The turbulence is no worse being up high in the plane vs being down in a seat. In the 1950s, NONE of the passengers would have been using seatbelts...

“When an airplane crashes, the safety belt…may become a deadly hazard.”

- Scientific American Dec 1951 “The Dangerous Safety Belt”

"Aviation requirements for basic safety features, including passenger safety belts, were codified in 1972"

- https://www.smithsonianmag.com/air-space-magazine/how-airlin...

Concussions hadn't been invented yet, that's why no one wore a helmet back then