The Federal Aviation Administration (FAA) issued a safety alert on Tuesday warning of the risk of uncontrollable fires associated with lithium batteries.
Spare lithium batteries are generally prohibited in checked luggage, but even in carry-on baggage, they can malfunction and pose a risk to passengers and crew members.
Lithium batteries are also often found in cell phones, computers, portable chargers, hearing aids and other devices, which can malfunction and create “thermal runaway events,” where pressure and temperature rapidly increase and can ignite a fire onboard.
The FAA said this is particularly dangerous when batteries are not in plain sight.
“Lithium batteries stored in passenger overhead bins and or in carry-on baggage, may be obscured, difficult to access, or not readily monitored by passengers or crewmembers. Because of this, detection of thermal runaway and firefighting measures may be delayed in flight, increasing the risk to safety,” the agency said in its Safety Alert for Operators (SAFO).
The FAA advised airlines to revise its “traditional firefighting methods” to take into account the proper response to thermal runaway events, which require “using large amounts of water to cool the battery and suppress flames.”
While Halon extinguishers can suppress the open flames briefly, they do not stop the rapid spread of energy involved in thermal runaway events.
“Cooling the device with water is essential to prevent the reaction from continuing until all cells have discharged their energy,” the SAFO read.
Aviation officials also advised airlines to revisit its safety material to ensure they’re advising passengers on the best way to handle and store the batteries so they do not get damaged or short-circuit — which can happen when batteries’ exposed terminals touch other metals like coins or keys.
The alert comes as the FAA has recorded an increase in recent years in the number of safety events associated with lithium batteries. In 2025 so far, 50 incidents have been verified and seven were still pending as of Sept. 2.
In 2024, 89 incidents were recorded compared to 77 in 2023. In 2022, 75 incidents were recorded compared to 54 incidents in 2021.
From March 2006 to August 2025, the FAA recorded 648 verified lithium battery incidents, 252 of which were from batteries, 138 of which were from e-cigarettes or vaping devices, 97 of which were from cell phones, 81 were from other electronic devices, 77 were from laptops, and 3 were from medical devices, according to the agency.
