Posters found at any airline ticket counter identify typical hazardous materials: explosives, compressed gases, flammable liquids and solids, oxidizers, poisons, corrosives, loaded firearms, and radioactive materials. Examples include paint, lighter fluid, fireworks, bottled oxygen, tear gas, and radiopharmaceuticals. The posters also warn of a $25,000 fine per violation and criminal penalties up to $500,000 and five years in prison.
While the regulations governing the transportation of hazardous materials pertain to commercial operations, they have safety implications for all pilots. The regulations for transporting hazardous materials are found in the Code of Federal Regulations: Title 49 CFR 171 through 180. Part 175 states that "hazardous materials that are not prepared for shipment in accordance with this subchapter may not be accepted for transportation or transported aboard an aircraft." Included in Part 172 is a table that identifies specific items that fit the government definition of hazardous materials.
Some 40 pages long, the table documents an entire chemistry lab of substances from seed cake to rocket motors. While these items may seem exotic, a great number of these substances can be found in your own home. The table describes the classification of the material, appropriate label codes, stowage requirements, and other limitations. Some materials such as gasoline, paint, proponal, ammonia, and batteries can be transported in limited amounts with the proper packaging, handling, and stowage. Others, such as lighter fluid, pesticides, and liquid petroleum products are totally forbidden on passenger-carrying aircraft.
The risks posed by hazardous materials are generally obvious. Fumes from fuels and solvents can be both toxic and explosive, especially in the closed environment of an airplane. Batteries containing acid are potential hazards. If a battery shorts out, the heat can start a fire. Spilled acid can damage the aircraft and its occupants. Corrosive materials can damage electrical insulation and aircraft control cables.
The regulations do provide specific exemptions for persons carrying hazardous materials in their personal possession. Up to 70 ounces of medicinal and toiletry articles can be exempted. An individual can legally carry a butane lighter (but not a lighter with lighter fluid), some nail polish re-mover, a flammable spray aftershave, and other generally innocuous personal items. But can even small amounts of hazardous materials, like my can of wasp killer, cause a problem?
Incident Reports
There are few documented cases of hazardous materials accidents and incidents involving general aviation aircraft, but a few dozen reports in the NASA Aviation Safety Reporting System files illustrate the potential risks to pilots and passengers of all aircraft.
Some hazardous materials can be debilitating to pilots when fumes invade the cockpit. One report describes a strong odor like turpentine that developed during a flight. One pilot of the aircraft felt dizzy and sick, and had to be treated at the hospital for potential liver damage. The culprit was a container of xylene that had leaked.
In a similar report, a passenger carried a jar of insect repellent that sounded suspiciously like my wasp and hornet killer aboard an airplane. The jar leaked and generated toxic fumes, and the aircraft had to return to the gate and evacuate passengers. Yet another report tells of a large bottle of nail polish remover that leaked in a passenger's bag, causing a very strong acetone smell in the cabin. The flight crew declared an emergency and landed the aircraft. Flight attendants and passengers were treated at the hospital.
Gasoline is one of the potentially hazardous materials that can be transported in limited quantity (up to five liters) if it is properly packaged, handled, labeled, and stowed. But just because a material can legally be transported doesn't mean it's a good idea to have it on board, as the following reports illustrate.
One incident involved the crew of a light transport turboprop that was flying in Hawaii. The flight had just departed and leveled off at 9,000 feet when the crew noticed what seemed to be toxic fumes in the cockpit. Later the culprit would be found-an improperly packaged pump containing gasoline that had leaked. The crew donned oxygen masks and diverted for an immediate landing, but had to take off their masks to talk on the radio. In his report, the captain wrote, "We descended through a cloud layer and made a visual approach and landed at Kahului Airport. The workload in the cockpit seemed extremely taxing." After landing, the crew was taken to the hospital and treated with oxygen. The captain's report continued, "After about an hour of breathing the oxygen we began to 'come to' and realized how serious a situation we had been in. I don't think we were actually incapacitated, but it was clear to us that we were not performing well at what should have been routine tasks."
In another case, about a gallon of gasoline leaked from a container in a cargo hold. A local hazardous materials response team measured the fumes at explosive levels. In the cockpit of a small general aviation aircraft, even a small gasoline spill could be a potential bomb waiting for the slightest spark to set it off.
Unsuspected Hazards
Not all hazardous materials are identified in the regulations. Pilots must be constantly on the lookout and aware of potential hazards from unsuspected sources. Remember that the boiling point of liquids decreases with pressure, so a thermos of hot coffee, soup, tea, or other beverage may violently boil over when opened at altitude.
Another report from the ASRS files tells of a passenger flying from France to the United States who shared some important safety information. The passenger said he had intended to carry a thermos containing dry ice on the flight. The night before, he put the thermos bottle with dry ice in his refrigerator. Several hours later, the thermos violently exploded, tearing the door off his refrigerator and causing serious damage to his home. The regulations allow quantities of up to five pounds of dry ice to be carried aboard aircraft, but they don't even hint at the potential hazard of carrying that dry ice in a sealed container. As the dry ice sublimates, tremendous pressure builds up if it is in a closed container. In this case, the pressure created a virtual bomb.
Identifying the Suspects
There are several ways to identify potential hazardous materials. The first is by a label on the package. Labels indicating toxic substances, flammable liquids and solids, explosive materials, compressed gas, or other such dangerous goods should be left on the ground.
Another approach is to consult the list of hazardous materials contained in the regulations (see sidebar). Materials are listed in alphabetical order, and both scientific and common names can be found or cross-referenced. If the label of a suspect material suggests a potential hazard, look at the specific contents or active ingredients, and check these against the list.
If you don't have a copy of the regulations and a specific label is not displayed, some common sense will go a long way. A statement that reads "Warning. Irritant. Use in well-ventilated area. May cause dizziness, nausea, vomiting?" is a clear indication that the material is potentially hazardous, and the conscientious pilot will consider some other means of delivering such goods to their destination.
Considering the reports from pilots who have seen for themselves the serious problems that hazardous materials can create, I think I'll roll up my sectional and deal with the wasp at close range. After all, if I miss, it only stings for a few seconds.
Where To Find The Hazmat Regulations
Most commercial versions of the federal aviation regulations and Aeronautical Information Manual don't contain the hazardous materials regulations. The applicable regulations, Title 49 CFR 171 through 180, can be found on the Department of Transportation's hazardous materials Internet site (http://hazmat.dot.gov). To access the hazardous materials table, click on "Rules and Regulations," then on "49 CFR Parts 100-185," and finally on "Hazardous Materials Table."
Who Is Regulated?
The hazardous materials regulations apply to anyone engaged in air commerce, regardless of which part of the federal aviation regulations they operate under (Part 91, Part 135, or Part 121). Commercial operators such as airlines and cargo or charter operators, pilots ferrying aircraft, pilots flying for business, or anyone operating in furtherance of a business must abide by the regulations. Those exempt from the regulations include pilots flying for pleasure.
