the fundamental problem
"… the fundamental problem, that is, LOSS OF SITUATIONAL AWARENESS."
If something has been lost by the crew (apparently both simultaneously), then what is this 'awareness' which existed beforehand, how was it gained, maintained, and then why was it lost.
The fundamental problem is human nature, our limited ability to comprehend everything - a necessary limitation to function normally; but most of all our view with hindsight, and recognition of this bias.