The catastrophic loss of OceanGate’s Titan submersible with all hands aboard has triggered widespread speculation regarding the cause of the accident. Inadequate design, insufficient testing and the use of carbon fiber as a structural material have all been suggested as contributing factors. Carbon fiber is a well-characterized material that is strong and light, making it a favourite for weight-critical applications in aerospace. Its use in the much less weight-sensitive application of subsea exploration may have more to do with the way composite pressure vessels are built, rather than weight or performance. * * *Want to watch this podcast as a video? This Week in Engineering is available on engineering.com TV along with all of our other shows such as End of the Line, Designing the Future, Manufacturing the Future, and the Engineering Roundtable.