They took a flight to London, but instead landed in a city hotel.

A British Airways flight carrying 253 passengers and 13 crewmembers made an emergency landing at the city airport an hour after taking off, after a fire alarm went off in the cockpit.

About 20 minutes after the flight took off for Heathrow — it’s departure time was 3 am on Thursday — a fire alarm started ringing in the cockpit.

The pilot turned the plane back for the Mumbai airport where fire tenders, ambulances and a fleet of safety vehicles prepared for an emergency evacuation were waiting on the tarmac. However, no fire was detected in the aircraft.

“There was a technical fault with the fire alarm system,” said an airline spokesperson.

After the emergency landing at 4.06 am, the pilot asked an airport safety vehicle to check the aircraft externally.

“The safety jeep checked the bottom of the aircraft and no damage was reported,” said the Mumbai International Airport Limited spokesperson.

The plane advanced to the parking bay and passengers were evacuated. The pilot also dumped a major part of the fuel in the sea as a precautionary measure before making the emergency landing.

“It is procedure to dump fuel in case of such emergencies,” said an airport staff, requesting anonymity, as he is not authorised to talk to the media.

The airline put up the passengers in a hotel at 6 am.

The passengers are likely to travel in the same aircraft scheduled to leave Mumbai on Friday morning.

The airline claimed that some passengers were put in an afternoon flight to London on Thursday but did not give out details on how many were left in the hotel.

This is not the first time that a false fire alarm had disrupted a flight. On June 12, a Frankfurt-bound Air India flight carrying 264 passengers aborted the journey after the fire warning lights went on.

On inspection, the staff found that the safety device picked up pungent stench from a packet of pickle wrapped in a passenger’s baggage.