LONDON — The cabin of a British Airways flight filled with what appeared to be white smoke as it prepared for landing in Spain on Monday afternoon, prompting the airline to evacuate more than 170 passengers, with three taken to the hospital.

In an emailed statement on Tuesday, the airline acknowledged that its flight BA422 from Heathrow Airport near London had experienced a technical issue on its landing approach into Valencia, Spain’s third-largest city.

The statement added that three passengers had been taken to a hospital as a precaution and had since been discharged, and that the airline was investigating the details of what had happened.

That came as little comfort to many of those onboard the flight, some of whom posted on social media about their experience.