Sustainability was a hot topic this week at the Paris Air Show, the world’s largest event for the aviation industry, which faces increasing pressure to reduce the climate-changing greenhouse gases that aircraft spew.

In the wake of the Titan’s fatal implosion near the Titanic shipwreck on Sunday, some people who embarked on the company’s deep-sea expeditions described experiences that foreshadowed the tragedy and look back on their decision to dive as ‘a bit naïve.’

The train crew was safe and no injuries were reported after the collapse in Montana, officials say.