I. INTRODUCTION
The TDI Trimix Instructor Course provides the training required to competently and safely teach breathing gases containing helium for dives that require staged decompression to a maximum depth of three hundred thirty (330) fsw / one hundred (100) msw. The objective of this course is to train Instructors to teach the benefits, hazards and proper procedures of utilizing custom oxygen/helium/nitrogen mixtures as breathing gases.

II. QUALIFICATIONS OF GRADUATES
Graduates may engage in teaching activities utilizing custom Trimix mixtures as long as:
1. The diving activities approximate those of training.
2. The areas of activities approximate those of training.
3. Environmental conditions approximate those of training.
4. May teach Entry level Trimix or Advanced Trimix.

III. WHO MAY TEACH
Who may teach this course:
1. Any active TDI Trimix Instructor Trainer may teach this course.

IV. STUDENT – INSTRUCTOR RATIO
Academic:
1. Unlimited, so long as adequate facility, supplies and time are provided to insure comprehensive and complete training.
Confined Water (Swimming pool-like conditions):
1. N/A
Open Water (Ocean, lake, quarry, spring, river or estuary):
1. A maximum of four (4) students per Instructor Trainer. However, it is the Instructor Trainer’s discretion to reduce this number as conditions dictate.

V. STUDENT PRE-REQUISITES
The student must:
1. Be a minimum age of twenty one (21).
2. Show proof of minimum certification as a TDI Advanced Trimix Diver.
3. Show proof of minimum certification as a TDI Extended Range Instructor (or equivalent).
4. Show proof of minimum two hundred fifty (250) logged dives.
1. Show proof of minimum of fifteen (30) logged Trimix dives.
2. Show proof of 20 dives deeper than one hundred and eighty (180) feet/ Fifty five (55) meters.
And meet one of the following experience requirements
3. Certify at least 10 Extended Range Divers to depths of at least 150 feet.
4. Assist with at least 2 complete Advanced TRIMIX classes taught by a TDI TRIMIX Instructor and provide a letter of recommendation from the assisted instructor(s).

VI. COURSE STUCTURE AND DURATION
Open Water Execution:
1. Four (4) Dives with a minimum accumulated bottom time of one hundred (100) minutes.
2. Two (2) of the dives must be deeper than two hundred thirty (230) / seventy (70) meters
Course Structure:
1. TDI allows instructors to structure courses according to the number of students participating and their skill level.
Duration:
1. The recommend number of classroom and briefing hours is eight (8).

VII. ADMINISTRATIVE REQUIREMENTS
The following is the administrative tasks:
1. Collect the course fees from all the students.
2. Ensure that the students have the required equipment.
3. Communicate the training schedule to the students.
4. Have the students complete the Liability Release and Medical history forms.
5. The Instructor should review the Liability Release and Medical Forms before starting on the course.
5. Upon successful completion of the course the Instructor must:
6. Complete the Student Registration Form and send the Registration Form to TDI HQ.
7. Award card and certificate.

VIII. REQUIRED EQIPMENT
The following are required for this course:
1. TDI Standards and Procedures Instructor Manual.

The following equipment is required for each student:
1. Bottom mix cylinder(s)
     A. Cylinder volume appropriate for the planned dive and candidate gas consumption.
     B. Dual outlet valve or manifold required.
     C. Labeled in accordance with TDI standards.
2. Travel mix cylinder(s)
     A. Cylinder volume appropriate for planned dive and candidate consumption.
     B. Labeled in accordance with TDI standards.
3. Decompression mix cylinder(s)
     A. Cylinder volume appropriate for planned dive and candidate gas consumption.
     B. Labeled in accordance with TDI standards.
4. Suit inflation cylinder (required for dry-suit divers only).
5. Regulators
     A. Primary and primary redundant required on all bottom mix cylinder(s).
     B. Submersible pressure gauges are required on all primary/bottom mix cylinders.
     C. One primary regulator must have a sufficient length hose for air sharing.
     D. It is strongly recommended that all 4 required regulators be DIN or all 4 regulators be yoke.
6. Buoyancy compensators as appropriate for equipment configuration.
7. Redundant depth and timing devices. Air decompression computers allowed for use as depth and timing devices.
8. Redundant light system (if required by site).
9. Ascent reel with lift bag
10. Adequate for planned maximum depth.
11. Minimum fifty (50) lb lift bag / surface marker buoy ( a dump valve highly recommended).
12. Exposure suit adequate for the open water environment.
13. Line cutting device.
14. Underwater slate.

IX. REQUIRED SUBJECT AREAS
Instructor Trainers must use the TDI Trimix Instructor Guide and current TDI Standards and Procedures Instructor Manual, but may also use any additional text or materials they feel help present these topics. The following topics must be covered in this course:
1. Physics
     A. Pressure review.
2. Physiology
     A. Hypoxia.
     B. Oxygen Toxicity
          I. Whole Body.
          II. Central Nervous System (CNS).
     C. Nitrogen narcosis.
     D. Nitrogen and helium absorption and elimination.
     E. Carbon monoxide toxicity.
     F. Carbon dioxide toxicity.
     G. Helium
          I. HPNS.
          II. Effects on respiration.
          III. Effects as an insulator.
     H. Counter diffusion.
     I. Hyperthermia.
     J. Hypothermia.
3. Decompression Options
     A. Air.
     B. Nitrox.
     C. Helium.
4. Equipment Options
     A. Twin cylinder options.
     B. Stage cylinder option.
     C. Suit inflation options.
     D. Regulator options.
     E. Harness / BC options.
     F. Computer / depth gauge / bottom timer options.
     G. Ascent and navigation reels.
     H. Lift bags.
     I. Lights.
     J. Redundant mask and knife.
     K. Jon-line.
5. Dive Tables
     A. Computer generated tables.
     B. DCIEM Heliox Tables and / or other published tables.
6. Dive Planning
     A. Operation Planning
          I. Support.
          II. Teams.
     B. Team Planning
          I. Gas requirements.
          II. Oxygen limitations.
          III. Inert gas limitations.
     C. Emergency Planning
          I. Omitted deco.
          II. Oxygen toxicity.
          III. Decompression sickness.
7. General Procedures
     A. Bottom, Travel and Decompression Gas.
          I. Normal operations.
          II. Failure, loss or inadequate emergency procedures.
          III. Analyzing and logging.

X. REQUIRED SKILL PERFORMANCE AND GRADUATION REQUIREMENTS
The following skills must be completed by the Instructor candidate. It is recommended that all dives be conducted between one hundred eighty (180) fsw / fifty five (55) msw and three hundred thirty (330) fsw / one hundred (100) msw.
1. Properly demonstrate analysis of all gas mixtures to be used.
2. Demonstrate adequate pre-dive planning
     A. Limits based on personal and team gas consumption.
     B. Limits based on oxygen exposures at planned depths for actual mixes.
     C. Limits based on inert gas absorption at planned depth with actual mixes.
3. Properly execute the planned dive within all pre-determined limits.
4. Demonstrate the proper navigational techniques for the specific dive.
5. On two (2) of the dives, demonstrate an ascent with ascent reel and bag. Perform staged decompression.
6. Demonstrate the proper procedures for switching and isolating a malfunctioning primary regulator.

In order to complete this course, students must:
1. Satisfactorily complete the TDI Trimix Course written examination and be able to adequately explain each answer to a prospective student.
2. Demonstrate mature, sound judgment concerning training, dive planning and execution.
3. Complete all open water requirements safely and efficiently.
4. Demonstrate proficiency in teaching the TDI Trimix Diver Program.
5. One (1) graded presentation on a Trimix topic.