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 airportin 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 delaysa full 68.7 percent of the totaloccur because of bad weather.

With that in mind, scientists at the Massachusetts Institute of Technologys 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 systemcalled 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 stormswhich often come with strong, high-altitude windscontrollers 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 kilometerand then calculates where they will be in the next 10 to 20, 30 and 60 minutes. It also predicts tornadoes and microburstssudden downdrafts of air that are especially dangerous to planes during takeoff and landing. And unlike the National Weather Services NEXRAD reports, which come out every six minutes, ITWS updates every minute.


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.

"Theres 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 dont want to show raw data on the screen. We want to take the information, update it continually and display it seamlessly."

The ITWS screen that air traffic controllers see shows weather systems superimposed on a familiar map. Storms appear as swirls, and areas experiencing rain or wind shear are highlighted. Blue lines mark storm movements in the near future, while yellow areas reveal where storm lines will fall within half an hour to an hour. Information alerts on the screen are visible from 10 feet away. And controllers can get an overview of an area having a radius as large as 100 miles, or they can focus in on a region as small as a city block.

The ITWS system was initially developed with funding from the FAA. The M.I.T. team installed it at the New York airports as a demonstration in 1998, with additional funding from the Port Authority of New York and New Jersey. Similar tests were carried out in Memphis, Dallas and Orlando. The scientists introduced several improvements to ITWS in the summer of 1999. It will be replaced for good in 2002, when the FAA's production version, built by the Raytheon Corporation in Lexington, Mass., will be ready.

During its tenure, ITWS has given the scientists and airports a better understanding of weather-related delays in and around New York. The M.I.T. study discovered, for instance, that both near and distant thunderstorms caused about 40 percent of all arrival delays at Newark between 1998 and 2000. Another 27 percent came from low ceiling and visibility problems. And 16 percent of arrival delays resulted from high winds in otherwise fair conditions. These delays could be further avoided, the scientists say, if ITWS were extended.

"All the major airports of this country, not only those in New York, will benefit from the Port Authority's support for making the ITWS better meet the airline passenger needs for safe, delay-free flights," Evans says. In fact, the FAA plans to deploy 34 integrated weather systems based on ITWS in support of 47 major airports by 2003.