New report: 40% rise in lithium-ion battery incidents in air cargo in five years

UL Standards & Engagement released a new report showing an alarming 40% increase in lithium-ion battery incidents in air cargo since 2021, underscoring that the safety risks posed by these batteries threatens to grow alongside rising consumer demand.

The findings are informed by reports shared by airlines in ULSE’s Thermal Runaway Incident Program database, and interviews and focus groups across the cargo supply chain — cargo airlines, regulators, manufacturers, freight forwarders, e-commerce stakeholders, and small and individual shippers worldwide — that offer insight into operational gaps and oversight blind spots. The report examines why thermal runaway events continue to increase, where risk enters the supply chain, and how fragmented and inconsistent supervision leads to unsafe shipments moving undetected across borders.

“Lithium batteries power modern life, but they also present a growing and preventable risk in air cargo,” said Bob McClelland, transportation safety lead at UL Standards & Engagement. “The rise in incidents is not random — it reflects identifiable gaps in battery quality, shipper awareness, regulatory oversight, and supply chain accountability. These are systemic weaknesses that can and must be better addressed if we want to reverse this troubling trend.”

Key takeaways from the report include:

• Thermal runaway incidents in cargo continue to rise alongside consumer demand for low-cost, battery-powered products. Thermal runaway incidents in cargo continue to rise, with a 40% increase since 2021.
• Battery quality and shipper behavior are the core drivers of risk. Small and individual shippers often lack hazardous materials expertise and rely on carriers to catch errors, shifting responsibility downstream. Limited oversight and uneven enforcement leave cargo airlines managing risks they did not create — and often cannot fully see.
• Geography is a predictor of cargo risk. With significant differences in manufacturing quality, regulatory oversight, and enforcement rigor across regions, a battery’s country of origin can be an indicator of a heightened threat. More than half of known-origin incidents begin in a handful of Asian airports — as do a significant number of battery shipments — contributing to industry perceptions that geographic disparities amplify other risks such as battery quality, shipper behavior, and third-party involvement.
• The system is built on trust — and just as equally on plausible deniability. Batteries pass through multiple stakeholders, each relying on the previous one to comply with safety rules. This fragmentation diffuses accountability, making it difficult to pinpoint responsibility or implement lasting solutions when incidents occur.

The report offers three priority recommendations to improve cargo safety: establishing clear, enforceable responsibility across the supply chain; strengthening education and global industry coordination to reduce ambiguity and prevent errors; and treating safety and cost as aligned — not competing — priorities, and drive solutions from the top down.

“In every interview and focus group we conducted, a consistent theme emerged: reducing battery fire risk is a shared responsibility that prioritizes safety as a matter of necessity, not luck,” said Dr. Emily Brimsek, senior manager of qualitative insights.

UL Standards & Engagement is using these findings to support supply chain collaboration and discussions across the industry that lead to safer outcomes in cargo aviation.