What is a microburst and why is it particularly hazardous to aviation?

Why →A microburst is a small but intense downdraft that spreads horizontally on reaching the surface, producing a sudden headwind-to-tailwind shift directly beneath it. Typical scale: 1–2 miles across, 5–15 minutes of life, downdrafts past 6,000 fpm. The sudden performance loss at low altitude may be unrecoverable.

The trap →A rotating column reaching the surface is a tornado, not a microburst. Microbursts are purely vertical collapse with horizontal outflow, no rotation. Cold front turbulence bands last hours; microbursts are short-lived and highly localized.

Field note →Microbursts can occur with virga (precipitation that evaporates before hitting the ground) as the only visual cue. If you see a towering cumulus or cumulonimbus building overhead, land immediately. Do not wait for rain to start.