“Terrified” passengers had to evacuate a British Airways flight using the emergency slides after the cabin filled with smoke as it prepared to land in Valencia.
Passengers heading to the Spanish city from London Heathrow tweeted about their “shock” at the incident.
Gayle Fitzpatrick said it happened minutes before the aircraft was due to land.
Mrs Fitzpatrick, from Glasgow, said: “It was very scary. The flight was just ending, and with 10 minutes to go, it started descending rapidly as smoke started to fill the cabin.”
She said there was talk an “air conditioning unit” may have been to blame and claimed there were “no communications from the crew”.
Some of the crew started to wear oxygen masks and protective fire gear, said Mrs Fitzpatrick.
“We were not told it was an emergency until we had landed and they were trying to open the cabin doors for passengers to jump down the chutes,” she said.
“There were fire engines waiting and then we were all ushered into a bus then to the airport.
“We are still waiting to hear what happened. People were crying and hyperventilating. It was genuinely scary.”
Lucy Brown tweeted that it was a “terrifying experience”, which felt like a “horror film”.
Another passenger, Stephen McConnon, said BA’s handling of the situation was “shocking” and claimed there was “no oxygen, no announcements”.
He tweeted: “It was the most terrifying experience of my life and no reaction from you. Shocking!!”
Photos and video on social media show people leaving the aircraft on the emergency slides.
The airline said in a statement: “We can confirm that British Airways flight BA422 from Heathrow to Valencia has been involved in an incident today.
“The aircraft, an A321, has landed and all customers and crew have disembarked.
“British Airways teams are assisting customers who are in the airport terminal.”