A United Airlines Boeing 767-300 bound for Newark made an unscheduled landing at London Heathrow on May 5. A passenger’s portable power bank triggered a lithium battery cabin fire in premium economy. The incident occurred at flight level 340 — roughly 34,000 feet over the English Channel.
The aircraft, flight UA-135 (registration N675UA), was operating from Zurich. It was approximately 110 nautical miles southeast of Heathrow when the crew declared a diversion. The 767 landed safely on runway 09L about 35 minutes later. Emergency services met the aircraft on the apron; no injuries were reported. United cancelled the remainder of the flight to Newark, according to The Aviation Herald.
A Regulatory Framework Under Strain
Power banks are already among the most tightly regulated items a passenger can carry. FAA and EASA rules, harmonized through ICAO, permit portable batteries up to 100 watt-hours (Wh) in carry-on bags. No approval is needed. Devices rated 100–160 Wh require airline sign-off; passengers may carry no more than two. Anything above 160 Wh is banned from passenger aircraft cabins.
In March 2026, ICAO tightened the rules further. Passengers are now capped at two power banks and prohibited from in-flight recharging. Furthermore, more than 20 airlines — including Lufthansa, Emirates, and Qantas — now ban in-flight power bank use entirely.
Moreover, the rules exist because the physics are unforgiving. Lithium-ion thermal runaway produces flames up to 1,107°C (2,025°F). That is hot enough to instantly ignite cabin materials. Critically, FAA SAFO 25002 warns that Halon extinguishers suppress visible flames but do not stop thermal runaway. Only sustained water cooling — flooding the device — will arrest the chain reaction.
Lithium Battery Cabin Fire Incidents Are Rising
The UA-135 diversion is not an anomaly. The FAA recorded 89 verified onboard incidents involving lithium batteries in 2024, a 16 percent increase over 2023. Power banks were the leading cause, accounting for 27 of those events — roughly one every two weeks. In 2025, power banks retained the top spot with 26 incidents reported through mid-year, ahead of e-cigarettes and cell phones.
Additionally, approximately 18 percent of onboard lithium battery incidents led to a diversion, emergency return, or unplanned deplaning. On long-haul oceanic routes — where UA-135 was flying — the options narrow considerably. The crew’s 35-minute window to Heathrow was on the favorable end of what transatlantic geometry allows.
The trajectory has airlines treating consumer rechargeable batteries as an operational risk category in their own right, rather than an edge case. Carry-on policies, crew training, watt-hour signage at the gate, and in-flight charging bans have all tightened in the past 24 months. The expectation among safety regulators is that the rules will continue to tighten as device density per passenger climbs.
What Investigators Will Want to Know
The UK Civil Aviation Authority (CAA) will likely examine three questions. Did the power bank comply with the applicable watt-hour limit? Did it carry a legible label? Did the crew’s firefighting response follow SAFO 25002 guidance? Passenger accounts cited by The Aviation Herald describe a “small fire” in premium economy — consistent with early-stage thermal runaway before full cell venting.
The aircraft, registration N675UA, is a Boeing 767-300ER on United’s transatlantic routes. No structural damage has been reported. The incident comes as investigators continue reviewing a broader pattern of cabin-smoke events.
FODNews will update this report as the CAA investigation progresses.
Sources
- The Aviation Herald — Incident: United B763 near London on May 5th 2026, PED caught fire
- FAA SAFO 25002 — Managing the Risks of Lithium Batteries Carried by Passengers and Crewmembers (August 2025)
- FAA PackSafe — Lithium Batteries
- ICAO — New power bank restrictions will safeguard international aviation (March 2026)
