- The Passing Score: What Is Actually Published
- Why No Cutoff Appears in the Standards
- What the Exam Is Built From: ADCI Consensus Standards 6.5
- The Real Gate: Prerequisites Before You Sit the Exam
- Aiming Past the Line: What to Master in Each Domain
- Fee and Registration Mechanics
- A Domain-Sequenced Readiness Plan
- Mistakes That Cost Points on Supervisor-Level Questions
- Frequently Asked Questions
- No official passing score, question count, or time limit for the ADCI HeO2/mixed-gas supervisor exam is established in the sources reviewed.
- The exam draws on ADCI International Consensus Standards edition 6.5, especially section 3.6 on mixed-gas supervisor duties and card requirements.
- Prerequisites are strict: 350 field days, 150 working dives, and 30 working days as assistant mixed-gas supervisor.
- The issuer's certification page lists $275 for the supervisor card category and an online exam as required.
The Passing Score: What Is Actually Published
Candidates searching for the passing score on the Mixed Gas Diving Supervisor exam want one clean number: a percentage, a scaled score, a count of questions they can miss. The honest answer is that the Association of Diving Contractors International (ADCI) does not publish one in the materials reviewed for this article. The question count, the time limit, the passing score, and the pass rate are all unestablished. There is also no official exam-weight table.
That matters because many sites fill this gap with confident-sounding figures borrowed from other credentials. This article does not do that. Here, "Mixed Gas Diving Supervisor" refers specifically to the ADCI HeO2/mixed-gas supervisor examination tied to the ADCI Consensus Standards. It is not an ADC-UK exam, not an IMCA exam, and not any other credential that happens to share a similar name, so numbers from those programs do not transfer.
Why No Cutoff Appears in the Standards
The ADCI Consensus Standards are an industry safety and operations document, not an exam candidate handbook. They define who may supervise mixed-gas operations, what that supervisor is responsible for, and what equipment and emergency provisions must be in place. They state that a supervisor must pass the specific ADCI HeO2/mixed-gas supervisor examination, but they do not publish scoring rules for it.
For a candidate, this changes how you should think about "passing." Without a published cutoff, the practical strategy is not to calculate the minimum you can get away with. It is to build competence across everything a mixed-gas supervisor is responsible for on a live dive. The exam is an entry check on the knowledge you will be accountable for on deck, in a control van, or at a dive station.
This also explains why the credential feels different from many professional exams. The consequences of a supervisor misunderstanding gas supply planning, decompression arrangements, or emergency response are not abstract. The exam content follows the duties, and the duties are broad.
What the Exam Is Built From: ADCI Consensus Standards 6.5
The most reliable way to prepare is source-based. The issuer's homepage currently links Consensus Standards edition 6.5 (the PDF revision filename carries the date July 27, 2025). The sections most relevant to this credential are:
- Section 3.6: mixed-gas supervisor duties, qualifications, and card requirements.
- Section 4.4: surface-supplied mixed-gas operational personnel and equipment requirements.
- Sections 5, 6, and 7: operations, equipment, and emergency preparation.
One caution: the five study groupings used on this site, and listed below, are editorial selections from the official standards. They are not a published weighted blueprint, and they are not proof of exhaustive exam coverage. Use them to organize your reading, not as a guarantee of what will appear. Our complete guide to all five content areas explains how each grouping maps to the standards.
| Study Grouping | Primary Source Emphasis |
|---|---|
| HeO2/Mixed-Gas Diving Supervisor responsibilities, qualifications and certification | Section 3.6 |
| Surface-Supplied Mixed-Gas Diving (HeO2) | Section 4.4 |
| Underwater Operations: Procedures, Checklists and Guidelines | Sections 5 and 6 (operations) |
| Life-Support Equipment: Requirements, Maintenance and Testing | Equipment provisions across sections 4.4 and 6 |
| Emergency Procedures, Assessments and Reporting of Accidents | Section 7 and related reporting duties |
The Real Gate: Prerequisites Before You Sit the Exam
For this credential, the hardest barrier is often not the exam score but eligibility. The standards and issuer materials describe a layered set of requirements. Passing the exam is only one item on the list:
- Pass the specific ADCI HeO2/mixed-gas supervisor examination.
