Some recent iPhone owners are reporting a strange and worrying issue. Their phones appear to swell mid-flight, then return to normal once the plane lands. While the number of cases remains small, the pattern has raised questions about battery safety during air travel.
The reports focus on newer iPhone models, including the iPhone 16 Pro Max and iPhone 15. In these cases, users noticed the back panel lifting away from the frame while the plane was in the air. The phones did not overheat, shut down permanently, or catch fire. Still, visible swelling during a flight is not something to ignore.
Reddit users shared the first detailed accounts of the issue. One post on r/iphone described an iPhone 16 Pro Max that began swelling during a flight and separated enough for the user to see a visible gap. After landing, the phone “was back to normal.” Another user reported the same behavior with an iPhone 15 across two separate flights. In that case, the problem stopped only after Apple replaced the battery.
Battery may swell in the air
Several commenters offered a possible explanation that fits the pattern. Lithium batteries can produce gas over time. At normal ground pressure, that gas stays compressed. Inside an aircraft cabin, air pressure drops compared to sea level. That pressure change may allow trapped gas to expand, causing the battery to swell temporarily.
This theory explains why the swelling appeared during flight and disappeared after landing. It also explains why replacing the battery solved the issue for at least one user. Not all batteries behave the same way. Manufacturing variations can leave some units more vulnerable than others.
Older aircraft or cabins with higher pressure altitudes may increase the effect. Even modern planes do not maintain sea-level pressure. Most cabins simulate an altitude of several thousand feet, which is enough to stress a defective battery.
Why is this still a serious risk
Even if the swelling goes away, the danger does not. Battery expansion can damage internal seals. Once that happens, the phone’s water and dust resistance is no longer reliable. More importantly, a compromised battery raises the risk of thermal runaway, especially during charging.
One commenter summed it up clearly, calling battery swelling “a mandatory battery replacement” because continued use risks “thermal runaway fire.” That risk matters more on a plane, where a battery fire becomes a serious safety threat.
What you should do if this happens
If your phone swells during a flight, alert the crew immediately. Do not try to ignore it or power through the flight. Airline crews train for battery incidents and can respond quickly.
Take photos if it is safe to do so. Several users reported that Apple initially dismissed their complaints, stating that batteries “don’t just un-swell.” Photos taken during the flight helped prove the issue and secure a replacement later.
After landing, stop using the device and book a service appointment. Even if the phone looks normal again, the internal damage may already exist.
A rare issue, but not one to dismiss
This problem appears rare, but the consequences are serious. One faulty battery can turn a routine flight into a dangerous situation. If more reports surface, Apple may need to look closely at battery quality in recent models. Until then, any sign of swelling deserves immediate attention.
Had that happen to a MBP but it wasn’t the elevation, it was the extreme cold temps that I had to endure, frequently. Fina;lly had to get rid of it because I thought it might start a fire if the battery expaned anymore. It swelled so mush that it destroyed the Bletooth module in it.