There are optimistic and pessimistic views of the future of aviation. In the pessimistic view, the industry continues to be dominated by increasingly risk-averse corporations focused on incremental improvements that fail to keep pace with fast-rising fuel prices, climate change and disruptive advances in other industries. In this future, aviation fails to sustain the socio-economic benefit that has fueled its growth for more than 70 years.

In the optimistic view, global demand for air transport continues to grow, driven by the spread of wealth and desire to travel; advanced aircraft and biofuels curb costs and emissions; and technology opens the airspace to new uses of airborne systems. In this future, the industry puts in place infrastructures that allow a resurgence of innovation to make aviation ubiquitous.

The industry is entering a pivotal period. “As aviation has evolved from the 1920s and '30s to today, we have moved from the industrial age to the information technology/bio/nano age, and we are going into the virtual age,” says Dennis Bushnell, chief scientist at NASA Langley Research Center. “We are entering the age of tele-everything. There are an estimated 48 million telecommuters in the U.S., a third of the workforce, and one study suggests that tele-travel by 2016-18 will take 40% of business travelers off long-haul aircraft.”

Citing advances toward “five-senses” tele-conferencing in which all human body language is present, Bushnell argues: “In the late 1970s, the great decision was subsonic versus supersonic. Today it is physical travel versus virtual travel —and increasingly the virtual is winning because it is cheaper and saves time.”

Bushnell maintains that there is a societal change under way in how people interact that will shape the future of aviation. “A hundred million people worldwide spend more time in the virtual world than the real world. In 5-15 years, there will be a very different customer base for aviation.”

The view that virtual interaction will replace air travel is not shared by everyone. “It is very hard to imagine a future where people do not want to meet face to face at some point,” says David Vos, senior director for control technology at Rockwell Collins and a leading proponent of unmanned aviation. “There is a huge need to move things around—it's the nature of man. The question is how to enable it to happen more effectively.”

“We need to think in the broadest socio-economic context,” says Jaiwon Shin, NASA associate administrator for aeronautics. “The air travel market may not be as strong, but there is always the commerce aspect— the cargo need will still be there and nothing in the next 20-30 years will replace it,” he says. More affordable means of air transport, using unmanned cargo aircraft, could even open new markets.

“I am confident about the perpetual demand for passenger and cargo air travel, but I am skeptical about the growth rates,” says John Heimlich, chief economist for the Air Transport Association (ATA). The reason is the potential for fuel prices and emissions charges to push up ticket prices and deter travelers. “Airlines would have had greater growth in recent years if not for higher fares that priced people out of the system,” he says.

Fuel costs are perhaps the most immediate challenge facing aviation, as the energy demands from growing economies such as China and India outpace supply and drive up prices. “ATA's view is that we have to plan for a steady upward trajectory in fuel prices. They will outpace inflation, and we know fares won't,” says Heimlich. “Every five years we've seen a doubling in fuel price, and looking forward we see the same.”

The problem is that improvements in aircraft fuel efficiency are not keeping pace (see graph, p. 46). “A big part of the fuel-efficiency gain in the last two decades has come through load-factor improvements, from 60 to 80 percent, which allowed us to move a lot more without more. But we are reaching a natural ceiling on that,” he says. “It's hard to get more from the vehicle. We need to address air navigation and alternative fuels.”

Sufficiency and sustainability of energy threatens to be the major barrier to continued growth in air transport as global population and wealth increases. “The doom and gloom scenarios could be realized if nothing is done,” says Juan Alonso, associate professor of aeronautics and astronautics at Stanford University and former director of NASA's Fundamental Aeronautics program. But the potential for dramatic reductions in fuel burn and emissions does exist.

While at NASA, Alonso launched studies that showed fuel-burn reductions of 70-80% are possible within 40-50 years, if significant investments are made in technology development. “We are butting up against the laws of physics, but we need to do what we can to get as close as possible. Such savings cannot be realized by business as usual, and it's clear that many sectors of the industry want to continue on as they have in the past.”