- At least 350 field days as an air or mixed-gas diver.
- 150 working dives.
- 30 working days as assistant mixed-gas supervisor.
- Qualification as an air-diving supervisor.
- Employer vetting and written assignment.
- A mode-specific supervisor card.
- Medical fitness before hyperbaric exposure.
- Valid CPR and first aid.
The 30 working days as assistant mixed-gas supervisor is especially important for preparation. By the time you are eligible, you will have watched supervisory decisions made in real time. Use that exposure deliberately: when you observe a dive plan, a briefing, or a termination decision, connect it to the corresponding responsibility in section 3.6.
Aiming Past the Line: What to Master in Each Domain
With no weighting table, the safest approach is to treat all five groupings as in scope. Here is what to master in each, drawn from the published responsibilities and equipment and emergency provisions.
Domain 1: HeO2/Mixed-Gas Diving Supervisor responsibilities, qualifications and certification
This is the backbone, and section 3.6 lists a long set of duties. Know them as a connected chain rather than isolated facts.
- Compliance with regulations and the employer's manual.
- Responsibility for life-support equipment and immediate supervisory control of the dive.
- Coordination with vessels and sites, and choosing a suitable surface location.
- Pre-dive and post-dive checks, plus emergency and medical communications.
- Job safety analysis and dive planning, including gas supplies.
- Team duties and fitness, equipment suitability, compliance, and inspection.
- Current manuals, decompression and treatment information, and team briefings.
- Depth, time, and gas profiles; continuous tending; and termination criteria.
- Post-dive observation for symptoms, chamber availability, and post-treatment arrangements.
- Incident reports, maintenance records, and log verification.
Domain 2: Surface-Supplied Mixed-Gas Diving (HeO2)
Focus on the personnel and equipment requirements specific to surface-supplied mixed-gas operations in section 4.4. Be able to explain what must be in place before a dive starts and who is responsible for each element.
- Operational personnel requirements for a mixed-gas dive team.
- Equipment requirements specific to the mixed-gas mode.
- How these requirements differ from air-diving expectations.
Domain 3: Underwater Operations: Procedures, Checklists and Guidelines
Expect the exam to test operational judgment. Know how checklists support supervision, how operation-specific procedures are applied, and how planning documents translate into decisions during the dive.
- Dive planning inputs and operation-specific procedures.
- Use of depth, time, and gas profiles during execution.
- Criteria that trigger termination of a dive.
Domain 4: Life-Support Equipment: Requirements, Maintenance and Testing
The equipment provisions are broad. Build a mental inventory and tie each item to an inspection or testing expectation.
- Dress and emergency gas; helmets and masks; hoses and umbilicals.
- Compressors and air purity; manifolds and regulators.
- Launch and recovery, and entry and egress.
- Gauges and timekeeping; compressed-gas equipment.
- Pressure vessels for human occupancy; relevant maintenance and testing.
Domain 5: Emergency Procedures, Assessments and Reporting of Accidents
Supervisors are the decision-makers when something goes wrong. Be ready to reason through scenarios rather than recite lists.
- Loss of breathing media or communications.
- A trapped or injured diver.
- Umbilical damage, fire, equipment failure, and adverse conditions.
- Reporting duties and record verification after an incident.
Key Takeaway
Apply the mixed-gas context to everything you read. Some provisions in the standards are saturation-specific, and those should not be treated as universal mixed-gas exam requirements. When a passage is clearly about saturation systems, note it, but do not assume it is core to the surface-supplied HeO2 supervisor exam.
Fee and Registration Mechanics
The issuer's current certification page lists an online exam as required and shows $275 for the supervisor card category. A few clarifications keep this accurate:
- The $275 figure is the listed amount for the supervisor card category. It should not be read as an independently verified exam-only fee.
