It begins with an issue that has been smoldering literally at times within aircraft cabins: lithium-ion batteries. On Sept. 25, Southwest Airlines will be the first large U.S. carrier to ask passengers bringing lithium-powered mobility aids, like electric wheelchairs and scooters, to take out the batteries prior to checking the device. Those batteries would have to be brought into the cabin, where attendants can observe them and access them easily should something happen.
The airline is setting the maximum size of allowable batteries at 300 watt-hours, a level that follows International Air Transport Association (IATA) guidelines and reflects limits already imposed on most foreign airlines. A grace period to Jan. 11, 2026, will permit larger batteries to be shipped under the new rules for handling, but beginning on that date, devices above the limit will not be accepted. Dave Hunt, Southwest’s vice president of safety and security, informed employees, “Lithium batteries have become one of the most common sources of smoke and fire incidents on aircraft. While these events are rare, quick access and visibility are critical to keeping everyone onboard safe.”
The shift comes as accumulating data reflects the dangers. In UL Standards & Engagement’s 2024 review, airlines averaged two thermal runaway incidents per week a 15 percent increase since the last five years. Thermal runaway is an internal chain reaction of a lithium-ion cell that can drive temperatures over 1,000 degrees Fahrenheit, generating flammable gases and high heat that can cause nearby materials to burn. The reaction is self-sustaining and notoriously hard to put out, particularly in a confined space.
The Federal Aviation Administration cautions that fire extinguishing systems in cargo holds are not capable of halting a lithium battery fire. To that end, the FAA bans spare lithium-ion batteries in checked luggage and advises passengers to carry battery-powered devices in the cabin. The logic is straightforward: if a piece of equipment starts overheating, flight attendants can use specialized containment bags, halon extinguishers, or water to cool cells before the reaction gets out of control. All that is impossible in the cargo hold.
Recent events prove the risk. In May, a Southwest flight had to divert after a passenger’s portable charger started smoking on board midflight. A KLM flight from Amsterdam to São Paulo was full of smoke in August when a phone charger ignited. And perhaps the most serious instance was when, in January 2025, an Air Busan flight burned an airplane following a lithium battery blaze miraculously without human casualties. These incidents reinforce why airlines are enforcing stricter regulations not only for mobility aids, but also for power banks, e-cigarettes, and other recharging electronics.
Batteries for mobility devices are a special problem. They tend to be larger than batteries for consumer electronics, with larger energy densities to enable longer trips. Although the great majority function safely, their size makes it such that if they fail, the released energy can be large. By forcing these batteries to be taken out and brought inside the cabin, Southwest is guaranteeing that any instances of swelling, heat, or smoke can be handled quickly. The policy also adds that these batteries will not be included in carry-on restrictions, a step taken to prevent penalizing passengers who use mobility aids.
The ULSE report discovered that 38 percent of travelers confess to carrying lithium-powered devices in checked bags, even after safety warnings. That habit, coupled with the reality that almost every traveler carries at least one rechargeable item on board, has maintained the rate of incidents obstinately high. Power banks and e-vapes are the prime suspects, but any lithium-ion cell has the potential to fail under the correct circumstances defects in manufacture, physical abuse, or faulty charging among them.
Southwest’s action precedes its previous May 2025 policy making portable chargers accessible when used in flight, becoming the first major US airline to implement that step. Other airlines, such as American, Delta, and United, prohibit mobility device batteries, though their policies differ in watt-hour limits and treatment procedures. Hunt labeled the new measures as “proactive safety,” adding, “We’re not waiting for a regulator or an outside entity to tell us what to do. We felt there was enough evidence for us to make what are fairly modest changes.”
For frequent flyers who depend on powered mobility devices, the change will require some adjustment removing and carrying a heavy battery through security and onto the plane is no small task. But from an engineering and safety standpoint, it is a calculated response to a documented hazard: keeping high-energy lithium cells within arm’s reach, where human intervention can prevent a minor incident from becoming a catastrophe.
