A single Port State Control detention can cost between a quarter of a million and more than a million dollars a day once lost charter hire, demurrage, cargo-delay claims, port costs and remedial work are added up — and unlike a random accident, it is almost entirely predictable. The same handful of deficiency categories has dominated global detention statistics for over a decade, and the codes behind them barely change from quarter to quarter. In the first quarter of 2026, detentions were once again led by two sub-categories: 15150, ISM implementation, and 15109, maintenance of ship and equipment, exactly as in the quarters before. What makes detention codes worth understanding is that they are not just labels applied after the fact — they reveal how inspectors think, which failures they treat as serious enough to hold a ship, and, crucially, how a collection of small, individually harmless findings can combine into a single detainable conclusion that the safety management system itself is not working. For the fleet managers, Designated Persons Ashore and masters who carry detention risk, knowing the codes is knowing where the danger concentrates. This guide explains the deficiency codes behind most detentions, why ISM and maintenance lead the list, how the accumulation of minor items becomes a detention in its own right, and how to prevent each of the leading categories. To keep the inspections, maintenance records and certificate evidence that prevent these codes organised and audit-ready across your fleet, start a free trial or book a demo.
COMPLIANCE GUIDE · PORT STATE CONTROL
PSC Detention Codes Explained: The Top Deficiencies and How to Prevent Them
The deficiency codes behind most Port State Control detentions — why ISM implementation (15150) and maintenance (15109) lead quarter after quarter, how minor findings accumulate into a detainable ISM conclusion, and a prevention playbook for each leading category.
$250K–$1M+
Potential daily cost of a detention
15150 & 15109
The codes leading detentions quarter after quarter
36 months
How long a detention stays on the risk profile
How a Detention Actually Happens
Detention is not triggered by any single missing document. A ship is detained when deficiencies are clearly hazardous to safety, health or the environment, or constitute serious or repeated breaches of a convention — and critically, that judgement can rest on an accumulation of findings, not one dramatic fault. Understanding this mechanism is the key to understanding the codes.
The ISM multiplier effect
Multiple deficiencies that are each individually non-detainable can collectively demonstrate a systemic failure of the safety management system. The Paris MOU defines this explicitly: if the inspector concludes the deficiencies provide objective evidence of a failure of the ISM system, an ISM-related detainable deficiency — code 15150 — is recorded. This is why a single unmaintained fire door, with no record of inspection in the planned maintenance system and a crew who cannot explain the procedure, stops being a minor item and becomes an ISM failure. Analysis of more than 125,000 inspection records shows that five or more deficiencies in a single inspection significantly increases the probability of detention, because that is the threshold at which a pattern, rather than an isolated fault, becomes visible.
This is the single most important idea behind the detention codes: 15150 is so often the leading code not because inspectors are hunting for ISM paperwork, but because the ISM conclusion is where an accumulation of unrelated small failures lands. A fleet that treats every minor deficiency as trivial is building, item by item, toward the systemic conclusion that gets the ship held. The categories below are where those items most often come from. To catch and close the small deficiencies before they accumulate into an ISM conclusion, start a free trial or book a demo.
The Leading Detention Codes
The detainable deficiency codes cluster into a predictable set of categories that dominate detention statistics across the Paris MOU, Tokyo MOU and US Coast Guard. These are the ones that account for the majority of detentions, and the failures inspectors most often cite within each.
15150
ISM implementation
The most frequently cited detainable sub-category across all three regimes. Recorded when the safety management system is judged not to be working — often as the conclusion drawn from an accumulation of other deficiencies, or from a crew unable to demonstrate the system lives in daily routine rather than only on paper.
15109
Maintenance of ship and equipment
The primary category for the Tokyo MOU and US Coast Guard, which use this code specifically. Cited when equipment condition shows maintenance has not been carried out or recorded, tying directly to the planned maintenance system and the evidence that upkeep is real rather than claimed.
Fire Safety
Consistently the top or second category
Around a fifth of inspection findings and frequently the single leading detainable category. Inoperative fire-detection panels, damaged detectors, fire doors that will not close, expired extinguishers, and fixed CO2 or foam systems overdue for service are the most cited findings.