“Aviation is so capital-intensive it makes companies more conservative and incremental. They will not take the risk. We see that tension all the time between Boeing Research & Technology and Boeing Commercial Airplanes,” says Shin. “The very long and capital-intensive development cycles are unique to this industry. People in government are impatient with the pace at which aviation is moving in bringing in new technology, versus the medical and IT industries, and are asking: 'Why does it take so long?'”

“If we want to handle climate change and hack fuel burn, we need to quit being so conservative,” says Bushnell. “We can't do [Boeing] 707s forever.” Aircraft lift-to-drag ratios—the key measure of aerodynamic efficiency—have been around 18 since the late 1950s, he says, arguing that new configurations such as the truss-braced wing (see p. 50) would make a dramatic improvement.

“Companies are far too conservative, and aviation is too much of a commodity. They have lost their eye of the future and are not checking their 6 o'clock for competition from the IT sector and small aircraft,” says Bushnell. “The U.S. planning cycle has become lethally tactical, and these issues are of strategic importance. I am at the upper range of strategic vision in terms of aviation, but I have seen more agreement recently as fuel prices go up.”

NASA, which eviscerated its aeronautics research budget in the early 2000s to shift funds to manned spaceflight, comes in for as much criticism as industry for being conservative. Shin says that is a reflection of the industry the agency is chartered to support. “With Airbus re-engining the A320 and Boeing looking at a new single-aisle, the direction of the subsonic large transport category is set,” he says. “For the next 20 years, in single-aisle and twin-aisle, from 100-600 passengers, the market is defined. There is not much room to wiggle, to introduce new technology.

“We know what's possible in the next 20 years, and many say it's not good enough in terms of local air quality or global climate change,” Shin says. “As automakers change to hybrid vehicles, aircraft are coming under tremendous pressure to do better.” This includes emissions charges in Europe and legal action by environmentalists in the U.S. aimed at forcing the government to set stringent limits on carbon dioxide emissions by aircraft. “If all other energy sources are renewable, and aviation is the only domain moving carbon from the ground to the air, the pressures will gain momentum,” says Vos.

The global aviation industry has set itself the targets of achieving carbon-neutral growth by 2020 and, by 2050, halving CO2 emissions from 2005 levels, but those goals look increasingly hard to achieve. “Over the last decade, we have replaced a lot of older aircraft, but that has not got us where we need to be to meet the 2020 and 2050 goals,” says Heimlich. “We need to buy new aircraft, we need manufacturers to provide advanced options, and we need to be able to afford them. Historically, the manufacturers have not let us down, but we need money for NASA and military R&D to push the technology frontier.”

And then, where should that money be spent? “The technologies and products for the next 20 years have been identified. Where do we go from here?” asks Shin. “The most logical place to go is somewhere different, in both subsonic and supersonic aircraft configurations.” That logic is shaping NASA investment in fuel-saving, emissions-reducing hybrid wing-body, truss-braced wing and other advanced configurations in which, so far, manufacturers and customers have shown little serious interest.

“Something different to tube-and-wing is needed for fuel-consumption reduction, and aircraft and engine manufacturers will be forced to address that,” says Shin. Airport noise and other emissions also have to be reduced before they place limits on aircraft operations. “It is back to the underlying issue we have all the time with aviation-industry economics—the biggest driver is reducing fuel consumption, and we have to latch on to that to reduce emissions.”

While the conventional tube-and-wing aircraft configuration is expected to dominate for the next 20 years, Shin believes the cargo sector provides a potential opportunity to introduce new designs. “Hybrid wing-body is getting greater support from the cargo community. The aircraft are quieter and less polluting. That opens up the possibility of 24-hour operations and expanding hubs, of convincing airports they will not mess up the community,” he says. “My guess is they will embrace new technology faster.”

Unmanned aircraft systems (UAS) may have revolutionized military aviation, but they have yet to make a dent in the commercial market because of barriers to accessing civilian airspace. Bushnell believes a huge potential exists for robotic vehicles carrying packages or people. Because of the connectivity provided by the Internet, “people can live anywhere. They can own 30 acres of mountaintop nowhere near a coastline. People have to be supplied with stuff and we can use small robotic aircraft to do it.”

