There's this tweet from Wayne Hale, former NASA Flight Director
Several media people have asked me about how risky STS-1 was. There were a lot of uninformed guesses circulating in 1981. Thirty years later, based on everything we knew, we back calculated the probability of loss of crew and vehicle to be 1 in 9. That is pretty risky.
Why would the loss factor be estimated to be so high? Is there any methodology or report he was referring to here?
