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15.1 Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC
FAA Aircraft Dispatcher Certificate ADX
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1 Chapter 1: Regulations, Certification & Operational Control
1.1 Part 65 Subpart C: Certification, Eligibility & Currency 1.2 Operational Control & Dispatcher-PIC Joint Responsibility 1.3 Domestic, Flag & Supplemental Operations Framework 1.4 Dispatch Release Elements, Signatures & Recordkeeping 1.5 Regulations, Manuals, Crew Qualifications, and Source Control
2 Chapter 2: Atmospheric Physics, Pressure Systems & Fronts
2.1 Atmospheric Structure, Standard Atmosphere & Altimetry 2.2 Air Masses, Frontal Systems & Frontogenesis 2.3 Atmospheric Stability, Lapse Rates & Cloud Formation 2.4 Earth Motion, Regional Weather, Local Winds, and Water Phase Changes
3 Chapter 3: Aviation Weather Hazards & Severe Weather Avoidance
3.1 Structural and Induction Icing: Types, Accretion & Operations 3.2 Thunderstorms, Squall Lines, Microbursts & Low-Level Windshear 3.3 Clear Air Turbulence (CAT), Mountain Waves & Jet Streams 3.4 Low Ceilings, Fog Types & Visibility Restrictions 3.5 Hurricanes, Typhoons, Tornadoes, and Tropical Dispatch Hazards
4 Chapter 4: Weather Observations, Forecasts & Advisories Decoding
4.1 METAR and SPECI Surface Observations: Decoding & Operations 4.2 Terminal Aerodrome Forecasts (TAF): Groups & Timing 4.3 Pilot Weather Reports (PIREP): Coding, Severity & Urgent Alerts 4.4 In-Flight Advisories: AIRMETs, SIGMETs & Convective SIGMETs 4.5 Weather Collection, NWS Facilities, GFA, and EWINS
5 Chapter 5: Aviation Weather Charts & Upper-Air Analysis
5.1 Surface Analysis & Radar Summary Charts 5.2 Constant Pressure Analysis & Winds Aloft (FB) 5.3 Significant Weather Prognostic Charts (SIGWX) 5.4 Satellite Imagery, Moisture-Stability Analysis, and Forecast Integration
6 Chapter 6: Air Navigation, Airspace Architecture & Route Structure
6.1 National Airspace System: Classes, Rules & Special Use 6.2 Ground-Based Navigation Aids & Standard Service Volumes 6.3 Area Navigation (RNAV), GNSS/GPS, PBN & RNP Fundamentals 6.4 En Route Airways, SIDs, STARs & Chart Interpretation 6.5 Earth Coordinates, UTC, Chart Projections, and Flight Instruments 6.6 North Atlantic, Pacific, RVSM, and Global Navigation Differences
7 Chapter 7: Instrument Approaches, Minimums & Airport Operations
7.1 Precision Approach Systems: ILS Categories & Tolerances 7.2 Non-Precision Approaches, RNAV & Decision Minimums (MDA/DA) 7.3 Takeoff Minimums, Lower-Than-Standard & Takeoff Alternates 7.4 Holding Procedures: Patterns, Speed Limits & Timing
8 Chapter 8: Subsonic Aerodynamics & Jet Aircraft Performance
8.1 Subsonic Jet Aerodynamics: Lift, Drag & Flight Regimes 8.2 High-Altitude Flight: Mach Number, Buffet & Coffin Corner 8.3 Transport Turbine Engines: Thrust, Specific Fuel & Bleed Air
9 Chapter 9: Transport Category Takeoff & Landing Runway Analysis
9.1 Takeoff Performance Speeds & Balanced Field Concept 9.2 Takeoff Climb Segments & Obstacle Clearance Gradients 9.3 Landing Performance: Field Lengths, 60% Rule & Contamination
10 Chapter 10: En Route Performance, Driftdown Profiles & ETOPS Operations
10.1 One/Two-Engine-Inoperative En Route Net Profiles & Driftdown 10.2 Extended-Range Operations (ETOPS): Philosophy & Regulations 10.3 ETOPS En Route Alternates: Adequate vs. Suitable & Critical Fuel
11 Chapter 11: Aircraft Weight & Balance, Center of Gravity, and Loading