LSA
Life-saving appliances
Appearing in a large share of inspections. Lifeboat release mechanisms, davits, fall ropes, EPIRBs and immersion suits are the recurring items — equipment that must not only exist but demonstrably function on test, which is where many are found wanting.
Certs
Certificates and documentation
Expired or missing certificates, lapsed endorsements and incomplete record books. Straightforward to prevent and yet a persistent detention driver, because a certificate that lapses unnoticed is an avoidable finding that points to weak oversight.
Emerg
Emergency systems and navigation
Emergency power failing to take load on test, emergency fire pumps, and on the navigation side ECDIS chart updates, VDR playback and BNWAS function. These surface under functional verification, where the inspector watches the system perform rather than reading its certificate.
i
Inspectors verify function, not just paperwork
In a more detailed inspection the officer moves from documentary to functional verification — an emergency generator start, an emergency fire pump test, remote closing of ventilation flaps, an abandon-ship drill with a boat lowered, a general alarm test. This kind of inspection is mandatory for high-risk ships and for tankers, bulk carriers and passenger ships over twelve years old, and it typically takes a full day. The inspector wants to watch the crew perform, not read the procedure, which is why a certificate proving a system was serviced does not protect a vessel if that system then fails on test. Prevention has to make the equipment actually work and the crew actually able to operate it, because that is what is verified.
The codes are predictable — so prevention can be systematic
The same categories drive detentions year after year, which means they can be pre-empted. Marine Inspection ties inspections to the planned maintenance system, tracks certificate expiry, and evidences drills and functional tests — so the findings behind 15150 and 15109 are caught and closed before an inspector arrives.
Preventing Each Leading Category
Because the categories are predictable, so is the prevention. Each leading code maps to a specific discipline that keeps the finding from arising, and together they add up to the living safety management system inspectors are really assessing.
Fire safety
Test and maintain fire-detection panels and detectors on schedule, keep fire doors free to self-close, service fixed systems before they fall due, and check extinguisher dates — and record every check, because an untested fire door with no maintenance record is how a minor item becomes an ISM finding.
Maintenance (15109)
Run a genuine planned maintenance system where jobs are done on time and the record proves it. Equipment condition must match the maintenance history, so the discipline is not just doing the work but capturing evidence an inspector can see that upkeep is real and current.
Life-saving appliances
Function-test lifeboat release gear, davits and fall ropes, keep EPIRBs and immersion suits in date and serviceable, and drill their use, so the equipment demonstrably works on test rather than merely being present and certificated.
Certificates and documentation
Track every statutory and class certificate, endorsement and record book with tiered expiry alerts, so nothing lapses unnoticed. This is the most avoidable category, and preventing it is largely a matter of never being surprised by an expiry date.
Emergency and navigation systems
Regularly function-test emergency power under load, emergency fire pumps and ventilation closing, and keep ECDIS charts updated, VDR functional and BNWAS operational, because these are checked by operation, not by certificate.
ISM (15150) — the umbrella
Prevent the systemic conclusion by closing every minor deficiency promptly with a recorded corrective action, so no accumulation of small items can be read as objective evidence the system has failed. A living, evidenced safety management system is the ultimate defence against the leading code.
Why the Codes Matter Beyond the Detention
The immediate cost of a detention is only part of the picture. The codes recorded against a vessel follow it, and the fleet, well after the ship is released, which is why prevention is a strategic concern rather than an operational inconvenience.
A detention enters the ship's thirty-six-month history and the ISM company's performance record, affecting the risk profile of every vessel under that management. Under the New Inspection Regime, a ship's risk profile determines how often it is inspected — a high-risk vessel sees an inspector far more frequently than a low-risk one — so a detention makes future inspections both more likely and more searching, in a cycle that is hard to break. Beyond frequency, there is the ultimate sanction of banning: in the Paris MOU region, a ship on a black-listed flag can be refused access after three detentions in thirty-six months, and one on a grey-listed flag after three in twenty-four months. And a single detention typically results from several converging findings rather than one fault, which means the prevention discipline that stops one code from being recorded tends to stop the others too. The vessel that closes its minor deficiencies, maintains its equipment with evidence, keeps its certificates current and can demonstrate its systems working on test is not just avoiding one detention — it is protecting its risk profile, its access to ports, and the standing of every sister ship in the fleet. That is the real return on understanding the codes: not passing a single inspection, but staying off the trajectory that makes detention likely. To keep the maintenance evidence, certificate tracking and corrective-action records that protect your fleet's risk profile in one connected system, start a free trial or book a demo.
