Many Hawaii-bound travelers now board with at least one power bank in their carry-on. We plug in our personal devices and then settle into a flight where the nearest runway may still be up to three hours away if something starts smoking in the cabin.

That risk is no longer theoretical. A passenger’s portable charger reportedly caught fire this week on a United flight between Zurich and Newark. The crew turned toward London, and the aircraft was on the ground at Heathrow about 35 minutes later. On a Hawaii flight, that clock runs very differently.

Hawaii flights are safe. The harder question is what happens when a cabin emergency involves the one item nearly everyone now brings onboard, and the nearest runway is hours away instead of minutes.

The flight diversion ended quickly.

According to The Aviation Herald, the aircraft was a United Boeing 767, and the passenger whose power back caught fire was seated in premium economy. Emergency vehicles at Heathrow met the aircraft after landing.

The aircraft was operating over Europe, surrounded by airports and densely packed airspace, with a runway available once the crew turned toward London. The Pacific almost uniquely changes that equation because even a safe, controlled diversion can still leave passengers and crew airborne for hours before reaching a runway.

Hawaii flights operate under a very different reality.

Hawaii routes operate under strict long-range overwater requirements, and airlines always remain within approved diversion ranges throughout flights. Pilots continuously monitor alternate airports, fuel burn, weather systems, and aircraft performance when crossing the Pacific to and from Hawaii, and modern aircraft are designed specifically around this type of flying.

A Hawaii flight halfway between California and Honolulu, or a redeye returning overnight to the mainland, can remain hours from landing after a diversion is called for. Anyone who flies to and from Hawaii likely has given this some thought.

After two hours in flight, we are already wondering whether we are closer to the mainland or to the islands. That is because when anything goes wrong, the airplane will be heading in one direction or the other.

By the third hour of an overnight to the mainland, most of the cabin is asleep, often with phones and tablets plugged into power banks around them. Bags are packed under seats. The map screen still shows water in every direction. That is the part of the flight where a smoke event becomes a multi-hour event, not a 35-minute one.

Why airlines worry so much about power banks now.

Lithium battery fires pose a different challenge from ordinary cabin fires because the battery itself can continue generating heat even after visible flames appear to be extinguished. This thermal runaway is a chain reaction inside the battery cell that can keep reigniting unless the device is cooled and isolated.

Hawaii routes have already seen their own reminders about just how this works. In 2024, Hawaiian Airlines Flight 26 between Honolulu and Portland experienced an onboard iPad fire, and the response in the air raised hard questions about how prepared crews actually are when a battery goes into thermal runaway in a packed cabin.

Flight attendants are trained not simply to put out the initial flare-up, but to continue monitoring and cooling the device for the remainder of the flight. Many airlines now carry thermal containment bags designed specifically for overheating electronics, and crews may spend significant time managing a single damaged battery after the initial emergency appears over.

The industry has also seen these incidents emerge through increasingly ordinary situations. That includes devices that slip into reclining seat mechanisms and become crushed during flight. Chargers overheat during continuous use. Damaged batteries continue being used after swelling or impact damage.

Airlines understand that the overwhelming majority of lithium batteries pose no problems. The concern is scale. Nearly every passenger now travels with multiple high-capacity batteries, and Hawaii flights combine long durations, overwater flying, overnight operations, and cabins filled with continuously charging electronics.

Three hours can feel very different than 35 minutes.

A smoke event onboard a European flight may mean the airplane is parked at the gate before passengers fully process what happened. On a Hawaii route, the same event can unfold under very different conditions, even when the crew responds perfectly, and the aircraft remains fully under control.

Picture a darkened overnight flight between Honolulu and the mainland, with the seatbelt sign illuminated above sleeping passengers. A faint smoke smell drifts into part of the cabin, nearby travelers begin looking around to understand where it is coming from, and flight attendants move quickly through the aisle carrying gloves, water bottles, and containment equipment.

Someone several rows away is told to unplug a device, while another passenger suddenly realizes the smell may be coming from a backpack pushed beneath a nearby seat. Outside the window, there are no visible city lights, highways, or coastline below, only darkness and open ocean stretching across the moving map screen.

Modern crews train extensively for exactly these situations, and commercial aviation remains remarkably safe. What changes is the sense of time, because passengers understand the airplane may still remain airborne for hours after the diversion decision happens.

The crew may be doing everything right and the battery may already be contained, yet the flight can still have hours left before anyone steps onto a runway.

Airlines are tightening the rules.

Airlines are becoming more aggressive about portable charger policies, especially on longer and overwater routes. Southwest already requires power banks to remain visible while in use, with no charging inside bags or overhead bins, and other carriers are thought to be moving quickly in the same direction.

As we covered previously in New Inflight Portable Charger Ban Reaches Hawaii Route December 15, airlines increasingly view portable power banks as one of the highest-risk personal items regularly brought onboard. Long, overwater flying is where much of that enforcement is appearing first, and travelers should expect more restrictions ahead, not fewer.

What this means for the next time you fly to Hawaii.

For most Hawaii travelers, the practical takeaway is simple. Carry fewer spare batteries and keep portable power banks where you can see them, rather than buried inside luggage. Editor Jeff likes to keep his visible in his seat pocket.

Recently, more announcements include something to the effect that if a device becomes unusually hot, starts swelling, smells odd, or slips into a seat mechanism, to tell a flight attendant immediately rather than trying to handle it privately. Cabin crews would far rather respond early to a small problem than discover it later after smoke appears in the cabin.

The crew wants exactly what passengers want on a Hawaii flight: a long, uneventful crossing where nothing memorable happens. Portable chargers offer a new type of concern that is just now being addressed.

Have you ever known of issues with portable chargers on a flight?