Mastering the microburst; these elusive winds drop from clouds and sweep planes out of the sky, but scientists are developing systems to detect them

Science News, March 21, 1987 by Richard Monastersky

Ground-based Doppler radar willbe reaching some airports in the near future. In 1989 the FAA plans to begin deployment of 16 Doppler radars at critical airports such as Dallas-Ft. Worth, Atlanta, O'Hare, Kennedy/La Guardia, Washington National, Miami/Ft. Lauderdale and Denver.

In the meantime, the FAA and airlinesare seeking to arm pilots with both the knowledge and skill to handle a micro-burst, in the event of an encounter. In February, a consortium of airplane manufacturers completed the framework for a pilot-training program involving meteorologic training and simulated micro-burst encounters. The FAA plans to require this training for all U.S. air carrier pilots, and implementation of the program should take a year or so. "When that gets transferred to the pilots, then I think we're going to be in a lot better shape,' says McCarthy, who advised the consortium.

"I don't think we're going to eliminatewind shear accidents,' says McCarthy, "but I think we're going to make them a 20- to 30-year phenomenon instead of a one- to two-year phenomenon.'

Photo: Cross section of a computer model of a microburst color-coded for temperature, with blue representing the coldest air. As outflow spreads horizontally, vortices of wind develop at the edge. Normally circular, these vortices are distorted by the scale.

Photo: Vertical cross section of the two-microburstsystem on the cover. Red arrows represent wind speed (length of arrow) and direction.

Photo: Doppler radar signature of a microburst.Green represents airflow toward the radar, and brown represents airflow away from the radar. Proximity of these two regions indicates hazardous wind shear.

Photo: When flying through a microburst, a plane on takeoff experiences a dangerously rapid loss of lift as it moves from headwind (1, 2) to tailwind (4, 5).

Photo: In the high plains near Denver, shown here, the precipitation associated with the downdraft often evaporates before the downdraft hits the ground. In such cases, a ring of spreading dust is sometimes the only clue that a microburst exists.

Photo: A circular vortex roll of dust marks theedge of an evolving microburst.