Let me give you a tragic example of where psychological safety wasn't present.
Eight days after witnessing ambiguous video footage,
an engineer named Rodney Rocha,
who was very deeply involved with the Columbia Shuttle at NASA in 2003,
witnessed what looked to him
like possibly a large piece of foam hitting the shuttle during launch.
He wasn't sure whether that was what he had seen,
but it was possible that is what he had seen.
Eight days into the mission,
there was a very large mission management team meeting.
Maybe 35 people in the team were present at the meeting,
and more senior people were discussing the problem,
and Rodney Rocha did not speak up with his concern.
When asked why by Charlie Gibson
in an ABC news interview,
why he didn't speak up.
He said, "I just couldn't do it."
"She," meaning senior manager, Linda Ham,
who was at least two organizational levels above Rocha,
"was way up here," gesturing with his hand over his head,
"and I was way down here," gesturing with his hand near his lap.
This is a tragic situation.
Here is a very smart,
very knowledgeable, very expert engineer,
not willing to speak up with a tentative concern in a management meeting
because he feels unsafe psychologically.
This lack of psychological safety, quite literally, led
to a tragic accident that killed seven astronauts eight days later.