Smoke Hoods And Aviation Safety
Brookdale International Systems
A lot has been written about smoke hoods and aviation safety recently, as the subject has been picked up by the mainstream press, but this issue has actually been around for many years. And it continues to be controversial for a number of reasons.
The concept itself is pretty basic. In an aircraft fire the cabin is likely to fill with thick, black, choking smoke and highly toxic gases like sulfur dioxide, hydrogen chloride, hydrogen cyanide, and in particular carbon monoxide. Carbon monoxide, present in virtually all fires, is the lethal compound responsible for most smoke-related fatalities. People who find themselves inside an aircraft under these conditions will not survive for very long, so they must either get out quickly, or be provided with some means to protect themselves until evacuation is possible. Those exposed to smoke, being unable to see or breathe, quickly lose their orientation, are prone to panic, and will become incapacitated in only moments. Smoke hoods are protective head coverings with a filter system that prevent wearers from breathing the smoke, particulates and lethal gases generated in a fire. This might seem like a good idea, as these devices are designed to provide the time needed to survive in this type of deadly environment, allowing safe escape. But the use of smoke hoods, or at least the question of requiring them as standard equipment on passenger-carrying transport category aircraft, has been and remains a highly contentious issue in the aviation community.
Opponents such as the Federal Aviation Administration, the agency responsible for U.S. air safety, contend that passengers taking the time to don the hoods would cause a critical delay in evacuating a burning plane, when each second is truly critical. According to Peggy Gilligan, the FAA’s Deputy Associate Administrator for regulation and certification, ” What you want to do is get people out of the airplane as quickly as possible.” She and other FAA officials have also been quoted as saying that smoke hoods might give passengers a false sense of protection or security. Why the security these devices could potentially provide to passengers would be false is certainly curious, in light of the fact that FAA regulations require this type of protection for flight and cabin crews.
Smoke hood proponents contend that the issue is money. Five years ago the FAA rejected a proposal that it mandate smoke hoods on all commercial passenger aircraft. First put forward in 1987, this proposal was strongly opposed by the Air Transport Association of America, a trade group that represents U.S. airlines. When rejecting the proposal, the FAA cited an ATA analysis that estimated a cost of over $127 million for the industry to install smoke hoods.
“Smoke hoods should be on every airplane around the world” says Mary Schiavo, the former Inspector General of the U.S. Department of Transportation turned aviation-safety advocate. Her view is that the issue of evacuation time is merely a smokescreen for a cost/benefit analysis. “The government figures X amount of people are going to die and their lives are worth $2.7 million, and since the industry says it costs $127 million to do this … I am almost embarrassed as a former government official to explain how it works, but what it takes is a loss of life in dollar value equal to the cost of the equipment.” The sad fact, according to Schiavo, is that it will take a catastrophic air disaster to change the FAA’s policy on smoke hoods for passengers.
What cannot be debated is that aircraft smoke/fire emergencies have always been a serious problem. According to a former U.S. Civil Aeronautics Board investigator (the CAB was the forerunner of the NTSB), there were at least 250 transport-category aircraft accidents involving fire between 1964 and 1994. Technical and safety advancements notwithstanding, the problem still exists. FAA statistics reveal that there is currently “an unscheduled landing of a commercial aircraft on average more than once a week” in the United States due to smoke and/or fire situations. The aviation community is very fortunate that the vast majority of these incidents
do not become accidents, although there have been a number of tragic exceptions. Below is a short list of just a few of them:
1983 — an Air Canada DC-9 made an emergency landing in Cincinnati, Ohio after a fire broke out in a lavatory. Evacuation was attempted, but 23 of the 46 on board were overcome by the smoke and did not make it out of the aircraft.
1985 — Manchester, England. A Boeing 737 developed an engine fire on takeoff. The cabin filled with smoke, and in the course of a panic-filled evacuation 48 passengers succumbed to smoke inhalation.
1989 — a United Air Lines DC-10 crash landed near Sioux City, Iowa. Of the 111 people who died, 37 were victims of smoke inhalation.
1991 — a USAir Boeing 737 collided on the runway with a commuter aircraft. In the ensuing fire there were 34 casualties aboard the 737, 22 resulting from smoke inhalation.
the 1996 ValuJet crash, the 1998 SwissAir disaster, and this week’s crash of an American Airlines MD82 in Little Rock, Arkansas, are the most recent serious fire-related incidents.
There can also be no doubt about the toxic nature of smoke generated in aircraft fires, nor of the effectiveness of properly-designed smoke hoods in protecting against its lethal effects. The subject has certainly been looked at in depth. The British Medical Journal and The Journal of Toxicology, for example, have published a number of scientific articles in this area dealing with topics like “The Management Of Aircraft Passenger Survival In Fire”; “Behavioral Impairment In Smoke Environments”; “Acute Inhalation Injury”; “In-Flight Cabin Smoke Control”; “Making Air Crashes More Survivable”; and “The Toxicological Examination Of The Victims Of The British Air Tours Boeing 737 Accident At Manchester In 1985.”
A recent study by the European Transport Safety Council (ETSC) concluded that smoke hoods should be provided in all commercial aircraft. Referring to the debate over the benefit of respiratory protection versus evacuation time, the report said, “… it seems reasonable to say that smoke hoods might lead to some delay in starting the evacuation. However, this does not have necessarily any detrimental effect. As the House of Commons Transport Committee in its report on aircraft cabin safety concluded: ’It is no use passengers being able theoretically to evacuate an aircraft in 60 seconds if, in toxic smoke and without a smoke hood, they collapse unconscious in half that time. The possibility that it may take 10 seconds longer to evacuate with a smoke hood on is of little consequence if indeed passengers can actually evacuate in 70 seconds from a cabin full of toxic smoke and live to tell the tale.” And all this assumes a fire aboard an aircraft already on the ground. What of a smoke emergency that occurs in-flight, when it may take 12 or 15 minutes to land? Donning time would certainly not be an issue here, and a smoke hood might offer the only possibility of survival. Hardly a “false sense of security.”
The technology of smoke hoods themselves has progressed to the point where small, light and simple to use models are currently available. High quality smoke hoods are generally constructed of heat resistant material like Kapton, which is good to 800F. But the most important part of a smoke hood isn’t the hood itself, but the filter that provides protection from the toxic byproducts of combustion. Virtually all smoke hood designs utilize some form of activated charcoal filter to screen out corrosive fumes like ammonia and chlorine, as well as acid gases like hydrogen chloride and hydrogen sulfide. But the defining characteristic of an effective smoke hood is the ability to convert deadly carbon monoxide to relatively harmless carbon dioxide through a catalytic process. Those that do not protect against carbon monoxide are essentially useless.
As smoke hoods’ role in aviation safety gets increasing attention in the media — support from safety advocates like Ralph Nader; a strong endorsement in Mary Schiavo’s best-selling book “Flying Blind, Flying Safe” that led to a TIME magazine cover story and an appearance on Oprah; a major article on aviation safety in Consumer Reports; a feature story by Associated Press; many newspaper and television news stories and consumer reports — more and more individual consumers are making the decision to protect themselves, since the regulators and the industry are not. They are purchasing their own smoke hoods to take with them when they fly.
The debate continues, positions are taken and held. But it’s interesting to note how the corporate world has reacted to the concept of smoke hoods and aviation. Some 300 of the Fortune 500 companies are sufficiently convinced about the potential safety benefits this type of safety device represents that they have equipped their corporate aircraft with smoke hoods. And the U.S. Air Force has purchased over 34,000 of them.
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