A British Airways flight travelling from San Francisco to London had to be diverted to Vancouver after a medical emergency was declared on Tuesday morning.
Twenty five cabin and crew members were taken to hospital as a precaution but have now been discharged, an airline spokesman said.
There are conflicting reports over the exact nature of the medical reason for the diversion.
British Airways dismissed earlier reports that members of the cabin crew were treated for smoke inhalation, but did not elaborate on what their symptoms were.
The airline did not say what the cause of the problem was.
Photos of Flight BA 286 show the aircraft on the runway at Vancouver Airport.
The diverted flight landed on Monday at 11.30pm local time (7.30am on Tuesday BST).
Vancouver Airport tweeted to say that the aircraft had landed safely and medical assistance was provided.
British Airways apologised for the delay to their customers.
A British Airways spokesman said in a statement: “We are sorry for the delay to our customers’ flight but the safety and well being of our customers and crew is always our top priority.
“The flight from San Francisco diverted to Vancouver after members of the cabin crew became unwell.
“The cabin crew were checked as a precaution at local hospitals before being discharged.
“Our ground team at Vancouver has arranged hotel accommodation for the customers and will book them on alternative flights as soon as possible.
There has not been any confirmation how many people were on the Airbus A380 flight.