11.1 Transport Aircraft Structural Weight Limits: Definitions & Rules 11.2 Center of Gravity Computations: Datum, Arm, Moment & Index 11.3 Mean Aerodynamic Chord (%MAC) Computations & Stability 11.4 Payload-Range Analysis, Zero Fuel Weight Tradeoffs & Loading
12 Chapter 12: Destination Alternate Airport Selection & Weather Rules
12.1 Destination Alternate Selection: 91.169 & Part 121 1-2-3 Rule 12.2 Flag & Supplemental Operations Destination Alternate Rules 12.3 Derived Alternate Minimums: 1-Nav and 2-Nav Facility Rules
13 Chapter 13: Part 121 Fuel Planning, Reserves & En Route Re-Release
13.1 Part 121 Domestic Fuel Requirements: Reserves & Calculations 13.2 Part 121 Flag Fuel Requirements: 10% Reserve & Island Rules 13.3 Supplemental Fuel Requirements & Holding Fuel Management 13.4 Redispatch and En Route Re-release Procedures
14 Chapter 14: Transport Systems, Pressurization & MEL/CDL Procedures
14.1 Transport Jet Auxiliary Power, Electrical, Hydraulic & Pneumatic Systems 14.2 Cabin Pressurization, Rapid Decompression & Oxygen Requirements 14.3 Master Minimum Equipment List (MMEL), MEL & CDL Procedures 14.4 Flight Controls, Autoflight, Fuel, Oil, Brakes, and Fire Protection
15 Chapter 15: Hazardous Materials, Duty Regulations & Emergency Procedures
15.1 Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC 15.2 Dispatcher Duty Limitations, Rest Requirements & Fatigue 15.3 Emergency Authority, Declaration & Diversion Decision-Making 15.4 NTSB Part 830 Accident Reporting & Wreckage Preservation 15.5 Security, Overdue Aircraft, and FAA Emergency Services
16 Chapter 16: Communications, ATC, and Flight Plan Procedures
16.1 Voice, Data Link, Position Reports, and Lost Communications 16.2 ATC Facilities, Separation, ICAO Flight Plans, and Traffic Management
17 Chapter 17: Human Factors and Practical Dispatch Applications
17.1 Dispatch Resource Management, Human Error, and Risk Decisions 17.2 Manual Flight Planning, PIC Briefing, Flight Watch, and Postflight Closeout
15.1 Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC
Key Takeaways Explain This Topic AI
Dangerous goods transport in U.S. civil aviation is governed by 49 CFR Part 175, harmonized with ICAO Technical Instructions (Doc 9284) and the IATA Dangerous Goods Regulations (DGR).
Hazardous materials are classified into 9 distinct DOT hazard classes, ranging from Class 1 Explosives to Class 9 Miscellaneous Dangerous Goods.
§ 175.33 requires written shipment information to the PIC and operational-control personnel before movement under the aircraft’s own power, with specified contents and exceptions.
Passenger aircraft face strict quantity and hazard restrictions, whereas Cargo-Only Aircraft (CAO) can carry larger quantities and hazardous classes forbidden on passenger flights.
Both 'Will-Carry' and 'Will-Not-Carry' certificate holders must maintain FAA-approved Hazmat Recognition Training Programs to intercept undeclared hazardous materials and safely manage company material (COMAT).
Last updated: October 2026
Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC
Quick Summary: The carriage of hazardous materials (HAZMAT) or dangerous goods by air is strictly controlled to prevent catastrophic inflight fires, toxic contamination, explosions, or corrosive structural damage. In the United States, Title 49 of the Code of Federal Regulations (49 CFR) Part 175 governs commercial air carriers, harmonizing federal law with the International Civil Aviation Organization (ICAO) Technical Instructions. Aircraft dispatchers exercise joint operational control over flights carrying dangerous goods, ensuring package compatibility, cargo compartment limits, and the accurate delivery of the mandatory Notice to Pilot in Command (NOTOC).
