Frequent fliers are familiar with the ripple effect that weather in faraway places can have on their travels: thunderstorms that ground a flight in New York, for example, might cause a flight from Boston to Washington, DC, to be canceled, because it was scheduled to use the same airplane.

A tool developed by MIT Lincoln Laboratory's Weather Sensing Group, now in use in the New York area, has the potential to reduce those delays significantly.

The route availability planning tool (RAPT) provides pertinent information to air traffic managers and airline dispatchers during thunderstorms and other times of "convective weather," which is characterized by a lot of updrafts and downdrafts. The tool correlates the weather forecast with the departure trajectories of planes about to take off. "It identifies when departing flights will encounter weather that pilots would rather avoid," says Richard DeLaura, one of the system's developers. "Users can see where the predicted departure trajectories and the predicted weather will run into each other. Then they can make a more informed judgment about what they think they should do." RAPT could help find an opportune moment for that plane stuck in New York to leave for Boston, minimizing delays for the DC-bound passengers.

When Lincoln Lab began developing the tool, existing models suggested that in the New York area, being able to send out two or three more planes per airport per hour could reduce delays by 30 percent. DeLaura and his team completed a prototype of their system in 2003. Initially funded by the Port Authority of New York and New Jersey, RAPT is used by air traffic managers at Newark, JFK, LaGuardia, and Teterboro Airport in New Jersey, as well as by managers in the radar control facility that coördinates traffic in and out of New York-area airports. Neighboring air traffic control centers have access to the system, too, as do several commercial dispatch officers. The Federal Aviation Administration, which picked up funding for RAPT in 2007, is evaluating whether to deploy the tool in additional sites.