Mixed Gas Diving Supervisor Cheat Sheet 2026: One-Page Review of Must-Know Facts

What This Cheat Sheet Covers (and What It Does Not)

This one-page-style review is for candidates preparing for the ADCI HeO2/mixed-gas diving supervisor examination. That means the Association of Diving Contractors International's credential, built on the ADCI International Consensus Standards, edition 6.5 (the PDF revision linked from the issuer homepage is dated July 27, 2025). It is not the ADC-UK scheme, and it is not an IMCA examination. If you have been studying material from those programs, set it aside for this exam; terminology, card structures and procedural expectations differ.

One honesty note before the facts. The five study groupings used throughout this site (and below) are editorial selections drawn from the published sections of the standards. They are not an official weighted exam blueprint, and nobody outside the issuer can promise exhaustive coverage of what appears on the test. Treat this sheet as a map of the source material you are accountable for, then verify against the standards themselves.

For a deeper walk through each grouping, see our Mixed Gas Diving Supervisor Exam Domains guide, and for the full preparation plan, the Mixed Gas Diving Supervisor Study Guide.

The Qualification Gates at a Glance

Passing the exam is only one gate. The standards stack several requirements before a mixed-gas supervisor card is valid for use on a job. Memorize the list; scenario questions often hinge on whether a person is actually qualified to supervise a given operation.

Section 3.6: The Supervisor Duty List You Must Know Cold

Section 3.6 of the standards covers mixed-gas supervisor duties, qualifications and card requirements. This is the single densest source section for the first grouping, HeO2/Mixed-Gas Diving Supervisor responsibilities, qualifications and certification. The responsibilities read like a checklist, and exam questions tend to test whether you can tell which duty applies to a described situation. Group them mentally into five clusters:

A useful exam habit: when a scenario describes something going wrong, ask which cluster the failure belongs to. A diver surfacing symptomatic with no chamber arrangements points to Cluster 5; a dive started without agreed termination criteria points to Clusters 2 and 4.

Surface-Supplied Mixed-Gas Operations (Section 4.4)

The second grouping, Surface-Supplied Mixed-Gas Diving (HeO2), draws from section 4.4, which sets out requirements for surface-supplied mixed-gas operational personnel and equipment. Expect questions that ask who must be on the team, what equipment must be on site, and what a supervisor must verify before the first dive of the day.

• Personnel: know the roles the standards require for a surface-supplied mixed-gas operation and who may fill them.
• Equipment on site: know what the standards require to be available for the mode, including emergency gas and the means to deal with a diver in distress.
• Gas supply planning: breathing-gas quantities are part of dive planning under section 3.6, so expect planning logic to connect the two sections.

Operations, Checklists and Dive Planning

The third grouping, Underwater Operations: Procedures, Checklists and Guidelines, pulls from the operations content in sections 5, 6 and 7 and ties back to the planning duties in 3.6. This is where procedural thinking is tested: sequence, documentation and go/no-go logic.

Pre-dive essentials to recall

• Job safety analysis completed and communicated at the team briefing
• Dive plan covering depth, time and gas profile, with gas supplies confirmed adequate
• Equipment inspected and confirmed suitable and compliant for the operation
• Current manuals plus decompression and treatment information on hand
• Team members' duties assigned and fitness confirmed
• Communication established with the vessel or site, and with emergency and medical support

During and after the dive

• Diver tended continuously, with no gaps in attention
• Termination criteria known to the team and applied when met
• Post-dive observation period with attention to symptoms
• Chamber availability and post-treatment arrangements confirmed
• Logs verified and maintenance records and incident reports completed

The recurring pattern in this grouping is that supervisors must be able to show their work on paper. Many questions reward the answer that documents, verifies or briefs rather than the one that simply proceeds.

Life-Support Equipment Quick Reference

The fourth grouping, Life-Support Equipment: Requirements, Maintenance and Testing, draws on the equipment sections of the standards. The scope is broad, so organize it by system rather than trying to memorize an undifferentiated list.

Emergency Procedures and Reporting

The fifth grouping, Emergency Procedures, Assessments and Reporting of Accidents, covers the emergency preparation material in the standards. The scenarios named in the source material give you a ready-made list to rehearse:

• Loss of breathing media
• Loss of communications
• Trapped or injured diver
• Umbilical damage
• Fire
• Equipment failure
• Adverse conditions

For each, rehearse a fixed response sequence: what the supervisor does first, what the standby or emergency resources do, how the dive is terminated, how medical support is engaged, and what gets reported afterward. The reporting piece matters: section 3.6 explicitly assigns the supervisor responsibility for incident reports and for verifying logs and maintenance records.

Registration, Card and Fee Mechanics

Here is what is and is not established about the administrative side.

• Exam format: the issuer's current certification page lists an online exam as required.
• Fee: the same page lists $275 for the supervisor card category. This is the issuer's listed figure for that category; it should not be described as an independently verified exam-only fee, and you should confirm current pricing directly with the issuer before budgeting.
• Not established: question count, time limit, passing score, pass rate and an official exam-weight table. If a site or forum post quotes these as fact, treat that as a red flag.

Because those details are not published, the safest assumption is that the exam can draw on any of the source sections. Our articles on the passing score, pass rate and exam dates explain what can and cannot be said responsibly, and the certification cost breakdown covers budgeting beyond the card fee, such as medical, training and travel.

Sequencing Your Review Around the Five Groupings

If you have a few weeks, order your review by dependency rather than by section number. Duties come first because every other grouping feeds back into them.

Practice questions are most useful after you have read the standards, not instead of reading them. Our Mixed Gas Diving Supervisor practice test is a good place to check whether the duty clusters and equipment logic have stuck. For a realistic sense of the challenge, see How Hard Is the Mixed Gas Diving Supervisor Exam?

Where the Card Fits in a Career

The mixed-gas supervisor card is a field credential: the standards require employer vetting and written assignment, which tells you the card works alongside an employer relationship rather than as a standalone license. It tends to matter for commercial diving contractors operating surface-supplied mixed-gas work. For market context, see the Mixed Gas Diving Supervisor Jobs and salary guide articles, and the ROI analysis if you are weighing the investment. This sheet deliberately avoids quoting earnings figures, since none are established in the source facts.

Frequently Asked Questions

For the broader picture of the credential itself, start with Mixed Gas Diving Supervisor Certification, and when you are ready to test yourself, head to the main practice test site.