Experts raised safety concerns about the Titan submersible vessel in 2018. Will Kohnen wrote to missing OceanGate founder Stockton Rush outlining his concerns. Read the best of our journalism: https://www.thetimes.co.uk/ Subscribe to The Times and The Sunday Times YouTube channel: https://www.youtube.com/subscription_... Find us on Facebook: / timesandsundaytimes Find us on Twitter: / thetimes Find us on Instagram: / thetimes