1. Regulatory Framework: 49 CFR Part 175, ICAO & IATA
The air transport of hazardous materials exists within a layered domestic and international legal regime:
49 CFR Parts 171–180 (Hazardous Materials Regulations - HMR): Promulgated by the Pipeline and Hazardous Materials Safety Administration (PHMSA) under the U.S. Department of Transportation (DOT), and actively enforced in aviation by the Federal Aviation Administration (FAA) Office of Hazardous Materials Safety. 49 CFR Part 175 specifically details the operating rules for carriage aboard aircraft.
ICAO Annex 18 & Technical Instructions (Doc 9284): The Safe Transport of Dangerous Goods by Air provides the global statutory baseline established by the United Nations specialized agency.
IATA Dangerous Goods Regulations (DGR): A field manual published by the International Air Transport Association that incorporates all ICAO Technical Instructions alongside carrier- and state-specific variations. Commercial air carriers commonly utilize the IATA DGR for day-to-day station acceptance.
Under federal law, any substance capable of posing an unreasonable risk to health, safety, and property when transported in commerce is designated as a hazardous material. The atmospheric environment of flight—characterized by reduced ambient pressure at altitude, continuous vibration, and extreme temperature fluctuations in unheated cargo holds—exacerbates chemical volatility, vapor pressure venting, and package leakage risks.
2. The 9 DOT Hazard Classes
Hazardous materials are categorized into nine primary classes based on their chemical and physical hazard characteristics. Many classes are further segmented into numerical divisions reflecting specific danger mechanisms:
Class Hazard Designation Key Divisions / Examples Flight Restrictions
Class 1 Explosives Div 1.1–1.3 (mass explosion, projection; forbidden on passenger aircraft); Div 1.4 (minor explosion hazard, e.g., small arms cartridges UN 0012, emergency flares) Highly restricted; Div 1.1–1.3 strictly prohibited on passenger aircraft. Div 1.4S allowed in limited quantities.
Class 2 Gases Div 2.1 (Flammable Gas, e.g., propane, butane); Div 2.2 (Non-Flammable/Non-Toxic, e.g., compressed nitrogen, cryogenic neon, medical oxygen); Div 2.3 (Toxic Gas, e.g., chlorine, phosgene) Div 2.3 toxic gases are completely forbidden on all passenger aircraft and most cargo operations.
Class 3 Flammable Liquids Liquids with a flashpoint ≤ 60 ∘ C \le 60^\circ\text{C} ≤ 6 0 ∘ C ( 140 ∘ F 140^\circ\text{F} 14 0 ∘ F ), e.g., aviation fuel (UN 1863), gasoline, ethanol solutions, oil-based paints Strictly limited by net volume per package; packing group dictates container durability.
Class 4 Flammable Solids Div 4.1 (Flammable solids, e.g., matches, sulfur); Div 4.2 (Spontaneously combustible, e.g., white phosphorus, activated carbon); Div 4.3 (Dangerous when wet, e.g., sodium, potassium, calcium carbide) Div 4.2 and 4.3 carry severe water-reaction risks, requiring strict separation from moisture and food.
Class 5 Oxidizers & Organic Peroxides Div 5.1 (Oxidizers yielding oxygen, e.g., ammonium nitrate, potassium permanganate); Div 5.2 (Organic Peroxides, thermal instability, e.g., benzoyl peroxide) Highly restricted. Chemical oxygen generators (UN 3356) are forbidden unless installed or approved under strict exemptions.
Class 6 Toxic & Infectious Substances Div 6.1 (Toxic substances, e.g., cyanide, pesticides); Div 6.2 (Infectious substances, Category A pathogens like Ebola/Anthrax UN 2814, Category B biological substances UN 3373) Category A infectious substances require specialized packaging and immediate carrier notification.
Class 7 Radioactive Materials Radioactive isotopes, radiopharmaceuticals (technetium-99m), industrial density gauges Quantified by Transport Index (TI); strict cumulative TI limits per compartment and separation distances.
