The US National Transportation Safety Board found that Titan operator OceanGate did not adequately test the submersible and was unaware that it was damaged.
Archived version: https://archive.is/newest/https://www.dw.com/en/titan-sub-imploded-due-to-engineering-flaws-ntsb-report/a-74376583
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How has the NTSB weathered the current regime?
They haven’t found a way to politicize accident investigation yet.
I hope they can outlast this. Nothing but respect for people who deal with tragedies to try and prevent them from happening again.