When I visit a NASA center, there are posters up all over saying "If it's not safe, say so." Part of the reason for the 2-year grounding of the Shuttle fleet, post-Challenger, was to put in place a stronger culture of safety at NASA.
A commenter mentioned the false dichotomy of "engineers vs. managers". It's a hard call, as an engineer, to disappoint a manager (or a whole line of managers, all the way up) with a call to solve a possible problem. Civil engineers may be more used to this sort of accountability.