Running from the mountain and running from the eruption were two different directions.
Every escape from Pompeii started with the same instinct: away from the mountain. But the eruption was not the mountain — it was the column above the mountain, thirty kilometers tall, and the high-altitude wind was pushing it southeast, over Pompeii and far down the coast beyond. That geometry sorted the refugees. Heading south, the intuitive direction, meant walking with the fallout: hours under the same rain of stone the city was drowning in, on roads growing softer and deeper with pumice. Heading north meant a well-maintained road toward Naples and, crucially, edges — the fallout zone thinned and ended in that direction. Written records of survivors cluster in the towns north and northwest; the remains of those who attempted escape too late have been found predominantly to the south.
None of this was knowable from street level in the dark. Wind direction at thirty kilometers' altitude is not something a person under a stone sky can read, and no one alive had seen an eruption column before. The people who chose south simply applied the only map anyone had — distance from the visible threat — to a hazard that worked on a different axis.
The most documented wrong-direction journey of the day belongs to Pliny the Elder (see: Record 02). Blocked from his planned rescue landing, he diverted south to Stabiae — deeper into the fallout corridor. The same onshore wind that had sped him in pinned every ship to the beach, and the pumice kept falling through the night. He died there at dawn, on the far edge of a fallout zone that a northbound course would have exited. His nephew, at Misenum to the northwest, lived to write it all down.
The modern escape from Pompeii happened in California in November 2018, and it has a federal case study. When the Camp Fire reached the town of Paradise, the evacuation sent roughly 40,000 people onto a road network that the fire was closing in real time. The National Institute of Standards and Technology later reconstructed the morning and found that for most of it, two or more of the town's four exit routes were cut off at any given moment. Think about what that means from inside a car: the map in every resident's head said Paradise has four ways out, and for hours at a stretch that map was simply wrong — but nobody in the smoke had any way to know which two roads were currently the real ones. Drives that normally took twenty-five minutes took hours, when they moved at all; some people were overrun by the fire in gridlocked traffic, inside vehicles that had been the obvious means of escape. Eighty-five people died. The underlying problem is Pompeii's, restated: in a moving disaster, “away” is not a fixed direction. The safe route is being decided minute by minute by physics you cannot see from ground level — wind at altitude, the drift of a plume, the speed of a fire front — so the intuitive answer, distance from the visible threat, keeps pointing at roads the disaster has already claimed. NIST's guidance to fire-country towns since then amounts to the lesson Campania paid for in 79 AD: the only version of the escape map you can trust is the one you studied before the sky changed color.
“Away from the mountain” is a direction. So is “downwind.” That day they were the same one.