alt Hacker News1 out of the 12 crewed Apollo missions resulted in the death of the crew, so a 1 in 12 effective mortality rate.
Apollo 13 was a very close call. If that had ended in failure the mortality rate would have been 1 in 6.
So 1 in 30 would be a pretty clear improvement from Apollo, and we are a lot better and more thorough at modeling those risks and testing systems than we were during the Apollo program.
Is 12 enough of a sample size to make a statistical judgement? What if there were 20 more which didn’t have a loss of life? Is it then 1/30? What if there were 20 more?
The risk factor is calculated _per mission_ from what I understand. You can have three accidents in a row and nothing for decades but the risk itself can still be 1 in 30.