Decision Simulator

Scot Stuttgart — The Checklist Said Isolated

Scot Stuttgart
Chemical Tanker · Puerto Nuevo Terminals, San Juan, Puerto Rico · 17 May 2025
Source: NTSB MIR-26-29

4Decision Points 3Possible Outcomes —Avg. Play Time

The Situation

You're the second engineer aboard a chemical tanker, preparing a lockout/tagout permit for scheduled maintenance on the port auxiliary generator — cleaning the turbocharger, aftercooler, and checking valves and injectors. The permit checklist asks you to consult the vessel's fuel piping drawings and identify every valve or circuit needing isolation.

The Lesson

Treat a checklist item as a starting point for verification, not proof it happened — and once a fixed suppression system is activated, follow its designed release quantity and sealed duration exactly, not a discretionary partial version of it.

Human Element

A fuel return line with no check valve, a maintenance checklist marked complete without the drawing review actually happening, and a partial CO2 release followed by an early re-entry — two separate decisions, hours apart, that each independently made the outcome worse.

Try the First Decision

You're completing the lockout/tagout permit for the port auxiliary generator maintenance. The checklist asks you to check the vessel's fuel piping drawings to identify every valve or circuit needing isolation before the aftercooler and fuel return tubing are removed. Do you actually trace the fuel return line on the drawings to its connection point, or sign off based on your general knowledge of the system?

A. Trace the fuel return line on the drawings specifically — confirm where it connects, whether it has a check valve, and whether it needs a temporary cap or isolation once disconnected.
B. Sign off from general knowledge of the system — you've done this maintenance before and the return line has never been an issue.

This is a preview — the full scenario branches from here based on what you choose, with real consequences and a debrief at the end.

Play the Full Scenario — Free

Create a free profile to play this scenario through to the end, with a full human-factors debrief. No card required.

Create Free Profile & Play →