Battery-related incidents on passenger flights continue to rise, with portable chargers now the leading source of thermal runaway events, according to new data from UL Standards & Engagement (ULSE).
The organization’s third annual ‘Lithium-ion Battery Incidents in Aviation: 2025 Data Review’ found that thermal runaway incidents increased 15% from 2024 to 2025, continuing a long-term upward trend since ULSE began tracking the issue.
Portable chargers were the device most frequently involved in incidents, with cases increasing 42% year over year. E-cigarettes, which were the leading device in 2024, rose 26%, while cell phones were the third most common device linked to incidents.
ULSE said the findings are based on data from more than 40 airlines that voluntarily share information through its Thermal Runaway Incident Program, alongside consumer research on passenger awareness and behavior. The 2025 review also includes economic impact data for the first time.
According to the report, the average number of passenger-flight battery incidents rose to 2.36 per week in 2025, up from 2.05 per week in 2024. ULSE estimates thermal runaway incidents on commercial passenger flights caused about $7.3 million in damages and losses from 2021 to 2024, averaging approximately $1.8 million a year, or about $96,000 per incident.
The review also found regional differences in passenger concern. Travelers in Latin America and the Asia-Pacific region reported higher concern about onboard battery safety, at 79% and 83% respectively, compared with 74% in Europe and 67% in North America.
“Every incident is a safety risk, and the trend line is moving in the wrong direction,” said Jeff Marootian, president and CEO of UL Standards & Engagement. “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.”
“Year after year, we continue to see battery incidents rise, underscoring the need for action,” said David Wroth, lead of ULSE’s Thermal Runaway Incident Program. “There is no silver-bullet solution to this growing safety challenge, which is why we’re working across the industry to better understand the risks and identify solutions that can help prevent a serious or catastrophic event.”
The report comes as major airlines, including United, Delta, American and Southwest, continue to introduce policies covering the use and storage of portable chargers onboard aircraft. ULSE said the increase in portable charger incidents reinforces the need for continued passenger awareness and action by airlines, regulators and industry partners.
“Airlines are taking the risk seriously, strengthening policies and training crew to respond when incidents occur,” Marootian said. “But they cannot solve this problem alone. Passengers need to understand the risks and know what to do before the rechargeable device becomes a safety threat.”
