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April 10, 2024

The Battery Risk Travelers Are Packing in Their Luggage

Person packing luggage

By: Sayon Deb and David Wroth

As more airline passengers take to the skies, they are bringing more devices powered by lithium-ion batteries with them. From cell phones and laptops to tablets and headphones, these rechargeable products are essential to daily life and the travel experience. They also pose a lesser-known risk to the travelers packing them: thermal runaway. 

We have all had the moment checking in at the airport when we are asked if we have any lithium-ion batteries in our luggage. But UL Standards & Engagement’s recent study revealed that little is known about lithium-ion batteries, making the answers at bag check unreliable — and potentially dangerous.  

These batteries, while efficient and widely used, can present safety hazards if damaged, improperly charged, poorly manufactured, or counterfeit. Unfortunately, more than two in five U.S. adults in our survey said they knew nothing about lithium-ion batteries. Further, 60% of respondents are unaware that many of the tech products they routinely use, including many that are brought on airplanes, are powered by lithium-ion batteries.  

That lack of awareness becomes more complicated at 40,000 feet. 

Packing Risk in Their Checked Luggage 

UL Standards & Engagement has been collecting data on thermal runaway incidents in aviation for five years. In 2023, we saw incidents increase to the highest point in our database’s history. The leading culprit of these incidents is e-cigarettes, responsible for more than one-third of all reported incidents, followed by portable power banks at number two.  

These two products are also the ones passengers are most likely to pack in their checked luggage. Keeping all lithium-ion battery-powered devices within arm’s reach can sharply reduce the risk of an incident occurring. Devices powered by lithium-ion batteries are generally safest in the hands of the owner, in the cabin of the aircraft where the device can be observed for signs of thermal runaway such as heat and smoke. If these signs are noticed early, airline crews have procedures to contain the device and prevent further damage to the aircraft or injury to passengers.  

Reducing Risk Through Passenger Education  

To be clear, these fires are incredibly rare. They are also largely preventable. Passenger education and the use of safety standards are critical tools in reversing the trend of increasing incidents.  

Airlines and airports are actively warning passengers about lithium-ion batteries, but those warnings are too often unseen and unheard. More than half of travelers we surveyed said they either cannot or don’t know if they can recall seeing or hearing safety signage announcements regarding lithium-ion batteries at any point of their travels.  

Where Standards Can Support Aviation Safety 

Even with the most stringent safety policies and effective monitoring, issues can still arise due to damage, misuse, or manufacturing errors, which can cause a battery to enter thermal runaway and ignite. Thermal runaway fires can take off in seconds, far faster than a plane is able to land if an incident happens while in-flight.  

ULSE was approached by representatives of the aviation industry to develop a safety standard for containment products used to suppress lithium-ion battery fires: UL 5800, Battery Fire Containment Products. It is an important part of ensuring that if thermal runaway issues do occur during flight, a potential disaster can be avoided.  

Problem Solving on the Global Stage  

There is still more that we can and must do to protect the safety of flight crew and passengers. UL Standards & Engagement’s Thermal Runaway Incident Program works with 24 passenger and cargo carriers, including the largest in the industry. These TRIP participants voluntarily report incidents to our database. They also participate in program summits that bring the aviation industry together to solve for thermal runaway risks. 

This week, TRIP is broadening its focus and holding its first international summit. In addition to current program participants, we will look to engage new and potential partners in safety from across the globe.  

With committed partners, passenger education, and greater adoption of standards, safer skies — with the battery-powered tech products passengers want to carry — are in our future.


Sayon Deb is director of insights at UL Standards & Engagement and the author of the report, “The Impact of Public Awareness Gaps Around Lithium-Ion Batteries in Air Travel.” David Wroth is director of technology and systems at UL Standards & Engagement and leads the Thermal Runaway Incident Program.