The concert lasted three hours, with the audience on its feet from the halfway point (when Don Henley began singing “Hotel California”) onward. When it was all over, it took another few hours to travel what would have been at most a 10-mile straight shot from the arena back to our apartment. My wife and I had no car (or driver) in China and usually traveled by subway, but our friend, wanting to show off her new Chinese-made Audi, had given us a ride. The jam in the parking lot, which had only two narrow exits for several thousand cars, was bad enough, but our routing across town was the real problem. Because of Beijing’s freeway-like ring-road layout and numerous one-way streets, we had to circle far around the city before we could head back in the right direction. And in addition to taking extra time, we used far more gas.
That wasteful car trip was an analogue for the exceptional wastefulness of air travel in China. The military’s control of the airspace around even the biggest commercial airports is the equivalent of having just a few narrow exits for a jammed parking lot—that is, planes must line up for a chance to pass through the narrow military-authorized corridors. And the military’s control of nearly all the airspace between Chinese destinations means that flights within China, even by the favored national carriers, sometimes must fly indirect routes that are the equivalent of going all around the city on a ring road.
Inefficient air-traffic control and airspace use is the main reason flights are more often delayed in China than in other major aviation countries; why their scheduled travel time, per mile flown, is much longer than in North America or Europe; and why they burn up to twice as much fuel per passenger mile in some stages of flight as their counterparts in Europe or North America.
Let me say that again: For reasons of sheer pointless inefficiency in routing, airlines in China can sometimes burn twice as much fuel and emit twice as much carbon as they would “have” to if they could fly more directly, with fewer delays. Commercial air travel in China could significantly expand with no increase in emissions if the air-traffic system there worked the way it does in the rest of the world. The situation is similar to the burden created by China’s legacy building stock—the architectural remnants of the Mao era and the early reform years that were so cheaply built and poorly insulated that they take twice as much energy to heat and cool as their Western counterparts. Replacing all those old buildings with greener modern structures will take many years, and billions of dollars. Relatively speaking, wasteful airline routing could be corrected cheaply almost overnight.
There is one more fuel penalty imposed by military control of the airspace. Modern airliners generally work more efficiently the higher they fly. With their great speed and enormous mass, they generate disproportionate drag if they fly through the relatively thick atmosphere below about 20,000 feet. More of their fuel goes simply to overcoming wind resistance. Everywhere else in the world, commercial jetliners spend their cruise time at 30,000 feet or above. In China, military restrictions may keep jets at 10,000 or 15,000 feet, where they become the equivalent of gas-guzzlers.
Ending this sheer waste will require the cooperation of the Chinese military, but it will also be sped up through a new technology for navigation based on a particular application of the GPS revolution that has transformed all other forms of travel. When the first “instrument flight courses” were created in North America in the 1920s, they were open bonfires, or flares in baskets, whose light the Lindbergh-era aviators could try to follow from one waypoint to the next. By the early 1930s, airplanes had their first true, if crude, instrument guidance. This was the “four-course radio range,” in which groups of towers broadcast the Morse code for either the letter A or N—A being dot-dash, N being dash-dot—and pilots judged their direction by which letter they were hearing (a solid tone—the A and N combined—meant that they were on course). By the early 1950s, this was replaced by the then far-superior VOR (for “very high-frequency omnidirectional range”) system, which is still a mainstay of navigation in most of the world. This is a network of beacons that send out a different signal for each of the 360 degrees of the compass, so that planes with the right equipment could fly, for instance, the 90-degree “radial”—due east—from one of the stations, or the 270 radial—due west—from another. But with the coming of GPS, a true revolution in air travel was possible.
For cars, GPS simply means that we no longer have to get lost (even if people who know a neighborhood can often improve on the suggestions of the voice in the device). For air travel, GPS offers a series of related improvements. An obvious one is more-direct routing, cutting the corners off the indirect, jagged courses marked by VORs, with consequent savings in time, fuel and carbon emissions. Another is reduction of the airport nuisance factor in big cities. The combination of very precise real-time GPS readings, which can locate even a fast-moving airliner within a space of a few feet, and sophisticated new autopilot systems that can follow a very tightly defined path, now allows planes to fly slalom-style courses through the sky that were once inconceivable.
With older VOR-based navigation, which prevailed around the world until the early 2000s, the “airways” that ran from one point to the next were eight to 10 miles wide. That was the margin of error allowed planes on cross-country flights. Now the paths that airliners can fly—on departure, to avoid noise-sensitive areas of a big city, or on descent, to avoid hills and towers on the way to a remote or difficult landing site—have a margin of error of a wingspan or two, or a few hundred feet rather than tens of thousands.
Why does this matter? Noise abatement for one, since the planes can more precisely follow paths that minimize neighborhood disruption. But the fuel savings are also significant. When the new path has been calculated to let the plane glide continuously down toward the runway, the final-approach stage of the flight, which involves leveling off several times in a stair-step descent, requires only a third as much fuel as the conventional method.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.