Misplace your phone during a flight and the pilot might turn the plane around.
That’s what happened on a recent Air France flight from Paris to the Caribbean. When a passenger and crew members couldn’t locate a missing smartphone, the cockpit opted to return the plane to the airport it had departed from not long before.
The concern, the airline later explained, was that the unattended phone’s lithium-ion battery could cause a fire. That’s more likely to happen, experts warn, when an electronic device is under pressure—like if the phone becomes wedged tightly between seats and then a reclining seat crushes the device, for instance.
The missing phone on the Air France flight was later found and all the passengers eventually made it to Guadeloupe, albeit 4 hours later than scheduled.
But the pilot was right to be cautious, according to aviation experts who have grown increasingly alarmed by the fire risk posed by lithium batteries, which power pretty much all smartphones (including those made by Apple and Google), laptops, portable chargers, e-cigarettes, digital cameras, smartwatches, and other electronics people travel with.
Growing Concern and Stricter Rules for Flying with Lithium Batteries
Officials in South Korea suspect the lithium battery in a passenger’s power bank sparked a fire on an Air Busan flight shortly before its scheduled departure in January, prompting an evacuation of everybody aboard and causing the plane to be destroyed.
A wave of new restrictions on electronics in airplane cabins has since swept Asia, CNN reports.
South Korea implemented a nationwide ban on storing power banks and e-cigarettes in overhead bins. Instead, passengers have to keep those items under seats or in seat-back pockets. Charging a power bank using your seat’s USB outlet is also forbidden.
Similar restrictions on external chargers have been introduced by Thai Airways, Singapore Airlines, Air Asia, Taiwan’s major carriers, and Hong Kong Airlines.
The United States is not immune to the problem.
Back in December, the Federal Aviation Administration released data showing that “verified lithium battery-related events involving smoke, fire, [and] extreme heat” happened at least once a week on passenger planes in 2024.
FAA Rules for Flying with Lithium Batteries
Though lithium batteries have become ubiquitous in electronics because of their strength and compact size, they can overheat and ignite due to a process called “thermal runaway,” per the FAA. Contributing factors include damage, manufacturing defects, and improper storage.
Because “flight crews are trained to recognize and respond to lithium-ion battery fires in the cabin,” according to the government agency, spare lithium batteries, including power banks and phone chargers, must be stowed in carry-on bags on U.S. commercial flights rather than checked and placed in the cargo hold, where there’s no one around to put out the smoke.
FAA limits on which lithium batteries can be checked, which must be carried on, and which can’t come on the plane at all depend on the device’s watt hours (Wh).
Portable electronic devices like cell phones and laptops typically have batteries rated less than 100 Wh apiece, with cell phones coming in at 5 to 15 Wh and laptops in the neighborhood of 40 to 80 Wh. You weren’t planning on putting those devices in your checked bags anyway, were you? You’ll want to keep those items in your carry-on or personal item to prevent damage and to prevent not having access to your preferred tunes during the flight.
All spare batteries, power banks, e-cigarettes, and vapes must also remain in your carry-on, and the battery power of each device must be no greater than 100–160 Wh, per FAA regulations. You can’t have more than two spare lithium batteries in your carry-on, either.
The battery’s Watt hours should be marked somewhere on the item, according to the FAA, although you may need reading glasses and good light to read the print. If the product you have measures capacity using milliamperes per hour (mAh), make sure the limit is around 43,000 mAh, CNN advises.
Packing Tips for Flying with Lithium Batteries
If you are planning to travel with a power bank or other external charger, examine it first to see whether it is swollen or otherwise damaged, and do not fly with the item if you spot signs of wear and tear.
Protect the battery’s terminals from coming into contact with other metals—and thus potentially short-circuiting—by covering terminals with tape.
It’s also a good idea to pack power banks and other electronic devices in separate plastic bags or protective pouches to avoid coming into contact with each other.
Avoid charging power banks using the USB ports at your seat on the airplane (many Asian airlines won’t let you do that anymore even if you wanted to).
If you notice that any power bank or electronic device you have with you on a flight begins overheating, expanding, smoking, or burning, notify a flight attendant immediately.
And if you drop your cell phone or other device and can’t reach it, ask a flight attendant for help rather than grabbing madly and adjusting the seat. You could end up crushing the device, causing it to spark.
A dropped phone that can’t be located could result in the plane returning to where it started, but that’s better than a fire in the sky.
For more information on lithium batteries and airplane safety, see the FAA’s FAQ page on the subject.