- The exam is described as an online requirement on the current certification page.
- Fees and procedures can change, so confirm directly with ADCI before you budget or register.
For a broader view of what getting certified can cost once training, medicals, and other items are included, see our certification cost breakdown. For timing questions, see the exam dates and scheduling guide.
A Domain-Sequenced Readiness Plan
Because the exam draws on a standards document rather than a commercial syllabus, sequence your study to follow the logic of the standards. Start with who the supervisor is, then move to the dive mode, the operations, the equipment, and finally what happens when things fail. This ordering lets later material build on earlier material.
Domain 1: Supervisor duties and qualifications
- Read section 3.6 slowly and list every responsibility in your own words.
- Memorize the prerequisite chain: 350 field days, 150 working dives, 30 days as assistant supervisor.
Domains 2 and 3: Surface-supplied HeO2 and operations
- Work through section 4.4 requirements for personnel and equipment.
- Trace a dive from planning through termination criteria using sections 5 and 6.
Domain 4: Life-support equipment
- Build an equipment inventory from dress and emergency gas through pressure vessels for human occupancy.
- Pair each item with its maintenance and testing expectation.
Domain 5: Emergencies, then full review
- Walk through each emergency type in section 7 as a supervisor decision sequence.
- Take timed practice questions across all five areas and revisit weak spots.
For a fuller approach, our Mixed Gas Diving Supervisor study guide expands on this plan, and the one-page cheat sheet is useful for last-pass review. You can also test yourself with realistic questions on the Mixed Gas Diving Supervisor practice test site.
Mistakes That Cost Points on Supervisor-Level Questions
Treating the exam as a memorization exercise
The duties in section 3.6 are meant to be applied. A question may present a situation, such as a gas supply concern or a symptom after a dive, and ask what the supervisor must do or verify. Know the reason behind each duty, not just its wording.
Importing rules from other programs
Diving standards differ between organizations. Do not substitute ADC-UK or IMCA material for ADCI Consensus Standards 6.5. If a procedure you learned elsewhere differs from the ADCI text, the ADCI text is your reference for this credential.
Confusing saturation provisions with surface-supplied mixed-gas requirements
The standards cover more than one operating mode. Keep your attention on the surface-supplied mixed-gas context and set saturation-specific provisions aside unless a passage clearly applies.
Ignoring documentation and reporting
Incident reports, maintenance records, and log verification are part of the supervisor's responsibilities. Candidates who focus only on in-water operations often underprepare for these duties. For perspective on overall difficulty, read how hard the Mixed Gas Diving Supervisor exam is.
Frequently Asked Questions
No official passing score is established in the sources reviewed. The question count, time limit, and pass rate are also unpublished. Confirm current details with ADCI directly rather than relying on figures from third-party sites.
No. There is no published weighted exam blueprint. The five study groupings on this site are editorial selections from the ADCI Consensus Standards, so prepare for all of them rather than skipping any.
The issuer homepage currently links ADCI International Consensus Standards edition 6.5. Focus on section 3.6 for supervisor duties and card requirements, section 4.4 for surface-supplied mixed-gas requirements, and sections 5, 6, and 7 for operations, equipment, and emergency preparation.
The issuer's certification page lists $275 for the supervisor card category and shows an online exam as required. This should not be treated as an independently verified exam-only fee, so confirm current pricing with ADCI before registering.
The credential requires at least 350 field days as an air or mixed-gas diver, 150 working dives, and 30 working days as assistant mixed-gas supervisor, along with air-diving supervisor qualification, employer vetting, medical fitness, and valid CPR and first aid. See the requirements guide for the full list.
Since no published cutoff tells you how little you can get away with knowing, the strongest preparation is full command of the supervisor's duties, the equipment provisions, and the emergency responses in the ADCI standards. Build that foundation, check it against realistic questions on the practice test site, and the score will take care of itself.
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