On August 2, 1985, Delta Air Lines Flight 191 — a Lockheed L-1011 TriStar carrying 163 people — was on final approach to Dallas/Fort Worth International Airport. A thunderstorm cell sat north of the field. The crew saw lightning but pressed on. At roughly 800 feet above the ground, the aircraft entered a microburst. In the span of twenty seconds, the headwind component shifted from 26 knots to a 46-knot tailwind. The TriStar lost 54 knots of airspeed in moments. It struck the ground short of the runway, bounced across a highway, hit a car, and slammed into two water tanks. One hundred and thirty-seven people died. Delta 191 was not the first microburst accident. But it was the one that changed everything.

The Anatomy of a Microburst

A microburst begins as a downdraft inside a thunderstorm — a column of rain-cooled air plunging toward the ground at speeds that can exceed 6,000 feet per minute. When the column hits the surface, it spreads outward in all directions, creating a ring of violently diverging winds at ground level. An aircraft approaching through a microburst first encounters a strong headwind as it flies into the outflow. The headwind increases airspeed and lift — the aircraft balloons above the glidepath. The natural pilot response is to reduce power and lower the nose. Then, in seconds, the aircraft passes through the centre of the microburst and enters the downdraft and tailwind on the far side. Airspeed collapses. Lift disappears. The aircraft is now low, slow, in a descending column of air, with reduced power — exactly the wrong configuration for survival. The physics are merciless. The entire sequence — headwind to downdraft to tailwind — can unfold in less than thirty seconds. At 200 feet above the ground on final approach, thirty seconds is not enough time to recover.

Fujita’s Breakthrough

The man who identified and named the microburst was Dr. Tetsuya Theodore Fujita — the same meteorologist who created the Fujita tornado intensity scale. In the 1970s and early 1980s, Fujita studied a series of otherwise inexplicable approach accidents and hypothesised that small-scale downdrafts — too small to be detected by conventional weather radar — were responsible. His hypothesis was initially met with scepticism. Established meteorology held that downdrafts of the intensity Fujita described could not occur in such small areas. But field research — including the Joint Airport Weather Studies (JAWS) project in Colorado — confirmed his theory. Microbursts were real, common, and deadly. After Delta 191, Fujita’s work went from academic research to urgent national priority.

How Modern Jets Fight Back

The response to Delta 191 was comprehensive. The FAA mandated the installation of Terminal Doppler Weather Radar (TDWR) at major airports across the United States. TDWR can detect wind shear and microbursts in real time and automatically transmit alerts to controllers and pilots. Simultaneously, aircraft manufacturers developed onboard predictive windshear systems. Modern airliners carry forward-looking radar that can detect the signature of a microburst ahead of the aircraft — the rapid divergence of raindrops in the radar return — and alert the crew before they enter the shear. The cockpit warning is unambiguous: a red windshear icon and an automated voice call of “WINDSHEAR, WINDSHEAR, WINDSHEAR.” The escape manoeuvre is equally unambiguous: maximum thrust, pitch to 15 degrees nose-up, and fly through the shear without attempting to maintain altitude. Accept the altitude loss. Accept the overspeed or underspeed. Just keep flying. Since the widespread deployment of TDWR and onboard windshear systems in the 1990s, there has not been a single microburst-related fatal accident involving a major U.S. airline. It is one of aviation safety’s greatest victories — and it was bought with the lives of 137 people aboard a TriStar on a summer afternoon in Texas. Sources: NTSB, NASA, FAA, University of Chicago (Fujita Archive)