Titan was fitted with two systems intended to monitor pressure hull integrity. What were they, and what was the key limitation identified by the TSB?

A. A strain monitoring system (analysed inconsistently post-dive, so it never triggered removal from service) and an acoustic emission monitoring system (untested for reliable advance warning, and it did not function as intended in the occurrence)

B. A sonar collision-avoidance system and a CO2 scrubber alarm, both of which had flat batteries on the day of the dive

C. A ballast-tank pressure sensor and a hull-temperature sensor, neither of which was rated for the operating depth

D. A GPS tracking beacon and a VHF distress transmitter, both of which lost signal below 50 metres

A. A sphere distributes external hydrostatic pressure evenly across its surface, avoiding stress concentrations

B. A sphere is cheaper to manufacture from carbon fibre

C. A cylindrical hull cannot be pressure-tested before sea trials

D. A sphere allows a higher passenger capacity for the same hull weight

A. They were never validated to confirm they matched the theoretical values used in the original design

B. They exceeded design specification and provided an additional safety margin

C. They were validated by an independent classification society prior to first dive

D. They matched design values but degraded only after the fifth dive