Microburst

Microburst

James Linson

Embry-Riddle Aeronautical University

One deadly weather phenomenon is microburst. Microbursts can quickly bring down an aircraft, most notably known incident Delta Flight 191 in Dallas, TX. August 1985. As one of the worst disasters contributed to microburst, this incident quickened the motion for research on how to avoid microbursts. Microbursts are columns of air that are localized and create a mixture of straight line and divergent downdrafts near the surface. They usually last from a few seconds to several seconds but they have immense power and can bring down an aircraft and make it crash. In the microburst, air rushes to the ground from the top in a downward directed funnel and then spreads outwards at the surface. Just the opposite of a tornado. In the Delta FLT 191 incident, a DC-10, a B727 and a Learjet all flew through the same cell before FLT 191, an L-1011, and reported slight to moderate turbulence. FLT 191 came through the cell and unfortunately was pushed into the ground.

In a microburst the air meets an oncoming aircraft with strong head winds. The aircraft would rise above the desired altitude. The pilot would decrease speed to get the aircraft to descend back to that altitude. As the aircraft comes out the opposite side, it now has a strong tail wind and is push down below the desired altitude. The pilot would now increase speed by advancing the throttles for the engines. The engines take a few seconds to spool up to produce the needed thrust. In the few seconds for the engines to deliver the thrust, the microburst’s down drafts are pushing the aircraft into the ground. Today’s technologies now have warning devices to help pilots steer aircraft away from microbursts.