The first version of the Shuttle flight software had two serious problems: it couldn’t fit in the computer, and it ran way too slow. IBM was two years into the contract and basically nothing worked. All hell broke loose.
Hearing about the near-legendary competence of NASA astronauts was one thing, seeing it in action was humbling. Bob Crippen and Dick Truly, the two I got to work with on Space Shuttle, were the most impressive professionals I’ve met.