My older brother(RIP), was a Crew Chief (F-86)at McDill in the 50s when a LT., found out the hard way the Ejection Seats weren’t that kind.
Wasn’t his plane!
There was a large red X painted on the ceiling at NAS Jacksonville. Story was an electrician made a mistake and caused the seat to eject and it smashed the guy into the ceiling and killed him. Don’t know if this really happened or it was just a story to scare the students.