The threat of an inflight fire exists on any flight, at any time. An uncontained fire can lead to the catastrophic loss of an aircraft in minutes, making it one of the most stressful and hazardous situations that a pilot can face during flight.
From the moment a fire warning is activated on an aircraft, according to a Canadian Transportation Safety Board (TSB) study, pilots have only 17 to 19 minutes to get the aircraft on the ground. Any later than this means the chances of survival are highly unlikely.
Once smoke or fire is confirmed, this clock begins to tick. Immediate action is required to land the aircraft as soon as possible. To increase the chance of survival, operators need to provide both pilots and cabin crew with the tools necessary to safely combat this threat.
“The threat of inflight fire and smoke is one of the most visceral threats to flight safety,” said Klatt Works CEO Nathan Klatt. “Historically, smoke in the cockpit has caused aircraft to divert every 12 to 48 hours, globally. By the time smoke has occluded the ability to see cockpit instruments or out the windscreen, problems can be compounding within the aircraft.”
Klatt Works is an emerging innovator focused on improving aviation safety. The company recently certified its Saved (Smoke Assured Vision Enhanced Display) product that uses augmented reality technology to help pilots fly in a smoke-filled cockpit. Klatt added, “The Saved product provides another tool in which flight crew can have a fighting chance of getting their aircraft safely on the ground or ditched.”
The number of these smoke, fire, or fume (SFF) events is on the rise. While the origins of these events vary, a growing number of these incidents are attributed to the proliferation of lithium batteries that power everything from smartphones to electronic vape devices.
Each pilot, cabin crew member, and passenger typically carries at least two electronic devices onboard a flight; each is powered by a rechargeable lithium battery that holds the potential to torch off at 500 deg C (932 deg F).
The FAA first began to collect data on lithium battery fires in 2006. Since then, there have been nearly 500 events reported. The agency acknowledges that these figures include only the reported events. The actual number of lithium battery fires on aircraft in the U.S. is underreported.
According to the FAA, lithium battery fires on airlines are on the rise and occur at a rate greater than 1.4 reported events per week. In 2022, there were at least 74 lithium battery air incidents involving smoke, fire, or extreme heat. In the first three quarters of 2023, there have been 53 verified events—a number that matches the full-year total in 2021.
Data indicates that passenger flights are three times more likely to have a lithium battery fire than cargo flights. This is due to the high number of personal electronic devices powered by lithium batteries. The most common type of device to cause a fire on a flight are batteries or battery packs (40 percent of all incidents), followed by e-cigarettes and vape devices (20 percent). Cell phones, laptops, and other electronic devices account for the remainder of the incidents.
Thermal Runaway
Thermal runaway is a term used frequently in relation to lithium battery fires. A thermal runaway event is a phenomenon where the lithium battery enters an uncontrollable, self-heating state.
According to Coalition of Airline Pilots Associations executive v-p Bob Brown, “Lithium-ion batteries are rechargeable batteries and are capable of overheating. This can lead to thermal runaway, which can cause the sudden release of the battery's contents as a flaming jet, heavy smoke, or unburned hydrocarbons.”
Brown, who serves as the chairman of the federal government’s Lithium Battery Air Safety Advisory Committee, added, “In some cases, the battery can explode or rocket. Once one cell in a battery pack goes into thermal runaway, it produces enough heat to cause adjacent cells to ignite. The resulting fire can flare repeatedly as each cell ruptures and releases its contents.”
In addition to a heavy dose of industry safety work, Brown flies as a Boeing 757/767 captain for a large Part 121 airline. He stressed, “Early recognition of a possible thermal runaway by a crewmember may prevent a potential smoke or fire event. A thermal runaway can manifest in different ways depending on the device, including on-screen warning statements, discoloration of screens, smoking, expanding, or swelling of the device, or simply being hot to the touch.”
Fire in the Cabin
FAA Advisory Circular 120-80B provides guidance on firefighting and handling a high-energy fire caused by a device powered by a lithium battery. The recommendation is to “aggressively pursue” a fire to determine the source of the fire and attack the fire using all available resources.
