AT A GLANCE
- Drawing on data from UL Standards & Engagement’s Thermal Runaway Incident Program (TRIP) and global passenger surveys, this third annual report shows thermal runaway incidents rose 15% overall in 2025 to an average of 2.36 per week. Portable charger incidents jumped 42%, overtaking e-cigarettes as the primary cause of onboard events.
- Nearly 3 in 5 Americans remain unaware that everyday items run on lithium-ion batteries, leading to risky practices like packing power banks in overhead bins. Globally, battery safety concern is highest among Latin American (79%) and Asia-Pacific (83%) travelers,
- Incidents drive significant disruption—12% lead to flight diversions or emergency landings. ULSE estimates thermal runaway events cost commercial aviation ~$1.8 million annually ($7.3 million total from 2021–2024), averaging roughly $96,000 per incident.
- Addressing the trend requires joint action from expanding cabin crew training and onboard fire containment standards to supporting new airline storage policies with clear, continuous passenger education.
Rechargeable Devices Continue to Pose Risk
Rechargeable devices—such as phones, laptops, tablets, and power banks—are essential to everyday life and modern air travel. But as our reliance on rechargeable technology grows, so
does the importance of understanding its risks. Yet, the majority of U.S. adults are unaware that most of the rechargeable devices they use every day are powered by lithium-ion batteries.
In aviation, this awareness gap presents a clear risk. If damaged, improperly charged, poorly manufactured, or counterfeit, lithium-ion batteries can enter a process called thermal runaway, which occurs when the batteries overheat, posing serious risks that include fire or even explosion.
Lithium-ion battery fires burn with intense speed and heat, which can potentially cause significant and widespread damage within seconds. They can also be more challenging to extinguish compared to fires involving other materials. And at 30,000 feet, responding to such an event becomes significantly more complex.
KEY TAKEAWAYS
Hover over each stat below to learn more about the report findings.
Thermal Runaway Incident Rates and Trends
In 2025, there was a 15% increase in thermal runaway incidents on passenger planes, from 107 in 2024 to 123 in 2025. This increase can be partially attributed to the growth in airlines participating in the TRIP program but is also reflective of a long-term trend that shows consistent increase over time. Thermal runaway events rose from 2.05 incidents per week in 2024 to 2.36 incidents per week in 2025 on passenger planes.
“Every incident is a safety risk, and the trend line is moving in the wrong direction. Passengers do not need to be safety experts to reduce the risk. Keeping rechargeable devices within reach can help us all fly in safer skies.”
–Jeff Marootian, President and CEO of UL Standards & Engagement
Among the common types of devices carried on board by passengers, some are more significant potential contributors to thermal runaway incidents than others. Portable chargers were responsible for the most incidents in 2025, with 30% of reported incidents attributed to these devices on passenger flights.
Insight: Passengers Perceptions
28%
of passengers would never fly an airline again if a major thermal runaway incident occurred on one of its planes
34%
of passengers report they are less willing to fly because of awareness about thermal runaway incidents on flights
45%
of respondents say they are concerned about their own devices overheating
51%
of respondents say they are concerned about other passengers’ devices overheating
Insight: Packing Practices Reveal Troubling Behavior
39%
of passengers admit to putting lithium-ion powered products in their checked luggage.
54%
of portable chargers are in checked luggage or the overhead compartment, not within arm’s reach.
35%
of respondents report packing e‑cigarettes in checked luggage
47%
of respondents report traveling with laptops out of arm’s reach.
How to Educate Passengers
Passenger education can significantly help reduce the threat of thermal runaway. Communicating best practices on how and where to pack rechargeable devices needs to happen before passengers arrive at the airport.
Among U.S. passengers 39% said they would prefer to receive lithium-ion battery safety information during booking, and another 31% said they would favor email (ideally through some simple dos and don’ts). This type of straightforward guidance would be most effective according to 88% of passengers.
Clarity also matters. A large majority (80%) of passengers want airlines to clearly communicate lithium-ion battery safety measures.
KEY Themes
Explore feedback from both flight attendants and passengers.
Limited awareness: “When I’m in the airport everything is a blur. I don’t pay attention to the signs.”
