Enclosed Space Entry
The seemingly simplest operation that continues to cause fatalities on board: why the drill mandatory every two months since 2015 exists, and how to make it genuinely useful.
Operational Explanation
Confined spaces (cargo holds, tanks, cofferdams, double-bottom spaces) present a specific and recurring risk: an atmosphere deficient in oxygen or containing toxic/flammable gases, often not detectable without instrumentation, even in spaces that appear ventilated or have already been inspected previously.
Fatal accidents in confined spaces frequently follow the same pattern: a first victim enters without checking the atmosphere, a second crew member enters to rescue them without adequate protection, increasing the number of casualties. This is why the periodic drill focuses as much on prevention as on the correct rescue procedure.
Regulatory Reference
SOLAS Chapter III, Regulations 19.3.3 and 19.3.6 (in force since 1 January 2015, res. MSC.350(92)). They are two distinct paragraphs and it pays to keep them apart: 19.3.3 sets who and how often — “Crew members with enclosed space entry or rescue responsibilities shall participate in an enclosed space entry and rescue drill to be held on board the ship at least once every two months”, so personnel with entry or rescue responsibilities, not the whole crew — while 19.3.6 sets how: the drill must be planned and conducted safely, and must cover the use of PPE, atmosphere-testing instruments, communication and rescue equipment, and basic first aid.
Regulation XI-1/7, adopted by resolution MSC.380(94) and in force since 1 July 2016, adds the material obligation that makes the drill of regulations III/19.3.3 and 19.3.6 practicable: every ship must carry “an appropriate atmosphere testing instrument or instruments for enclosed space entry” capable of measuring, as a minimum, oxygen, flammable gases or vapours, carbon monoxide and hydrogen sulphide. It is not personal protective equipment but part of the ship's safety equipment: it must be calibrated by appropriate means and is a surveyable item (Cargo Ship Safety Construction or Passenger Ship Safety). Guidance on selecting the instrument is in MSC.1/Circ.1477.
2025 update. Resolution MSC.581(110), Revised Recommendations for Entering Enclosed Spaces Aboard Ships, adopted on 27 June 2025, adopted revised recommendations and invited the IMO Assembly to revoke A.1050(27), which was the previous recommendatory reference: the invitation is in its paragraph 3, and the formal revocation is not identified as adopted. They remain recommendations, not binding rules — the text says so itself — but they are the yardstick by which the PSCO and the auditor measure the adequacy of SMS procedures, and they introduce three new elements many ships do not yet have: a ship-specific enclosed spaces register listing all enclosed spaces together with their connected and adjacent spaces, their hazards and the associated risk mitigations; an enclosed space emergency response plan “easily understood, regularly practised, verified as effective and followed precisely”; and explicit reference values for atmosphere testing: oxygen at 20.9%, carbon dioxide below 0.5% by volume (5,000 ppm), flammable gases below 1% of the lower flammable limit, toxic vapours below 50% of the occupational exposure limit. The carbon dioxide threshold is the operational novelty: it requires an instrument that measures it, and XI-1/7 does not list it among the four mandatory gases.
Scope of Application
Every ship with spaces classifiable as confined (cargo holds, tanks, double-bottom cofferdams, pump rooms), for all personnel involved in entries or rescue operations.
Procedure / How to Complete It
- Never enter a confined space without a formal authorisation (permit to work) and a prior atmosphere check.
- Test the atmosphere with calibrated instruments (oxygen, flammable gases, toxic gases) before entry and periodically throughout the time spent inside.
- Ensure adequate ventilation of the space before and during entry.
- Keep an outside attendant in constant communication with those inside.
- Conduct the enclosed space entry and rescue drill at least every 2 months, with participation of all personnel involved.
- In an emergency, never enter to rescue someone without breathing apparatus and support, to avoid adding further casualties.
Practical Example
Example drill: simulation of a crew member falling ill inside a double-bottom cofferdam, with recovery using a harness and tripod, use of breathing apparatus by the rescue team, and verification of communication with the outside throughout the operation.
What Typically Goes Wrong
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Entry without instrumental verification of the atmosphere, relying only on the visual appearance of the space | An oxygen-deficient or toxic atmosphere goes undetected, a mortal risk | Always test the atmosphere with calibrated instruments before every entry, without exception |
| Immediate rescue attempt without breathing apparatus when the person inside falls ill | The rescuer becomes a second victim | Train the crew never to enter to rescue without adequate protection, even in an emergency |
| Two-monthly drill skipped or reduced to mere theory without practical exercise | The crew fails to gain real familiarity with using the equipment in an emergency | Always conduct the drill with hands-on use of PPE, instruments and rescue equipment |
What the PSCO Checks
Operational Tips
- Never make exceptions to the instrumental atmosphere check, even for spaces considered 'safe' based on past experience.
- Constantly repeat the most important rule to the crew: never rescue without breathing apparatus.
- Use the every two months drill as a genuine practical test, not as a theoretical formality.
Preparation checklist
Educational checklist. This summary supports learning and preparation only. It does not replace the vessel’s approved procedures, manuals, statutory documents, company SMS, or applicable official requirements. Completing it demonstrates neither compliance nor readiness for an inspection: it shows that a list has been read, not that the ship is in order. Always verify the current documents carried on board.
- Formal permit to work issued before every entry
- Atmosphere tested instrumentally before and during the time spent inside
- Adequate ventilation ensured before and during entry
- Outside attendant present and in constant communication
- Entry and rescue drill conducted at least every 2 months
- Atmosphere testing instrument on board and calibrated, for O₂, flammable gases, CO and H₂S (SOLAS XI-1/7)
- Ship-specific enclosed spaces register available and up to date (MSC.581(110))
- Enclosed space emergency response plan drafted and exercised in the drills
FAQ
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Last substantive revision of this page: 29 August 2026 · page fingerprint b845a8fb0749