Faultory

Case file 66 · Engineering & technology

Readings from a hull under strain

Titan submersible, 2023: what did the hull’s own monitoring data show before the final dive?

Subject
Titan submersible implosion (2023)
Reading
14 min
Evidence
5 exhibits
Reasoning
3 steps
Level
Advanced
Coast Guard engineers survey a titanium end cap from the Titan submersible.
October 2023 Coast Guard marine safety engineers survey the aft titanium endcap from the Titan, working for the Marine Board of Investigation. Photo: Melissa Le, U.S. Coast Guard · Public domain · Wikimedia Commons.
Illustrative signature. An illustrative strain-like signal that rises linearly, bends after a point and then drops sharply, drawn to show the shape of a change rather than measured strain. Drawn to explain the case, not plotted from source data.

01 · The briefing

Begin with the question.

On 18 June 2023, the submersible Titan, operated by OceanGate, was descending toward the wreck of the Titanic about 370 nautical miles southeast of St. John’s, Newfoundland, when its pressure hull failed and it imploded. All five people on board died. The Titan’s pressure vessel was a carbon-fibre composite cylinder. The expedition dives in 2022 matter most here, because complete monitoring records for those dives survive. The vessel was not classed by a classification society, although the company had originally intended to class it. The vessel carried acoustic emission sensors and strain gauges that recorded data during dives, and the company processed that data after each dive. The two reports weigh the hull’s material and construction, the design and certification process, and the decisions made after earlier anomalies. This investigation asks what the monitoring data showed before the casualty dive, and whether the analysis of those data matched what they showed. The NTSB’s marine report and the US Coast Guard’s Marine Board of Investigation report both draw on the vessel’s history, so their agreements and disagreements can be checked against the evidence.

The timeline

  1. OceanGate begins developing the Titan’s pressure vessels. The original design goal was a rating to 6,000 metres, with a 2.25 safety factor and a 10,000-cycle life limit.

  2. Dive 75 begins the 2022 expedition dives for which complete acoustic and strain data survive.

  3. On dive 80, a ‘loud bang’ is heard inside and by the crew of a surface boat as the Titan ascends after reaching the wreck at 3,840 metres.

  4. Dive 83, the last dive of the 2022 expedition, is completed. The Titan made three dives after dive 80.

  5. The Titan implodes during dive 88 while diving to the Titanic wreck. All five people on board die.

  6. The US Coast Guard Marine Board of Investigation releases its report. As reported by CNN, the factors it identified included inadequate design and maintenance of the Titan and a toxic safety culture at the company.

  7. The NTSB releases its marine investigation report MIR-25-36, which names an inadequate engineering process as the probable cause.

A researched reconstruction for learning. These reasoning steps simplify a complex record; no score can capture the full history.

02 · The evidence

What does the record show?

Read each exhibit before settling on an explanation. The source links below every exhibit lead to the record behind it.

Exhibit 01

The probable cause and the monitoring data

The NTSB determined that the probable cause was OceanGate’s inadequate engineering process, which failed to establish the actual strength and durability of the pressure vessel. It found that the vessel sustained delamination after dive 80, and additional damage of unknown origin after dive 82, which led to local buckling. It also names OceanGate’s flawed analysis of its pressure vessel monitoring data as contributing, because it led the company to continue operating a damaged vessel. This establishes the board’s conclusions. It does not show exactly when the first delamination formed within dive 80.

Source record s1ntsb.gov

Exhibit 02

What the 2022 monitors recorded

OceanGate saved acoustic emission and strain gauge data for the 2022 dives it considered notable. Complete data exist for dives 75, 76 and 79 to 83. Three of the eight acoustic sensors recorded no events during any of the 2022 dives. The strain response was linear at all depths through dive 80, but on dives 81, 82 and 83 the response at low depth became non-linear, and changes appeared on other gauges as well. The data for the casualty dive could not be recovered. This establishes what the monitors recorded. The NTSB’s interpretation depends on its comparison of the plots, not on a direct measurement of the damage.

Source record s1ntsb.gov

Exhibit 03

A loud bang and a decision to dive again

The NTSB reports that on 15 July 2022, mission specialists inside the Titan and the crew of a small surface boat heard a ‘loud bang’ as the vessel ascended after reaching the wreck. According to a former mission specialist and crew, staff were told the hull had shifted in its cradle. After reviewing the strain and acoustic data, the chief executive is reported to have told the director of engineering, ‘Let’s dive again and see what happens.’ The Titan then completed three more dives. This establishes what the report records from those accounts. The statements come from witnesses cited by the NTSB and are presented as accounts, not proven facts.

Source record s1ntsb.gov

Exhibit 04

Certification outside the classification system

The NTSB reports that the Titan was never classed by a classification society, although OceanGate had originally intended to class it. It says that classification societies and the Coast Guard had no ‘experimental’ design endorsement for vessels carrying passengers, and that the Coast Guard’s approach to passenger submersibles required a level of safety equivalent to a surface craft of similar size. It also found that voluntary US and international guidance for pressure vessels for human occupancy was insufficient. This establishes the regulatory context. It does not establish that classification alone would have prevented the implosion.

