The Continental flight that made an emergency landing in Miami Monday morning points to a nagging problem: How can commercial airlines and air-traffic controllers alike do a better job of helping planes avoid in-flight turbulence?
At about 4:30 a.m., a Continental Airlines Boeing 767 bound for Houston from Brazil hit a turbulent pocket of air in the skies between Grand Turk Island and Puerto Rico. Emergency responders at Miami International Airport said 26 of the 179 people on board were injured, four seriously.
This comes less than two months after Air France Flight 447 flew through areas of severe turbulence shortly before it crashed.
The two incidents are adding urgency to research aimed at developing new tools for predicting where turbulence is likely to hit.
The problem defies any single solution, says John Hansman, a professor of aeronautics and astronautics at the Massachusetts Institute of Technology in Cambridge. Pockets of turbulent air can appear and disappear quickly. Thunderstorms, with their strong updrafts and downdrafts, give few clues about the state of the air several miles away. And clear-air turbulence leaves no visual clues at all.
Here are several examples:
Mapping the wind
The National Weather Service is now using a system that analyzes wind patterns from weather forecast models to map areas where turbulence is likely to appear and how strong it could be. The system is operational for altitudes above 20,000 feet; scientists are working on a version that will be useful down to 10,000 feet.
Listening to the echoes of raindrops
At the same time, scientists are fine-turning a way of using data from the National Weather Service's Doppler radar to find regions of severe turbulence within thunderstorms. Essentially, they use the echoes from raindrops in the clouds to determine where the air is most turbulent.
The idea: Where you see raindrops exhibiting the widest range of motions, that's an area you want to avoid.
It's now a matter of turning these results into products the FAA can approve, Dr. Williams says.
Two years ago, Williams and his colleagues provided United Airlines pilots with prototype maps of turbulence in storms along their routes. Pilots reported that they found the data "very helpful" in helping them decide if they needed to request a route change to avoid storms and turbulence.
Charting a storm’s shape
Another approach combines satellite images and radar information about a storm's shape with a sophisticated computer model to give pilots a sense for how likely they are to encounter turbulence in the clear air around a storm. A prototype has been running for about a year, says Williams, who has been working on it with colleagues from the University of Wisconsin at Madison, the US Naval Research Laboratory in Washington, and MIT's Lincoln Laboratory.
The group is now working on an approach that builds on these to yield global air-turbulence forecasts.
Improving plane-to-plane talk
Still the best probes of turbulence ahead will remain the airliners in front of you along the route, says Dr. Hansman.
A crucial piece of the puzzle, especially for transoceanic flights, involves improving air-to-air communications among planes along a route, as well as accurate in-cockpit information on where the other airliners are at any moment, he says.
This, he adds, would give pilots a freedom they don't have now to alter their course to avoid turbulence.
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