Class 8 Corrosives Liquids or solids causing full-thickness destruction of skin tissue or severe corrosion to aluminum/steel (e.g., sulfuric acid, wet cell batteries UN 2794, sodium hydroxide) Must be segregated from flammables and cyanides; must avoid contact with aircraft aluminum structure.
Class 9 Miscellaneous Dangerous Goods Substances presenting a hazard not covered by other classes: Dry Ice (UN 1845), Lithium Ion Batteries (UN 3480/3481), Lithium Metal Batteries (UN 3090/3091), Magnetized Materials Dry ice poses carbon dioxide asphyxiation risk; lithium batteries present thermal runaway fire risks.
Packing Groups
Except for Classes 1, 2, and 7, dangerous goods are assigned a Packing Group (PG) indicating the degree of danger:
Packing Group I (PG I): High danger (demands the most robust, drop-tested UN performance packaging).
Packing Group II (PG II): Medium danger.
Packing Group III (PG III): Low danger.
3. Forbidden Materials vs. Cargo Aircraft Only (CAO)
Not all dangerous goods are eligible for air transportation:
Forbidden Under All Circumstances: Materials that are prone to detonate, violently decompose, or spontaneously ignite under temperature conditions up to 55 ∘ C 55^\circ\text{C} 5 5 ∘ C ( 131 ∘ F 131^\circ\text{F} 13 1 ∘ F ) or pressure differentials common to flight. Examples include unapproved unstable explosives, chemical oxygen generators without thermal safety caps, and liquid hydrogen.
Forbidden on Passenger Aircraft, Permitted on Cargo-Only Aircraft (CAO): Items carrying hazards that exceed cabin survivability thresholds. Packages bearing the orange Cargo Aircraft Only handling label cannot be loaded onto passenger flights. Examples include Class 3 flammable liquids in large drum containers, Div 2.1 flammable gases in bulk, and standalone lithium ion batteries (UN 3480).
Acceptable on Passenger Aircraft: Strictly packaged dangerous goods within conservative net quantity limits (e.g., consumer commodities, dry ice for biological samples, life-saving medical isotopes) stowed in accessible or Class C cargo compartments equipped with built-in smoke detection and Halon fire extinguishing systems.
4. Information to the PIC and Operational-Control Personnel
§ 175.33 requires accurate, legible written information for the PIC and dispatcher or other operational-control ground personnel as early as practicable before departure, no later than aircraft movement under its own power . The required information includes flight date, air waybill number when issued, material identity/classification, packages and quantities, loading location, cargo-only status, unloading airport, applicable permit/exemption information, and the monitored contact for obtaining this information. The regulation includes specific commodity alternatives and exceptions, including dry ice and certain lithium battery shipments.
The § 175.33(a)(11) monitored telephone contact for shipment information is not identical to the separately applicable emergency-response telephone requirement under Part 172. Emergency-response information must be readily available to the PIC and dispatcher in flight. The PIC acknowledges receipt in writing; loading personnel provide the required indication of no evidence of package damage or leakage.
Retain information to the PIC for 90 days at the departure airport or principal place of business. Shipping papers ordinarily have a one-year carrier retention period, with three years for hazardous waste . Keep the required documents accessible during flight at departure and intended arrival and promptly available to authorities/emergency responders as prescribed. These hazardous-material records rules must not be confused with the three-month Part 121 dispatch-document rule.
- 5. High-Risk Commodities: Dry Ice & Lithium Batteries
- Dry Ice (Carbon Dioxide Solid, UN 1845)
Dry ice is widely used as a refrigerant for pharmaceuticals, perishable organs, and vaccines. At ambient temperatures and flight pressures, solid carbon dioxide sublimes directly into gaseous C O 2 CO_2 C O 2 :
Asphyxiation Hazard: Sublimed carbon dioxide gas is heavier than air, settling into low areas of cargo compartments. If cargo door seals allow gas migration into passenger cabins or the flight deck, crews experience hypercapnia, drowsiness, cognitive impairment, and asphyxiation.
Operational Limit: Every aircraft type has a maximum allowable dry ice loading limit determined by the environmental control system (ECS) airflow rate (measured in pounds per hour of fresh air circulation). Dispatchers must verify that total dry ice aboard does not exceed the structural and ventilation limits documented in the carrier's weight and balance manual.
