How the RCA investigation would read if I were on the team:
Incident : Deepwater Horizon Burns and Sinks
Why: The well blew out
Why: The drilling mud was displaced with seawater
Why: The signs of failed well components were ignored
Why: Failure in the chain of command, BP wellsite leader overriding rig leadership
Root cause: Management failure to support offshore personnel with respect to TOFS (time out for safety) Safety culture breakdown up to and including division management.
See MMS perspective: