Is Individually Identifiable Detection Required?

It depends on which ship you are asking about, and the answer is older than 2026. "Individually identifiable" is a defined term in Chapter 9 of the FSS Code, and passenger ships have been required to meet it for every fixed detection system since 1 July 2012. What Resolution MSC.550(108) did on 1 January 2026 was restate that requirement for the vehicle and ro-ro spaces of new passenger ships and attach smoke-and-heat coverage to it. A cargo ship — which is what a car carrier is — was left where the FSS Code has always left it: section identification as a minimum. The earlier version of this post said the opposite, and this version is read from the resolution and the Code.

What the FSS Code means by the term

A system that can say which device, not which group. Chapter 9 paragraph 1.2.3, as adopted by MSC.311(88), defines individually identifiable as "a system with the capability to identify the exact location and type of detector or manually activated call point which has activated, and which can differentiate the signal of that device from all others". The alternative is defined one line above it: section identification capability is "a system with the capability of identifying the section in which a detector or manually operated call point has activated", where a section is simply a group of detectors and call points as reported at the indicating unit.

Paragraph 2.1.7 then allocates the two capabilities by ship type. In passenger ships, the fixed fire detection and fire alarm system shall be capable of remotely and individually identifying each detector and manually operated call point. In cargo ships, and on passenger-ship cabin balconies, the system shall as a minimum have section identification capability. Paragraph 2.5.1.3 repeats the split at the bridge: a passenger ship must have an indicating unit on the navigation bridge that individually identifies the activated detector; a cargo ship's indicating units shall, as a minimum, denote the section. That has been the position for every ship constructed on or after 1 July 2012.

What MSC.550(108) actually changed

For new passenger ships, it made the capability explicit for vehicle decks and paired it with coverage. Paragraph 20.4.1.1, applying to passenger ships constructed on or after 1 January 2026, requires an individually identifiable fixed fire detection and fire alarm system in vehicle, special category and ro-ro spaces, providing smoke and heat detection throughout, with linear heat detection acceptable to the Administration in place of point heat detectors, capable of rapidly detecting the onset of fire, and tested after installation under normal ventilation for an overall response time. Paragraph 20.4.1.2 requires that where a deluge system is fitted, the detection sections be identifiable to the same sections as the deluge. Paragraph 20.4.1.3 requires an interface that presents the information logically and unambiguously, with section numbering that coincides with the drencher and the video system.

For existing passenger ships, the retroactive paragraph is 20.4.1.6, due at the first survey on or after 1 January 2028: smoke and heat detection throughout, with heat detectors at smoke-detector spacing wherever a smoke detector already exists. It does not use the words individually identifiable — a ship constructed before July 2012 whose system reports by section is required to add heat detection, not to change its reporting resolution. For cargo ships constructed on or after 1 January 2026, the whole of the change is paragraph 20.4.1.5: a fixed detection system complying with the FSS Code, capable of rapidly detecting the onset of fire, tested under normal ventilation. Complying with the FSS Code, for a cargo ship, means paragraph 2.1.7 — section identification as a minimum. Cargo ships constructed before 2026 comply with the previously applicable text.

What the definition demands of a system

More than an address per detector. The definition's second clause — the system "can differentiate the signal of that device from all others" — is a statement about the loop, not the head, and paragraph 2.1.6 spells out what it requires of an individually identifiable installation. A fault in the section — a power break, a short circuit, an earth — must not prevent the continued individual identification of the remaining detectors on it. Arrangements must exist to restore the initial configuration after an electrical, electronic or software failure. The first alarm must not prevent any other detector from raising a further alarm. No section may pass through a space twice, and where that is unavoidable in a large space the second pass must be run at the maximum possible distance from the first. Paragraph 2.4.3.2 adds the fire-survivability rule: an individually identifiable section shall be arranged so that it cannot be damaged at more than one point by a fire.

Those four conditions are what separate a genuinely addressable deck from a zone system with addresses bolted on. A loop that loses every downstream head when one cable is cut by the fire it is meant to report satisfies the definition on the bench and fails it on the deck. The design consequences are cable routing that keeps the two ends of a section apart, isolation at each device so a short is confined, a controller that keeps reporting the survivors, and a stored configuration that can be reloaded. A system built from individually addressed points with per-node isolation meets the definition natively; the harder retrofit is the legacy loop that has to be re-cabled to survive a single fire.

The section rules also shape how a car deck can be wired. A section covering a ro-ro space may not include a machinery space of category A; on a passenger ship no section may span more than one main vertical zone; and where a system is not individually identifiable, the number of enclosed spaces per section is capped by the Administration "in order to avoid delay in identifying the source of fire" — the Code's own statement of why the distinction exists. The 2026 amendment adds one more constraint for new passenger ships: the detection section must map onto the drencher section, so the number the bridge sees is the valve the crew opens.

Why section identification is still lawful on a car carrier

Because nobody has yet written the rule that changes it. The FSS Code's cargo-ship minimum was set with accommodation and machinery spaces in mind, where a section is a corridor or a compartment. On a PCTC a section can be a vehicle deck holding several hundred cars, and the delay the Code warns about in 2.4.1.3 is exactly the delay the ro-pax casualties produced — a crew told a deck, searching for a vehicle. The Pearl of Scandinavia crew in 2010 doused the wrong side of a bulkhead for ten minutes on a zone alarm; the 2026 amendment closes that gap on passenger ships and leaves it open on cargo ships.

The IMO work that could close it is the new-energy-vehicle output. At SSE 12 in March 2026 the Sub-Committee chose to draft interim guidelines first — on fire safety measures for pure car and truck carriers, and on video monitoring and detection systems — with a correspondence group reporting to SSE 13 in March 2027 and a SOLAS amendment entering into force on 1 January 2032 at the earliest. The ro-pax text is the obvious template: individually identifiable smoke-and-heat detection with sections matched to suppression is what the IMO has already decided a vehicle deck needs when there are passengers above it. Whether that transfers to a deck with no passengers is the question the guidelines will answer.

What it means for owners and class

For a PCTC newbuild the specification has to carry the requirement, because SOLAS does not. The clean way to write it is by reference: individually identifiable to FSS Code Chapter 9 paragraph 1.2.3, arranged in accordance with 2.1.6 and 2.4.3.2, with an indicating unit on the bridge that identifies the device per 2.5.1.3 as for a passenger ship, and — borrowing 20.4.1.2 — detection sections identifiable to the drencher sections. Written that way, the class surveyor has a paragraph to survey against rather than a vendor's adjective. For an existing PCTC there is no statutory trigger: the 2028 date belongs to passenger ships, and any upgrade is a commercial or charterer-driven decision, which should be described as such in a safety case.

For a ro-pax owner the position is the reverse. A ship built after July 2012 already has individually identifiable detection everywhere it has detection; the 2026 and 2028 items are smoke-and-heat coverage, video, and — on a newbuild — the section-to-drencher mapping and the interface rules. A ship built before 2012 that still reports by section is required to add heat detection by 2028 but is not required by 20.4.1.6 to change its reporting resolution, and that is a point worth confirming with class rather than assuming either way.

Sources

• 1. IMO Resolution MSC.311(88), adopted 3 December 2010, in force 1 July 2012 — Amendments to the FSS Code, Chapter 9: 1.2.1 (section), 1.2.2 (section identification capability), 1.2.3 (individually identifiable — "exact location and type of detector … and which can differentiate the signal of that device from all others"); 2.1.6 (arrangement of individually identifiable systems — fault tolerance within a section, restoration of configuration, first alarm not blocking further alarms, no section through a space twice); 2.1.7 (passenger ships: remotely and individually identifying each detector; cargo ships and cabin balconies: section identification as a minimum); 2.4.1.2–2.4.1.4 (section composition; enclosed spaces per section limited "to avoid delay in identifying the source of fire"; one main vertical zone per section on passenger ships); 2.4.3.2 (section not damageable at more than one point by a fire); 2.5.1.1 (two-minute acknowledgement before general alarm); 2.5.1.3 (indicating units — individual identification on passenger-ship bridges, section as a minimum on cargo ships). Read from the resolution text.
• 2. IMO Resolution MSC.550(108), adopted 23 May 2024, in force 1 January 2026 — SOLAS II-2/20 as amended: 4.1 application text (4.1.1–4.1.4 passenger ships constructed on or after 1 January 2026; 4.1.5 cargo ships constructed on or after 1 January 2026; cargo ships constructed before that date comply with the previously applicable 4.1); 4.1.1 and 4.1.1.1 (individually identifiable system with smoke and heat throughout, linear heat acceptable, rapid onset, ventilation test); 4.1.2 (detection sections identifiable to deluge sections); 4.1.3 (interface, section numbering coinciding with fixed water-based and video systems); 4.1.6 (existing passenger ships — smoke and heat, heat at smoke spacing, first survey on or after 1 January 2028). Read from the resolution text.
• 3. IMO Resolution MSC.555(108) — Amendments to FSS Code Chapters 7 and 9, applying to ships constructed on or after 1 January 2026: combined smoke-and-heat and linear heat detector specifications; for ro-ro passenger ships, interface requirements for alarm addressability, alarm history and alarm suppression with ongoing alarms kept visible.
• 4. DNV — "IMO Sub-Committee on Ship Systems and Equipment (SSE 12)", March 2026: interim guidelines on fire safety measures for PCTCs and on video monitoring and detection systems to precede SOLAS amendments; correspondence group to SSE 13 (March 2027); entry into force 1 January 2032 at the earliest.