Lithium Batteries (UN 3480, 3481, 3090, 3091)
Lithium battery thermal runaway represents one of the most severe fire threats in commercial aviation. Once an internal short circuit or physical defect initiates thermal runaway, cell temperatures can exceed 600 ∘ C 600^\circ\text{C} 60 0 ∘ C ( 1 , 100 ∘ F 1,100^\circ\text{F} 1 , 10 0 ∘ F ), generating flammable toxic gases that cannot be extinguished by standard cargo Halon 1301 fire suppression systems:
Lithium Ion (Rechargeable - UN 3480): Standalone lithium ion cells are forbidden as cargo on passenger-carrying aircraft . When shipped on cargo aircraft, cells must be maintained at a State of Charge (SoC) not exceeding 30% of their rated capacity.
Lithium Metal (Non-Rechargeable - UN 3090): Standalone lithium metal batteries are forbidden as cargo on all passenger aircraft worldwide.
Equipment Packaging (UN 3481 & UN 3091): Batteries packed with or contained in equipment are permitted under strict watt-hour limits ( ≤ 100 Wh \le 100\text{ Wh} ≤ 100 Wh for consumer devices) and drop-tested protective packaging.
6. Airline Certificate Policies: Will-Carry vs. Will-Not-Carry
Every Part 121 air carrier operates under explicit FAA Operations Specifications ( OpSpecs A055 ):
Will-Carry Airlines: Authorized to accept, handle, and transport declared commercial hazardous materials. These operators maintain certified dangerous goods acceptance agents, load inspectors, specialized cargo segregation charts, and advanced dispatch monitoring software.
Will-Not-Carry Airlines: The certificate holder's OpSpecs forbid the acceptance or carriage of commercial hazardous materials. However, a 'Will-Not-Carry' designation does not exempt the carrier from regulatory oversight.
The Undeclared HAZMAT & COMAT Requirement
Even a 'Will-Not-Carry' carrier must implement an FAA-approved Hazardous Materials Recognition Training Program . Flight dispatchers, gate agents, and baggage handlers must be continuously trained to recognize suspicious passenger luggage (e.g., camping stoves with fuel residues, fireworks, unauthorized hoverboards) and prevent undeclared dangerous goods from reaching the aircraft.
Furthermore, all airlines transport Company Material (COMAT) . Replacement aircraft parts, such as chemical oxygen generators, engine fire extinguisher squibs, main aircraft batteries, and fuel control units, constitute hazardous materials and must be processed under full dangerous goods compliance.
- 7. Practical Traps & Operational Scenarios
- Practical Trap: Dispatcher Inflight Emergency Role
During an inflight emergency involving fire, smoke, or a cabin pressurization failure, the flight crew's immediate cognitive bandwidth is fully absorbed by flying the aircraft, running abnormal checklists, and communicating with ATC. Under FAA orders, Air Traffic Control will contact the flight dispatcher to retrieve dangerous goods information. The dispatcher must instantly access the electronic NOTOC and provide ATC with the exact UN numbers, proper shipping names, hazard classes, quantities, and cargo compartment locations to relay to Airport Rescue and Firefighting (ARFF) teams prior to landing.
Operational Scenario: Lithium Battery Rejection
A fictional freight forwarder offers standalone lithium-ion batteries (UN 3480) as ordinary cargo for a scheduled passenger flight. Their cargo-only restriction must be checked under the applicable hazardous-materials table and § 173.185 requirements, not inferred from a passenger-information rule such as § 175.25. The dispatcher coordinates refusal/removal and reporting through qualified dangerous-goods personnel and carrier procedures. Passenger-carried devices or batteries packed with equipment have different classifications and conditions; do not interchange them.
Official References
Source check: 2026-10-12 . Hazardous-material carriage ; Dispatcher duty § 121.465 ; Emergency authority § 121.557 ; NTSB Part 830 ; Operator security Part 1544 . For operational use, apply current issued authorizations and the assigned aircraft’s approved data.