IUMI's "Fixed-First" Approach — What It Means on the Bridge
The 2025 IUMI best-practice update made the priority order explicit: activate fixed systems before any manual intervention. The reasoning is sharper than most operators have absorbed.
IUMI's September 2025 update to "Risk mitigation for the safe ocean and short-sea carriage of electric vehicles" is short on rhetoric and long on order-of-operations. The headline is the "Fixed First" approach: activate fixed firefighting systems promptly before any manual intervention. The rationale walks through the casualty record.
Why the order matters
- Manual entry to a vehicle deck during a Li-ion event puts crew within reach of toxic gas exposure (HF in particular) within minutes.
- CO2 flooding is only effective if the deck is sealed before crew enter — Felicity Ace demonstrated the failure mode of doing it the other way.
- Time spent locating the fire manually is time the fixed system is not running.
What it implies for the detection layer
Fixed-First only works if detection produces a trustworthy red state. A bridge that hesitates to seal a deck because the alarm has cried wolf before is back to the Felicity Ace failure mode in a different costume. The detection layer is upstream of the IUMI recommendation working in practice.
Sources
- IUMI — "Risk mitigation for the safe ocean and short-sea carriage of electric vehicles" (Sept 2025 revision).
- Larsson, F. et al. — "Toxic fluoride gas emissions from lithium-ion battery fires," Scientific Reports 7, 10018 (2017).
- IMO MSC.1/Circ.1638 — "Recommended actions to address risks of fires on ro-ro cargo spaces and special category spaces" (2021).
- IMO — FSS Code Chapter 5, Fixed Gas Fire-Extinguishing Systems.
- [VERIFY: Felicity Ace primary investigative jurisdiction is Panama Maritime Authority; NTSB involvement was via USCG-coordinated channels, not a primary NTSB report.]
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