AC 120-80B also discusses containment products used for firefighting; the devices are often called fire containment bags. There are a number of these products marketed for inflight use. Researchers at the FAA emphasize that the portable electronic device (PED) should be cooled prior to being moved into a containment device and warn of the dangers of picking up a PED in an unstable condition.
In December 2020, Underwriters Laboratories (UL) announced a new standard for fire containment devices. The new standard, UL 5800, includes testing and certification and should reduce the risk of in-flight thermal runaway events in the future.
It is important to note that UL 5800 is the only certified standard for fire containment devices. Many fire containment bags are marketed as “FAA certified” or “FAA tested,” but according to AC 120-80B, the agency does not have any test standards that relate to fire containment devices. The only standard that exists today is UL 5800.
In response to an increase in the number of lithium battery fires on aircraft, the FAA issued Safety Alert for Operators (SAFO) 09013. The SAFO provided an additional warning that relates to handling PEDs with unstable batteries. It warns, “Do not use fire-resistant burn bags to isolate burning lithium-type batteries. Transferring a burning appliance into a burn bag may be extremely hazardous. Do not move the device until you are certain the fire is extinguished, and the device is cool.”
Lithium Fire Guard
Lithium Fire Guard president Andrew Reenstra provides caution on the use of fire burn bags on aircraft, saying, “The industry has become complacent with a burn bag product, of which several exist in various shapes and sizes. The FAA...advises full extinguishment of the battery and fire before placing into a burn bag.” This is due to the risk of an unstable battery causing further harm. "Any movement in that condition could precipitate a further reaction with unknown results," the FAA explained.
According to the company, Lithium Fire Guard is the only fire containment case that is tested and certified under the new UL 5800 standard. Its product, the PG100 PED Fire Containment Case, can contain a lithium battery that is in a thermal runaway condition for hours. The PG100 is sold as a kit that includes the Fire Containment Case, safety glasses, leather welder gloves, and a mechanical “grabber” to pick up the burning device.
“The patented metal case allows for the crew member or passenger who is acting as a firefighter to be protected against explosion and fire by allowing them to stand over the product while being protected behind a clear poly shield. The device can be in any state of fire, explosion, smoldering, and the firefighter is protected nonetheless,” Reenstra explained.
The PG100 is a metal case that contains lithium battery fires, filters toxic smoke, and protects the crew members and passengers against explosion. A high-temperature spring-loaded silicone gasket allows for water to be added once the burning device is secure in the PG100.
Reenstra provided details on some of the testing of the device: “During one of the UL5800 tests, a battery literally shot out of its housing like a bullet. The PG100 stopped the projectile cold while continuing to perform its other duties on fire and smoke.” He added, “I certainly wouldn’t want to be standing over a burning PED without any form of protection against an explosion like that.”
Smoke in the Cockpit
In addition to lithium battery fires, other sources of inflight fires include faulty wiring and circuit protection, electrical and electronic equipment failures, bleed air leaks, and lightning strikes. FAA service difficulty reports identify nearly 900 smoke or fire events in transport category aircraft each year.
At the first indication of an inflight fire or smoke event, pilots must first protect themselves by donning oxygen masks. They then need to communicate with the cabin crew, begin a diversion, and determine the source of the fire. During an actual fire, the situation can become overwhelming to the flight crew in minutes.
Analysis of fatal accidents caused by a catastrophic inflight fire identifies several challenges for the flight crew that involve not only cascading aircraft system failures (thermal damage to the flight controls, electrical systems, oxygen systems, etc.) but also an environment on the flight deck that is filled with dense smoke and toxic fumes.
In one case, the smoke on the flight deck of a Boeing 747 freighter was so thick that, within minutes, it severely obscured the visibility in the cockpit to nearly zero. As a result, the pilots were unable to change radio frequencies (radio located on the center console) and had difficulties manipulating the mode control panel and flight management systems. Visibility outside of the flight deck was impossible due to the dense smoke.
