A practical new approach to holographic video could also enable 2-D displays with higher resolution and lower power consumption.
A weather forecasting system developed by the MIT Lincoln Laboratory and tested at four New York-area airports saved airlines and passengers more than $150 million last year by reducing delays by 49,000 hours, says an MIT report published February 16.
Lincoln Laboratory's Integrated Terminal Weather System (ITWS) provides accurate, easier-to-use storm and wind forecasts that allow Federal Aviation Administration (FAA) air traffic controllers to make better-informed decisions. The ITWS was developed with FAA funding. A special demonstration system for the New York area was created with funding from the Port Authority of New York and New Jersey.
The New York ITWS demonstration system helped reduce delays by providing predictions of storm movements so that planes could safely land and take off during gaps in thunderstorms; information on high-altitude winds that enable controllers to land more aircraft per hour when coastal weather is present; and information on storm activity that allows more New York-headed planes to take off when storms are weakening and more planes to be handled safely.
Combining data from radar sources, sensor-equipped planes, a national lightning sensor and a multitude of systems reporting surface winds and temperatures, the ITWS can reliably locate storms to within 1 kilometer and provide minute-to-minute updates. The system's wind speed data helps controllers judge the amount of time it will take an aircraft to cover a certain distance.
"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. That's where MIT technology comes in. We don't want to show raw data on the screen. We want to take the information, update it continually and display it seamlessly," said MIT senior staff researcher James E. Evans, co-author of the report.
With ITWS in operation, it was possible to better identify the principal causes of delays as thunderstorms, low cloud ceilings and impaired visibility. Many of these delays could be avoided, the study's authors reported, if ITWS acquired additional forecasting capabilities.
The MIT-developed demonstration system in use since 1998 will be replaced in 2002 with the FAA's production version, produced by the Raytheon Corp. of Lexington. Through the Port Authority funding, Lincoln Laboratory has developed enhancements to ITWS that will be incorporated into the Raytheon production systems.
"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," Dr. Evans said.
The FAA will deploy 34 integrated weather systems to provide coverage for 47 major airports by 2003.
A COOPERATIVE APPROACH
The classical approach to reducing airport delays has been to expand capacity by building more runways. This is not feasible at the New York airports, so this effort seeks to use information technology to increase the bad weather capacity of the airports.
"The Port Authority has been a national leader at creating cooperative programs with the FAA and the airlines to address complicated issues such as adverse weather impacts on the New York airports," Evans said. "Creating a real-time system of research equipment connected to FAA radar requires very good cooperation, which the Port Authority effectively orchestrated."
A USER-FRIENDLY SYSTEM
As an experiment, a demonstration ITWS was introduced in fall 1998 to help reduce aircraft delays at four New York-area airports: John F. Kennedy International, Newark International, LaGuardia and Teterboro.
In summer 1999, ITWS was enhanced with the ability to provide 30-60 minute convective storm predictions generated by the Terminal Convective Weather Forecast (TCWF) algorithm. Many of the thunderstorms in the New York area are line storms consisting of many individual storm cells that last only about a half hour, while the line storm itself lasts for several hours. Because the individual storms move very differently than the longer-lasting line storm envelope, it has been difficult to predict line storm motion. The MIT-developed TCWF software accurately determines the motion of the line storm and predicts where it will be up to 60 minutes in the future.
A COLORFUL DISPLAY
The ITWS screen depicts a weather system superimposed on a map, much like that of a TV weather forecaster. The storm itself looks like a colorful swirl on the screen, with highlighted areas of rain or wind shear. Blue lines show where the storm will be in the next 10-20 minutes. Yellow areas show where the line storm envelope will be 30 to 60 minutes in the future.
While an overview shows a radius of more than 100 miles, controllers can zoom down to an area as small as a city block if they want to check a specific region or runway. With the click of a mouse, more precise information, such as the presence of hail or lightning at that spot, is available.
Unlike the National Weather Service's NEXRAD reports, which change every six minutes, the ITWS system updates continually and smoothly. It also predicts microbursts -- sudden, violent downdrafts of air -- that are especially hazardous to airplanes during landing or takeoff.
SURPRISING COST SAVINGS
Dr. Evans, who heads the New York aviation weather research project at Lincoln Laboratory, said he was surprised by the magnitude of the savings ITWS achieved in New York in relationship to savings previously achieved with ITWS experiments in Memphis, Dallas and Orlando.
"Based on our previous experience, we had anticipated that the delay reduction at New York would be approximately $50 million per year," he said.
"We have achieved much higher-than-expected delay reductions here ($150 million) due to the use of a new, more advanced weather forecast product. And, due to the special nature of the New York airports, the very high traffic load into the New York airspace means that the operations are very different from airports such as Dallas, Memphis and Orlando," he said.
"A number of the ways that delays are reduced at those airports with an ITWS cannot be accomplished at New York due to the high degree of airspace congestion. On the other hand, the high degree of congestion at the New York airports results in high delay reductions from products such as better wind information, which is not very important at the less congested airports," Dr. Evans said.
A critical factor in the overall success of the NY-NJ area ITWS experiment has been the FAA air traffic personnel that have used the system, he said. "They are wonderful to work with, very interested in making the New York airports work better, and have developed many innovative uses of the products we provide," Evans said.
HOMING IN ON DELAY CAUSES
With Port Authority funding, the MIT researchers compiled detailed weather data with the ITWS and held daily discussions with FAA users of the system. This resulted in more detailed information about causes of delays than appear in the current FAA delay database.
In many cases, FAA delay databases did not capture specific information about how weather affected the days' arrival and departure times, the researchers noted.
Because FAA databases rely on direct observations of the weather, thunderstorms are reported only if they occur within seven miles of the airport. Many thunderstorm delays are generated by thunderstorms that occur farther away. Similarly, high winds in fair weather are not typically treated as delay causes in the database.
The MIT study found that both near and distant thunderstorms caused approximately 40 percent of arrival delays at Newark International Airport between 1998 and 2000. Low ceiling/visibility conditions were related to 27 percent of Newark delays, while high winds in fair conditions resulted in 16 percent of all arrival delays there.
Case studies in the report show that many of the delays could be avoided if the ITWS were extended to provide predictions of thunderstorm decay and predictions of the onset and ending of low ceilings or high surface winds.
Information on the MIT experimental New York ITWS system and the Terminal Convective Weather Forecast is available at http://www.ll.mit.edu/AviationWeather/.
The MIT research that provided the basis for the New York ITWS/TCWF demonstration system was funded by the FAA ITWS and Aviation Weather Research Programs. Information on the FAA ITWS program is available at http://www.faa.gov/aua/ipt_prod/weather/itws/.
A version of this article appeared in MIT Tech Talk on February 28, 2001.