“We keep talking about UAS for point-to-point cargo delivery, but we will not see that within next 20 years because of airspace system limitations,” says Shin. When it does happen, he believes it will involve aircraft larger than the flying delivery vehicles envisaged by Bushnell, operating on well-established routes rather than point-to-point on demand. “It could be feasible, but not in 20 years—maybe a little longer.”

Bushnell and others also see a market for robotic small aircraft to transport people, either autonomously or using unmanned technology to make them easy and safe for non-pilots to fly. “I see a cross between a closed carriage, a motorcycle and an ultralight, a flying Humvee and larger Cadillac versions for personal transport,” he says. “They could be a complete transportation system for places in the world without infrastructure.”

NASA is criticized from within its own ranks for not investing more in advancing technologies, such as electric propulsion, that would enable entrepreneurial development of personal aircraft and air taxis. “The aeronautics strategy is to satisfy the needs of current stakeholders,” says Mark Moore, an aerospace engineer at NASA Langley. While understandable, he says this “does not live up to our [National Advisory Committee for Aeronautics] NACA/NASA legacy of working on new frontiers, and doesn't align toward enabling new stakeholders to enter the system.”

Moore questions why NASA aligns the majority of its scarce aeronautics funds with an air transport market that is at an incremental stage of innovation, when emergent markets such as aerial robotics and on-demand aviation “are clearly trying to spring forward but are impeded because of the lack of federal attention to nurture them.” He believes NASA is sacrificing a potentially vibrant future for aviation in emerging markets to meet the near-term needs in entrenched markets.

“One reason NASA is not heavy on personal air vehicles is that they are not within 20 years in any stretch of the imagination,” says Shin. “I differ from the more optimistic view that there will be a lot of aircraft flying for personal transport. It could be a very exciting field to stimulate, to motivate innovation, and people criticize NASA for not helping the sector, but in my opinion [the government] staying away is helping them.”

Unmanned systems will give aviation no option but to change direction, argues Ian Poll, professor of aerospace at the U.K.'s Cranfield University. “The focus for decades has concentrated on moving people and cargo. But the last 10 years has seen the liberation of airborne systems to do much more,” he says. “[Unmanned] is not just about taking people off the platform; it's about doing new things with sensors and data.”

Defense and commercial aviation are diverging rapidly, he believes, with the civil market focused on its impact on the environment and how it can grow, while militaries are increasingly interested in intelligence and awareness. The commercial market will follow the military lead, once it is allowed to use UAS in civil airspace. “The problem is we have not got markets yet. The penny has not dropped,” Poll says.”But markets will appear that will draw out airborne capabilities in ways that boggle the imagination. The world is only beginning to realize the benefits of airborne systems.”

Poll believes the result will be a seismic shift in the industry's center of gravity away from the prime contractors that were forged in 20th century markets. “The future of aviation belongs in the SME [small and medium-size enterprise] domain. We will see a shift away from large corporations to small, innovative companies that can take orders of magnitude out of the cost and time to service,” he argues. “It's already happening. Every day governments are saying they can't afford legacy systems from legacy providers.”

Despite the environmental issues facing airlines and the airspace access hurdles holding back UAS, Poll says he is optimistic, not pessimistic, about the future of aviation. “A hundred years from now, we will look back and say, 'What a period of challenge that was for aerospace!'” he says. “But every good idea takes 100 years to take off. Look at the telephone, which we once used just to talk. The aircraft is like the telephone and we are now in the iPhone age. We have only just scratched the surface.”

Shin cautions against assuming the future will be as good for aviation as the past has been. “Aviation cannot be taken for granted. The aviation community is fairly biased; it says, 'What's the alternative? Air is the fastest, safest way to travel, at reasonable cost, with relative convenience,'” he says. “The industry has been sitting pretty in projecting three-times growth, but aviation could go through a self-correction similar to the financial market if airlines have to start charging $2,000 for a Washington-Los Angeles flight.”