Source record s1ntsb.gov

Exhibit 05

The Coast Guard board’s findings on the company

CNN’s live coverage of the Coast Guard Marine Board of Investigation report, released in August 2025, says the board found the hull’s design, construction and testing to be major factors, and described the company’s operational and safety practices as critically flawed and its culture as toxic. It reports that the board found OceanGate did not properly investigate hull damage from an incident in July 2022, and that decision-making rested with the chief executive while the engineering director post was left vacant. This establishes the board’s findings as reported. It is a news summary, not the report itself.

Source record s2edition.cnn.com

03 · Your reasoning

Follow the strongest explanation.

Choose an interpretation, then compare it with the evidence. You can revise your choice. The goal is understanding, not a perfect score.

Reasoning step 01 of 03

What did the 2022 monitoring data most clearly show before the final dive?

Evidence-based explanation

The NTSB’s comparison shows that the strain response was linear through dive 80 and changed afterwards, and that acoustic events were recorded on some channels. The NTSB identifies flawed analysis of this data as contributing to the decision to keep operating the vessel. The available 2022 data therefore pointed to a change that was not treated as a stop condition. The bang is reported by witnesses, while the monitoring data are recorded measurements, which is why the data are the primary evidence here.

Weigh it against

Exhibit 01The probable cause and the monitoring dataExhibit 02What the 2022 monitors recordedExhibit 03A loud bang and a decision to dive again

Reasoning step 02 of 03

Which explanation best accounts for the non-linear strain response on dives 81 to 83?

Evidence-based explanation

The strain response was linear through dive 80 at all depths and became non-linear afterwards, with changes on several gauges. The NTSB found that the cylinder likely sustained one or more delaminations after dive 80, and that further damage of unknown origin followed after dive 82. A change in how a damaged cylinder carries load is the reading that fits the sequence and the multiple gauges, which is why the NTSB links the later data to structural damage.

Weigh it against

Exhibit 01The probable cause and the monitoring dataExhibit 02What the 2022 monitors recorded

Reasoning step 03 of 03

Which practice would most directly have prevented continued operation after the dive-80 anomaly?

Evidence-based explanation

The NTSB recommends that the Coast Guard commission expert study of pressure vessels for human occupancy and implement regulations consistent with international requirements. Its probable cause includes the flawed analysis of monitoring data, which led to continued operation. Interpretation: an independent, documented analysis with a rule to stop diving would address that flawed analysis directly, although the NTSB does not prescribe one. More channels, experience alone or deeper dives do not address the analysis gap or the unverified strength of the hull.

Weigh it against

Exhibit 01The probable cause and the monitoring dataExhibit 02What the 2022 monitors recordedExhibit 04Certification outside the classification system

04 · The findings

The chain behind the outcome.

The Titan’s hull failed through a combination of structural weakness and continued operation. The NTSB found that OceanGate’s engineering process did not establish the actual strength and durability of the carbon-fibre pressure vessel, and that the vessel likely sustained delamination after dive 80 and further damage of unknown origin after dive 82. The recorded strain data show a change: the response was linear through dive 80 and became non-linear at low depth on dives 81 to 83, with changes on other gauges. Acoustic events were recorded on some channels, and a loud bang had been heard during the ascent of dive 80. The NTSB found that the company’s analysis of these data was flawed and led it to keep operating the vessel. As reported by CNN, the Coast Guard board described the design, construction and testing as major factors, called OceanGate’s operational and safety practices critically flawed and described its safety culture as toxic. The regulatory context was also weak: the Titan was not classed, and the guidance for pressure vessels for human occupancy was voluntary and insufficient. The vessel imploded on dive 88 on 18 June 2023, and all five people on board died. The established facts are the monitoring data, the reported bang and the decision to keep diving. The weight given to each contributing factor is the judgment of the two reports.

Contributing causes and conditions

  1. OceanGate’s engineering process did not establish the actual strength and durability of the carbon-fibre pressure vessel.
  2. Delamination formed after dive 80, and further damage of unknown origin followed after dive 82.
  3. Acoustic and strain changes were recorded on dives 80 to 83, but the company’s analysis did not treat them as a reason to stop.
  4. The vessel was not classed by a classification society, and guidance for pressure vessels for human occupancy was voluntary and insufficient.
  5. Decision-making was concentrated in the chief executive, and the engineering director post was left vacant, according to the Coast Guard board as reported.

OutcomeTitan submersible implosion (2023)

Take the method with you

  1. A monitoring system is only useful if someone is accountable for a documented interpretation of its data before the next use.
  2. An anomaly that is not understood is a reason to stop until an independent analysis explains it.
  3. Measured changes in a structure’s response should be compared with that structure’s own baseline, not only with a design target.

You can read findings at any time. Exploring every reasoning step marks this case as complete in your notebook.

Open another investigation

The open record

Sources & further reading

Read the original record and its scope before relying on a conclusion. Source references support the exhibit summaries; Faultory’s reasoning prompts are editorial reconstructions.

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Written and curated for Faultory by Yunus Emre Vurgun, with AI-assisted research and drafting. Sources and interpretations can need correction. Read our editorial standards or report an issue.

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