Working with Georgia Institute of Technology, Delta recently completed the first phase of a CDA trial at Atlanta Hartsfield-Jackson Airport with "a small group of the Red Eye flights," said Mark Bradley, chief technical pilot at Delta. Instead of ADS-B, the carrier used the computer-based "Attila" managed arrivals system from ATH Group, of Lanham, Md., to sequence arrivals from the ground by dynamic monitoring of aircraft progress and asset availability at the destination. Aircraft speed is adjusted during flight to match the required time of arrival.
Trial data indicated "we could average (a savings of) 400 pounds of fuel per flight, which equates to 13 million gallons a year in Atlanta alone," Bradley said.
"We can see the advantages of ADS-B," including its ability to handle a mix of aircraft with different avionics equipage and provide more spacing accuracy, said Bradley. However, the NAS is not equipped with ADS-B yet, and Attila "provides the aircraft with a little more information, and at least gets us to the next phase of CDA."
UPS also performed some non-ADS-B CDAs this year but discontinued the approaches because they were "very difficult to manage," Lee said.
With RNP, the focus switches from the approach to en route operations. A form of area navigation (RNAV), RNP utilizes GPS with inertial reference system backup, allowing aircraft to fly predetermined paths loaded in their flight management computers. Accuracy is ensured through on-board performance monitoring, with a crew alerting system, if necessary.
When "you take the zigzags out (of the flight path), there is a lot less miles flown, a lot less fuel burn and therefore less emissions," said Lee.
"The flight path is central to the whole operation of the airplane. If you have the right path, then everything else flows from that," said Eric Nordling, vice president of marketing for Naverus, of Kent, Wash., a pioneer in the design of RNP approaches and departures ( Avionics, August 2007, page 24).
Naverus designs RNP procedures, including four-dimensional trajectory (4DT) CDAs. This year, the company became the first FAA authorized provider of RNP approach and departure procedures to airlines, fleet operators and airports. In May, Southwest Airlines tapped Naverus to provide an RNP program for its entire 737 fleet.
For 4DT approaches, RNP furnishes latitude, longitude and altitude information. The pilot provides the other dimension — time — by entering the desired runway arrival time into the flight management system. The aircraft speed will be adjusted en route by the system to meet the time requirements. Required time of arrival (RTA) capability is available on newer aircraft.
Naverus has designed two 4DT approaches for Boeing 737-800s at Brisbane Airport for Airservices Australia that have yielded an average savings per flight of 628 pounds of fuel, 1,970 pounds of carbon dioxide (CO2), 772 pounds of water and 7 pounds of NOx.
"RNP is tricky subject," Nordling said. Even though the concept is 11 years old, it still remains "too new" outside of Alaska, where it has been used as part of FAA’s Capstone program.
But environmental issues are helping spur adoption of RNP. For example, Southwest and Brisbane Airport cited environmental concerns as a key reason for their programs, Nordling said.
The next phases of the UPS and Delta initiatives are reaching beyond the United States and providing a basis for international collaboration.
UPS is eyeing Cologne, Germany, as the next base for CDA operations, Lee said. "It will be very complicated because you have to bring in about three different countries for the airspace," she said. "But luckily, all those countries have a common interest to lower fuel usage, noise and emissions." The carrier is looking to Eurocontrol as "the facilitator to get these procedures developed and implemented," Lee said.
Delta is slated to begin the next phase of its CDA tests next spring as part of the Atlantic Interoperability Initiative to Reduce Emissions (AIRE). Launched last summer, AIRE is a joint European Commission and FAA program designed to coordinate the NextGen and the Single European Sky ATM Research (SESAR) efforts.
The project involves a number of industry participants, including Airbus, Boeing, Air France-KLM, Scandinavian Airlines and FedEx.
For its part, Delta will begin testing CDA operations during the day, Bradley said. "It is going to be more robust and take a little more collaboration so we don’t interrupt regular operations," he said.
Environmentalists generally applaud the international efforts.
"Technology is absolutely critical," said Peace. But pollution "is really a huge problem. We have to have some massive reductions, and the least costly way to do that is with a cap and trading program."
Even as industry presses efforts to cut emissions, many questions remain unresolved about the scale and nature of the aviation’s contribution to climate change.
"Hyperbole characterizes the debate on aviation and climate change," according to Giovanni Bisignani, director general and chief operating officer of the International Air Transport Association (IATA).
In an article on the IATA Web site, Bisignani takes on the view that aviation is a major contributor to global warming and the "fastest growing source" of climate change emissions. "We are and will remain a small part of the big problem of climate change," he states.
As Bisignani notes, the United Nation’s Intergovernmental Panel on Climate Change (IPCC) pegged aviation’s contribution to global CO2 emissions at 2 percent and its overall contribution to climate change impact at 3 percent.
Projecting forward to 2050, the IPCC has aviation at 3 percent of global CO2 emissions and 5 to 6 percent of climate change impact. However, that is not where the story ends. The IPCC offers a number of cautionary notes and subjects for further study in its very detailed report.
Along with CO2, aircraft also emit water, NOx, soot and sulfur, all of which have an impact on climate. In addition, the affect of contrails and aviation emissions discharged directly into the troposphere and lower stratosphere are not well understood. There are suggestions that aircraft emissions may have a greater impact at those altitudes than on the ground.
"It is easy to calculate the carbon emissions of the aircraft industry; it is very difficult to determine what other effects they may have," said Spencer Weart, director of the Center for History of Physics at the American Institute of Physics in College Park, Md.
"There is very complex chemistry up in the stratosphere," he said. For example, "the ozone is very sensitive," and emissions could end up "doing away with ozone, which could actually be good for the greenhouse effect but bad for everything else."
At the AEEC symposium in Hamburg, Germany, in September, scientist Rex J. Fleming argued that climate models are flawed and that global "temperature is leading carbon dioxide" rather than the reverse. "The carbon dioxide problem — is it real or not? Is it a minor annoyance or an international catastrophe? My own opinion is that it has been oversold," he said.
Fleming represented SpectraSensors, of Rancho Cucamonga, Calif., which produces a diode laser sensor and air sampler used to measure atmospheric water vapor, or relative humidity. The sensor has been mounted on some 30 UPS 757s and certified on Lufthansa A319s. The affect of contrails, Fleming said, may be problematic, but "how much of a problem has not been quantified — that’s a legitimate complaint the (aviation) industry can make." He added, "you can’t solve the contrail problem with anything having to do with engines. You’d have to fly higher or lower or smarter."