On 2 August 1985, Delta Air Lines flight 191 crashed on approach to Dallas/Fort Worth, killing 136 people including one on the ground. The Lockheed L-1011 flew into a microburst — a small, intense column of descending air produced by a thunderstorm cell, which at the time was barely understood and not detectable by anything at the airport.
What a microburst does to an aircraft
A microburst is a downdraft that hits the ground and spreads outward. An aircraft flying into one first meets a strong headwind, which increases lift and airspeed — the aircraft rises and appears to be performing well. Seconds later it passes through the core and into the outflow on the far side, where the headwind becomes a tailwind. Airspeed collapses, lift is lost, and the aircraft is now low, slow and sinking.
The trap is the first part. The instinctive response to the initial gain in airspeed is to reduce power to stay on profile — which is precisely the wrong thing to have done thirty seconds later.
Delta 191 encountered this at low altitude on final approach, with no altitude to trade and no time.
Why nobody saw it coming
The storm cell was small and isolated, sitting near the approach path. Conventional weather radar at the time was designed to show precipitation, not wind shear, and a microburst can occur in a cell that does not look severe. Aircraft ahead of Delta 191 had passed through the same area without difficulty, which is characteristic — microbursts are brief and highly localised, and conditions can change entirely within minutes.
What changed
Delta 191 came after several similar accidents, and it was the one that produced action at scale.
- Terminal Doppler Weather Radar was developed and installed at major US airports specifically to detect wind shear and microbursts in the approach and departure corridors, and to alert controllers automatically.
- Low-level wind shear alert systems using ground anemometer networks were expanded.
- Onboard predictive wind shear detection became standard on transport aircraft, using the aircraft's own weather radar to look for the wind pattern ahead.
- Escape manoeuvre training was standardised: full power, target pitch attitude, accept the stick shaker, do not chase airspeed. Microburst recovery is now a recurrent simulator item.
The research effort behind this was substantial — a multi-year programme of instrumented flights into storms to characterise the phenomenon well enough to design detection for it. The meteorologist Ted Fujita, better known for the tornado scale, did much of the foundational work identifying microbursts as a distinct phenomenon.
Wind shear accidents on approach, once a recurring category, have become rare in airspace with this equipment. It is one of the clearer cases in aviation where a specific accident led to a specific technology that removed the hazard.