American Airlines Flight 191 crashed on May 25, 1979. All of the 271 people aboard died, as did two more on the ground. The cause: an improperly repaired engine mount that gave out under pressure, smashed a wing of the plane, and severed the hydraulic lines. The loss of hydraulic pressure led to slats on the wing retracting. The DC-10 went into a left roll and crashed. Investigators called it a 10 billion-to-one chance.

The event remains the greatest loss of life in American aviation history after the September 11 attacks. Though a disaster of such magnitude inevitably sears itself into private and public memory, the Flight 191 crash became even more memorable because a traveler at O’Hare Airport named Michael Laughlin captured a chilling image of the plane rolling over and another of the explosion that followed. The Chicago Tribune bought the photos for $500. They instantly became an indelible part of city history.

Observers at the time and after noted that the disaster might easily have been worse. The huge area of wreckage stopped about near a mobile home park and about 500 yards from a cluster of oil tanks belonging to Standard Oil.

The crash occurred during a spate of high profile late Seventies air disasters that included the Tenerife runway collision in 1977, to say nothing of the numerous hijackings that roiled aviation during that era. Flight 191 added to an overall atmosphere of uneasiness related to flying.

At the same time, the McDonnell-Douglas DC-10 faced even greater scrutiny. Trouble had dogged the plane almost since its debut in 1970, in particular a problem with cargo doors that led to a horrific crash of a Turkish Airlines flight outside Paris five years before Flight 191. For a time the DC-10 looked finished. The U.S. government grounded the entire fleet of them and banned the plane from U.S. airspace. American Airlines, meanwhile, received a $500,000 fine for using an unapproved maintenance shortcut prior to the disaster.