Several passengers were hospitalised after a plane was forced to make an emergency diversion due to smoke in the cabin.
Delta flight DL251 had left Barcelona for Boston Logan International Airport when the smoke was spotted on board.
The Airbus A330, carrying 296 passengers, was diverted to Porto in northern Portugal, where it made an emergency landing.
Flight data showed the flight had left the Catalan capital at 3.15pm on Sunday.
But a mechanical issue was reported about two and a half hours after takeoff.
A total of 14 passengers reportedly inhaled smoke, with eight treated on the ground at Francisco Sá Carneiro Airport in Porto.
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Three more passengers were taken to hospital, a spokesperson for Portugal’s emergency and civil protection authority said.
The incident remains under investigation.
A spokesperson for Delta said: ‘“Delta flight 251 from Barcelona to Boston diverted to Porto, Portugal following a reported mechanical issue.
‘The flight landed safely, and we apologize to our customers for the delay in their travels as we work to get them to Boston as safely and quickly as possible.’
It’s not the only time similar incidents have been recorded on planes.
Last month around five passengers suffered burns on an American Airlines flight from Atlanta to Dallas after laptop battery fire in the cabin.
A KLM Boeing 777 was forced to turn around over the Atlantic Ocean after a charging power bank ignited at a business class seat.
The passenger, who was a former airline boss, had fallen asleep after breaking airline protocols forbidding any charging of power banks on board.
Last year, the International Air Transport Association (IATA) launched a campaign to improve awareness of the danger of lithium-ion batteries onboard aircraft.
An average of 2.36 incidents relating to lithium-ion batteries happened on planes every week in 2025, a study by UL Standards and Engagement found.
Some 12% of incidents led to a flight either diverting or performing an emergency landing, costing airlines millions of pounds, the organisation said.
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