-Passenger
Motivation through safety:
“Most people will look into
something that can cause them harm during their flight.”
-Passenger
Uneven emphasis: “Liquid restrictions are heavily stressed, while lithium-ion battery rules are not.”
-Passenger
Insight:
Global Data Shows That Low
Awareness May Further Flight
Disasters Globally
Global differences in lithium-ion battery safety awareness, concern, and behavior suggest that aviation safety communications may be more effective when tailored by geography.
Latin American and Asia-Pacific travelers report higher concern about thermal runaway in aviation. In the first-ever inclusion of global data in the TRIP report, ULSE found that Latin American (79%) and Asia-Pacific (83%) travelers reported higher levels of concern about battery safety onboard and are more supportive of additional safety measures compared to Europe (74%) and North America (67%).
Global awareness of lithium-ion battery hazards remains dangerously low, with at least a quarter of travelers worldwide incorrectly packing portable chargers in checked bags.
Additionally, round two-thirds (65%) of travelers across the board recall lithium-ion safety announcements, but there is a disconnect between when travelers notice these announcements, and when they would prefer to receive them. Typically, these messages are seen or noticed when passengers are moving through security checkpoints. However, most travelers would prefer to receive lithium-ion battery safety information during booking, including 34% of North Americans, 27% of Europeans, 25% of Latin Americans, and 19% of Asia-Pacific travelers.
KEY Insights
Hover over to explore global insights from our data.
More than 3 in 10…
…Travelers worldwide don’t know what lithium-ion batteries are.
At least 25%…
…Of travelers around the globe are creating potential risks through their packing decisions.
More than 8 in 10…
…Travelers worldwide would support even more battery safety messages from airlines.
Reversing the Trend
With more lithium-ion battery-powered devices carried on board by passengers, the corresponding increase in thermal runaway incidents is unsurprising. Unsurprising does not mean acceptable. Our research reveals three recommendations to help reverse the trend.
- Passenger education: Most passengers do not know about best practices for packing and handling lithium-ion battery powered devices. Education can make a difference, even if the message is simply to keep rechargeable devices within arm’s reach.
- Cabin crew training: All cabin crew are trained to respond to thermal runaway incidents on board an airplane. However, cabin crew self-identified gaps in their understanding of thermal runaway events and the appropriate order of operations when addressing these fires. The recommendations that emerged include the following: Training design and procedures should be closely linked to available safety equipment, should be evaluated and revised based on emerging risks, and should replicate common, real-world scenarios. Additionally, planes should be equipped with the appropriate safety equipment in the correct locations.
- Standards for aircraft and baggage handling: To help mitigate potentially catastrophic incidents, ULSE publishes standards that address the risks and hazards of thermal runaway. These standards include UL 5800, Battery Fire Containment Products; UL 5840, Electrical Systems of Battery Powered Aviation Ground Support Equipment; and the forthcoming UL 5810, Active Fire Protection for Air Cargo Containers.
LEARN ABOUT UL 5800 & Battery Fire Containment Devices →
Download the full report to see more data and details about thermal runaway in aviation incidents in 2025, as well as strategies to reduce the risk, methodology, and additional insights.
Ready to Learn More?
Ready to Learn More?
Learn About The
Thermal Runaway Incident Program
UL Standards & Engagement leads the Thermal Runaway Incident Program (TRIP), a voluntary reporting system designed for the aviation industry to better understand the extent of the problem and prepare for — or, ideally, prevent — future incidents.
Participants from 37 passenger and cargo airlines provide detailed information on incidents within their operation. The information is anonymized and shared with aviation industry and safety organizations, offering insights to improve the safe transport and usage of lithium-ion battery-powered goods. The TRIP database operates as a surveillance tool, designed to capture data on the frequency, characteristics, and consequences of lithium-ion battery thermal runaway incidents in passenger and cargo operations.
The Federal Aviation Administration also collect thermal runaway incident data. FAA data is taken from mandatory federal reporting, while TRIP includes additional reports from every stage of the travel process by factoring in incidents in the terminal, bag checking, security checkpoints, and leaving baggage claim.
