Image: NASA/JHUAPL SCREEN SHOT shows what air traffic controllers using ITWS in the New York City area see. Because this system tracks bad weather more accurately than current forecasting tools, it makes it easier for controllers to handle more planes at once and to reduce delays.

Ever try to nap on a bank of cold, plastic airport chairs? Make more than one meal of microwaved pizza in a day? Break down crying in front of an arrivals and departures board? Almost everyone has at least one horror story about being stranded in an airport¿in no small part because flight delays are becoming increasingly common.

Last year the number of flight delays in the U.S. rose by 20 percent, according to figures released by the Federal Aviation Administration (FAA) last month (see sidebar). Part of this increase comes from the simple fact that each year, more planes take to the skies. But the majority of flight delays¿a full 68.7 percent of the total¿occur because of bad weather.

With that in mind, scientists at the Massachusetts Institute of Technology¿s Lincoln Laboratory have developed an improved weather forecasting system, now completing its testing at four New York City-area airports: John F. Kennedy International, Newark International, LaGuardia and Teterboro. So far, the system¿called an Integrated Terminal Weather System (ITWS)¿appears to be a success. According to a analysis MIT released on February 16, ITWS saved airlines and passengers more that $150 million by reducing 49,000 hours' worth of flight delays in the New York area in 2000.

Compared with current forecasting tools, ITWS arms air traffic controllers with a much sharper picture of developing weather patterns, which makes it possible to handle more planes. For instance, because the system closely tracks the movement of storm cells, controllers can actually land planes safely during gaps in passing thunderstorms. ITWS also gives more accurate predictions of windshifts and gust speeds. Thus, during coastal storms¿which often come with strong, high-altitude winds¿controllers can better judge how long it will take planes to fly certain distances and can land more of them per hour.

To create its forecasts, ITWS uses a variety of sophisticated algorithms and data from seven different radar sources, sensor-equipped planes, a national lightning sensor and a number of systems that monitor surface winds and temperatures. Putting the information together, it pinpoints the location of storms to within one kilometer¿and then calculates where they will be in the next 10 to 20, 30 and 60 minutes. It also predicts tornadoes and microbursts¿sudden downdrafts of air that are especially dangerous to planes during takeoff and landing. And unlike the National Weather Service¿s NEXRAD reports, which come out every six minutes, ITWS updates every minute.

Image: NASA/JHUAPL COMMUNICATION among ITWS users is essential for making decisions about routing planes in bad weather. So ITWS displays were installed not only at the main airport towers in New York but also at several other traffic control centers. Major airline operators, too, had access to ITWS data.

"There¿s a lot out there, and the key thing we do is grab it all, combine it and translate it into a form that can be used easily," M.I.T. senior staff researcher James E. Evans says. "We don¿t want to show raw data on the screen. We want to take the information, update it continually and display it seamlessly."

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