The rules around flying with portable batteries are becoming more confusing as some airlines and governments change their policies, citing the risk of fires.

Southwest Airlines is the first of the four biggest US carriers to tighten its rules, citing incidents involving batteries on flights across airlines. Starting Wednesday, it will require passengers to keep portable chargers visible while using them.

Airlines in Malaysia, South Korea, Taiwan, Thailand, Singapore, and Hong Kong have also either changed their rules in a similar way or banned the use of portable chargers in flight since a fire destroyed an Air Busan plane on the tarmac in South Korea in January. It was one of several recent aviation episodes that made travelers anxious.

There is no definitive link between portable batteries and the Air Busan fire, and an investigation is underway.

Because rules vary across airlines, you might find yourself having to repack or turn off batteries when boarding a plane. Here’s what you need to know.

Which airlines have changed their rules and why?

Southwest passengers will not be allowed to charge devices while they are stowed in overhead bins. The rule will help flight attendants act more quickly if a battery overheats or catches fire, Southwest said in a statement.

The US Federal Aviation Agency requires only that devices containing lithium-ion batteries are kept in carry-on baggage, and the European Union’s aviation regulator has similar rules.

Rules vary among Europe’s biggest carriers. Ryanair, a low-cost Irish airline, tells passengers to remove lithium batteries before storing bags overhead. Britain’s EasyJet and Germany’s Lufthansa do not.

The South Korean government now requires that passengers keep portable chargers within arm’s reach and out of overhead bins, saying that the rule was implemented to ease anxiety about the risk of battery fires.

Malaysia Airlines, the country’s flag carrier, has banned using and charging power banks, and storing them in overhead bins. Hong Kong’s aviation regulator has put a similar regulation into effect for all of the territory’s airlines, including Cathay Pacific.

Major Taiwanese airlines implemented similar changes after the Air Busan episode. EVA Air and China Airlines announced a ban on using or charging power banks on their planes, although the batteries can still be stored in overhead compartments.

Thai Airways, Thailand’s flagship airline, said it would implement a similar ban on using and charging power banks, citing “incidents of in-flight fires on international airlines, suspected to be linked to power bank usage”. Singapore Airlines and its budget subsidiary, Scoot, also announced new rules.

Since 2016, the International Civil Aviation Organization, which is the United Nations agency that coordinates global aviation regulations, has banned lithium-ion batteries, which are the kind commonly found in power banks, from the cargo holds of passenger planes.

But there is no industry standard on how airlines regulate power banks, said Mitchell Fox, director of the Asia Pacific Center for Aviation Safety.

They have become a part of everyday life only in recent years, and some consumers may be unaware of the risks, he said.

What risks do these batteries pose?

Lithium-ion batteries have been used for decades to power smartphones and laptops, and are commonly used in portable power banks.

Each battery has a cell that can heat up quickly in a chain reaction that causes it to catch fire or explode. The FAA warns that this reaction can happen if the battery is damaged, overcharged, overheated or exposed to water. Manufacturing defects are another potential cause.

Some products that use lithium-ion batteries, including smartphones, laptops and electric vehicles, have strict regulations and quality control standards, said Neeraj Sharma, a professor of chemistry at the University of New South Wales in Sydney who studies batteries. Others, such as power banks, e-cigarettes, e-bikes and scooters, are less regulated, he said, raising the risk of malfunction.

“Make sure you get your devices from reputable manufacturers,” Sharma said.

How often do batteries catch fire on planes?

The frequency of incidents involving lithium-ion batteries on US airlines has been increasing. There were 84 last year, up from 32 in 2016. These included cases – in the cabins of both passenger and cargo planes – where batteries caught fire, emitted smoke or overheated. Portable chargers were the biggest culprit, followed by e-cigarettes, according to the FAA.

For years, airlines around the world have required passengers to pack spare lithium-ion batteries in their carry-on luggage instead of in their checked bags so that any smoke or fire from the batteries can be noticed quickly. In the cargo hold, a fire might not be detected by a plane’s automatic fire-extinguishing system until it has become a critical problem.

What do flight crews do when there is a fire?

Fires in plane cabins that are caused by lithium-ion batteries are rarely deadly, and flight crews are generally well prepared to deal with them, said Keith Tonkin, managing director of Aviation Projects, an aviation consulting company in Brisbane, Australia.

In many cases, passengers will notice that their electronics are overheating and inform crew members, who put the device in a thermal containment bag or water, with little disruption to the flight, according to the FAA. – ©2025 The New York Times Company

This article originally appeared in The New York Times.