Frequently Asked Questions
What are the most common PSC detention codes?
The two most frequently cited detainable sub-categories are 15150, ISM implementation, and 15109, maintenance of ship and equipment — the latter used specifically by the Tokyo MOU and the US Coast Guard. They lead detention statistics quarter after quarter across the major regimes. Beyond these two codes, the dominant categories are fire safety (often the single leading category, covering detectors, fire doors, extinguishers and fixed systems), life-saving appliances (lifeboats, davits, EPIRBs, immersion suits), certificates and documentation (expired or missing certificates and incomplete record books), and emergency and navigation systems. These same categories have dominated detention data for over a decade, making them predictable and therefore preventable.
What is deficiency code 15150?
Code 15150 is the ISM implementation deficiency, recorded when a Port State Control officer concludes the vessel's safety management system is not functioning effectively. It is consistently the most cited detainable sub-category across the Paris MOU, Tokyo MOU and US Coast Guard. Importantly, it is frequently the conclusion drawn from an accumulation of other deficiencies rather than a single ISM fault: the Paris MOU explicitly records an ISM-related detainable deficiency when the collected findings provide objective evidence of a failure of the ISM system. So 15150 often captures the systemic pattern behind a set of smaller individual failures, which is why it leads the statistics.
Can minor deficiencies alone cause a detention?
Yes, through what is known as the ISM multiplier effect. Multiple deficiencies that are each individually non-detainable can collectively demonstrate a systemic failure of the safety management system, and the Paris MOU explicitly records an ISM detainable deficiency when the findings provide objective evidence that the ISM system has failed. Analysis of more than 125,000 inspection records shows that five or more deficiencies in a single inspection significantly increases detention probability, because that is where an isolated fault gives way to a visible pattern. This is why treating every minor item as trivial is dangerous: a single unmaintained fire door with no record and a crew who cannot explain the procedure can become an ISM failure.
What does deficiency code 15109 cover?
Code 15109 covers maintenance of ship and equipment, and it is the primary detainable category used by the Tokyo MOU and the US Coast Guard. It is recorded when equipment condition shows that maintenance has not been properly carried out or recorded, tying directly to the vessel's planned maintenance system. The key to preventing it is that equipment condition must match the maintenance history — it is not enough to have a maintenance schedule if the physical state of the equipment contradicts it. Preventing 15109 means running a genuine planned maintenance system where jobs are completed on time and the record provides evidence, visible to an inspector, that upkeep is real and current rather than merely claimed on paper.
How much does a PSC detention cost?
A single detention can cost between roughly a quarter of a million and over a million dollars per day once all consequences are counted: lost charter hire, demurrage, cargo-delay claims, additional port costs, and remedial work including express freight for parts and service engineers. The commercial cost — charter-party breach, penalties and lost berth windows — is almost always the heaviest single item. Beyond the immediate financial impact, a detention enters the ship's thirty-six-month history and the ISM company's performance record, worsening the risk profile of every vessel under that management and increasing future inspection frequency. In the most serious cases, repeated detentions can lead to banning from a region entirely.
How long does a detention affect my vessel?
A detention remains on the ship's history for thirty-six months and also affects the ISM company's performance record, which influences the risk profile of every vessel under that management. Under the New Inspection Regime, the risk profile determines inspection frequency, so a detention makes the vessel more likely to be inspected and more likely to face a searching, functional inspection, creating a cycle that takes time and clean inspections to escape. In the Paris MOU region there is a further consequence: a ship on a black-listed flag can be banned after three detentions in thirty-six months, and one on a grey-listed flag after three in twenty-four months. This durability is why preventing the leading codes is a strategic priority, not just an inspection-day concern.
Prevent the Codes Before the Inspector Arrives
The codes behind detention are predictable, which means they are preventable. Marine Inspection ties inspections to the planned maintenance system, tracks every certificate with expiry alerts, evidences drills and functional tests, and converts every minor deficiency into a tracked corrective action — so the small findings never accumulate into a 15150 ISM conclusion, and your fleet's risk profile stays protected. Turn detention prevention from a hope into a system.
