Thank you everyone for your comments and suggestions from my in-flight electrical fire blog. A few comments of particular note came from pilots advocating the use of fire containment bags in the unlikely event of a lithium-ion battery fire. While I concur that these bags are great for safety, the FAA does not seem to share the same passion for their functionality as many of the enthusiastic companies marketing these bags.
What is a Lithium-Ion Battery Fire?
Rechargeable lithium ion batteries contain multiple cells. These cells are connected in series to produce the desired voltage. For example, iPhone and iPad batteries each have two cells, and laptop batteries can have 6 or more. Lithium-ion battery cells can sometimes overheat, leading to a process called thermal runaway, which can cause the sudden release of the contents of the battery as a flaming jet, heavy smoke, or unburned hydrocarbons. In some cases, the battery can even explode or rocket. Once one cell in a battery pack goes into thermal runaway, it produces enough heat to cause adjacent cells to go into thermal runaway. The resulting fire can flare repeatedly as each cell ruptures and releases its contents. (AC 120-80A)
FAA Recommended Procedures to Fight a Lithium-Type Battery Fire
The following procedures are recommended for fighting a fire in a lithium-type battery-powered personal electronic device. The procedures consist of two phases: extinguishing the fire and cooling the remaining cells to stop thermal runaway.
Utilize a halon, halon replacement, or water extinguisher to extinguish the fire and prevent its spread to additional flammable materials.
Immediate and aggressive action when confronted with a potential fire is much more important than delaying while you attempt to classify a particular fire. Upon discovering a fire, the initial focus should be on aggressively extinguishing the fire with a readily available extinguisher. Generally, you should consider using the first available extinguisher rather than delaying your firefighting efforts while you locate a particular class of fire extinguisher. Keep in mind that unpressurized aircraft should descend at the maximum safe rate to 8,000 feet or the minimum practicable altitude to avoid hypoxia resulting from the agent displacing oxygen from the air and to minimize exposure to halogenated agents. This guidance should be followed regardless of the cabin ventilation rate.
In addition to the aircraft’s fire extinguisher, pilots should also consider those items not normally thought of as firefighting aids. For example, a pilot may pour non-flammable liquid such as coffee, soda, juice, or water onto a fire. When extinguishing a suspected electronic device fire, douse the device with water, an aqueous based extinguishing agent, or other non-alcoholic liquids to cool the device and prevent additional battery cells from reaching thermal runaway. You may use a carbonated beverage as a fire extinguisher by shaking up the can or bottle, opening the top, and spraying the contents at the base of the fire. Any of these suggestions may prove to be effective as possible firefighting methods. These examples are not meant to be all-inclusive; pilots should consider what other items might be useful.
After extinguishing the fire, douse the device with water, an aqueous-based extinguishing agent, or other non-alcoholic liquids to cool the device and prevent additional battery cells from reaching thermal runaway.
Water (as well as other non-alcoholic liquids) can provide sufficient cooling to prevent reignition and/or propagation of the fire to adjacent batteries. Although it may react with the tiny amount of lithium metal found in a disposable battery, water is very effective at cooling the remaining cells, stopping thermal runaway and preventing additional flare-ups. Significant cooling is needed to prevent the spread of fire to additional cells in a battery pack. (SAFO 09013 )
WARNING: Do not attempt to pick up and move a smoking or burning device! In addition, do not stomp on it to attempt to put out the fire! You may be injured.
WARNING: Do not cover the device or use ice to cool the device. Ice or other materials may insulate the device, increasing the likelihood that additional battery cells will reach thermal runaway.
FAA Concerns over Using a Fire Containment Bag
While the Administrator does not object to the use of these containment products provided the procedures follow best practices laid out in SAFO 09013, AC 20-42D, and AC 120-80A, they do NOT endorse any manufacturer procedure that suggests moving a burning, smoking, or hot device.
While manufacturers of certain containment bags may recommend that a pilot move a burning, smoking, or hot device associated with a lithium battery, the Administrator continues to recommend that all crewmembers not move any device that is burning, smoking, or exhibiting any evidence of overheating until that device has been thoroughly cooled. A device that is burning, smoking, or hot is inherently unstable and therefore unpredictable. Any movement in that condition could precipitate a further reaction with unknown results. Therefore, the Administrator recommends continued application of water or other nonflammable aqueous substance for a period of at least 15 minutes after a fire has been extinguished or the smoke has dissipated. A cooled device may then be placed in a receptacle (including a containment product) that will hold water or other nonflammable liquid. (InFO 17021)
The FAA Does NOT Have Fire Containment Bag Testing Standards or a Certification Program
Manufacturers have stated in their advertisement and marketing videos that their products “are FAA certified,” “have been successfully tested by the FAA,” or “meet FAA standards.” However, the Fire Safety Branch of the FAA William J. Hughes Technical Center and the Aircraft Certification Service emphasize that there are no testing standards for these containment products, nor is there a mechanism in place for the approval of these products. (InFO 17021)
How to Use a Fire Extinguisher
Handheld fire extinguishers are designed to be used in the upright position. Most extinguishers have been designed with a center siphon tube that extends to the bottom of the canister. Placing a fire extinguisher on its side or upside down prevents the agent from flowing through the tubing, which has been designed to collect the agent from the bottom of the canister. Laying the extinguisher on its side or turning it upside down to aim at the ceiling may limit the amount of extinguishing agent that is available to be discharged, thereby reducing the extinguisher’s firefighting capacity.
Using a Halon Fire Extinguisher
Generally speaking, halon is not harmful to passengers and crew; however, various publications, including AC 20-42 , caution against exposure to “high levels” of halon in confined spaces, citing the possibility of dizziness, impaired coordination, and reduced mental sharpness.
As a point of reference, NTSB investigations of in-flight fires indicate that crewmembers have been hesitant to use halon extinguishers during flight because of mistaken ideas about adverse effects of halon. In these instances, the crewmembers lost critical time and delayed the aggressive pursuit of the fire. General aviation pilots may want to consider halon extinguishers because they can be used for fighting many fire types and the NTSB determined that extinguishing the fire quickly may be of greater importance than adverse health risks. You should consider how you’re going to handle a fire and what kind of fire extinguisher you want handy now, before an emergency happens.
What You Should Have Learned
Lithium-ion battery fires are highly dangerous because they are a series of fires. Lithium batteries are capable of ignition and subsequent explosion due to overheating. Overheating results in thermal runaway, which is a chemical reaction within the battery that causes the internal temperature and pressure to rise. The best practice to extinguish the fire is to use either a halon or water-based fire extinguisher. Even when the fire is out, continue to add water to the electronic device to cool it so it keeps other lithium-ion cells from igniting. This should be done for 15 minutes, but you should hopefully be safe and on the ground by this time.
Are you prepared for a possible lithium-ion battery fire? Do you carry a containment bag, and are you aware of the current stance the FAA has regarding these bags? Are there ample cooling supplies in your aircraft in the event of a lithium-ion battery fire?
Professional crews consistently train and stay engaged with scenarios that may one day become reality; thus, these crews are more prepared if such a scenario presents itself. In general aviation, we are only so prepared if we seek out this information. Because lithium-ion batteries are a part of the vast majority of general aviation flight decks, we need to ask ourselves how we are going to handle these emergencies.