VisionSafe EVAS
VisionSafe managing director Alex Werjefelt understands the hazards of an inflight fire or smoke event and said, “FAA statistics show an average of three incidents of smoke, fire, or fumes happen each day in the U.S. alone and [are] a leading cause of ETOPS diversions.” He continued, “It has prompted the FAA to issue InFO [information for operator] reports, and other notices on the matter urging operators to adopt practices to safeguard against the associated threats. If one were to try and predict what could cause the next accident, statistics would show that smoke, fire, and fumes would likely rise to the top of what would be a contributing factor.”
VisionSafe has deployed thousands of its FAA-certified Emergency Vision Assurance Systems (EVAS) around the globe. To date, EVAS has been installed in more than 4,000 aircraft including corporate, airline, and cargo aircraft. According to the company, nearly 70 percent of all cargo jets fly with EVAS, including “blue chip” companies like FedEx, UPS, Cargolux, Atlas, and many others.
EVAS is a self-contained device that provides a clear space of air through which a pilot can see flight instruments and out the front windshield for landing. At the first indication of fire or smoke, each pilot readies the device by pulling it out of its container and positioning it on the glare shield. When needed, pilots activate the system, and the inflatable vision unit (IVU) inflates with one lobe above the glare shield to see outside the aircraft and another lobe below to view the flight instruments. Pouches are provided on each side of the IVU to view checklists and approach plates.
Operators routinely train with EVAS in the simulator to provide pilots with the confidence in using the device in a real-life situation. According to VisionSafe’s Werjefelt, having EVAS installed on an aircraft relieves stress in a big way. “From those who have armed EVAS during smoke events, even if they did not do a full deployment, they said their stress and sense of panic was reduced by knowing that if the conditions became worse, they had a solution for the problem.”
Werjefelt continued, “EVAS allows pilots to maintain a view of instrumentation, checklists, and out the windshield should smoke in the cockpit become blinding, to guide them to a safe landing. We have had major airline pilots come to us with harrowing stories, some having had multiple blinding smoke events where they couldn't see anything. These pilots have become adamant about supporting efforts to get EVAS on their fleets. Ultimately if a pilot can’t see, he can’t fly. Sight is the most fundamental aspect of safe flight.”
Klatt Works Saved
Klatt Works recently developed and certified another tool to combat inflight smoke and fire events. The Saved viewing system is integrated within the pilot’s full-face oxygen mask and goggles to help pilots navigate with a smoke-filled flight deck. Saved uses augmented reality (AR) technology to display critical flight information directly on the goggles using head-up display symbology and exterior views of the aircraft from a camera mounted on the nose of the aircraft. Saved is viewable in all lighting conditions. In the absence of smoke, the system is turned off and stowed out of the normal field of view so the pilot can continue using the oxygen mask.
According to CEO Klatt, “The Saved product displays nose-cam video with HUD symbology, allowing the pilot and copilot the ability to continue to aviate in a very bad smoke-in-the-cockpit situation. The system can be rapidly employed within five seconds of donning the oxygen mask, and the displays can be turned off in a see-through mode as the situation changes within the aircraft.”
Klatt Works teamed with FedEx to develop Saved and has been jointly working on the system for over two years. The FAA recently awarded a supplemental type certificate for the Saved system on the Boeing 777. FedEx plans to equip its 777 freighter fleet with Saved and has plans for future STCs on the Boeing 757 and 767.
According to Klatt, “We are proud to be a part of this solution contributing to a safer future for aviation.”
The threat of an in-flight fire or smoke event is a growing problem in aviation. Multiple industry efforts are in play to help mitigate the threat of an in-flight smoke or fire event and to prevent each event from escalating into an uncontained fire with catastrophic consequences. The threat is obviously real, and more operators need to pay attention to the developments in technology that aim to protect their flight crew and passengers from smoke and fire events.