Passengers on a fog-hit British Airways flight to Calcutta suffered a double whammy when low visibility at the airport forced the plane to be diverted to Hyderabad and a mandatory rest period for crew ensured that it remained there.

The flight was to arrive in Calcutta at 2am on Friday but Air Traffic Control refused permission to land because of fog over the runway. The diverted plane could have returned to Calcutta when visibility improved in the morning but it was time for the crew to rest by the time the green signal came.

The 271 stranded passengers were provided lodging in Hyderabad and flown back to Calcutta on various domestic flights.

“All members of the crew need to rest for a specified period after a flight, which is why our plane could not be flown back to Calcutta on Friday,” a British Airways spokesperson said.

The flight will finally arrive at 11am on Saturday and take off on its return journey at 1pm. The 146 passengers booked on the return flight suffered just as much as those on the plane. Some were checking in when the airline announced that the flight had been diverted to Hyderabad.

Kulendu Bole, a Philadelphia-based businessman who was to return to the US via Heathrow, said he was worried about not getting a connecting flight after missing the one in which he and his family were booked. “We reached the airport around 3am and were in the queue at the check-in counter when it was announced that the flight had been cancelled,” said Bole.

The passengers were later told that the flight hadn’t been cancelled. “We were informed that it would take off at 1pm on Saturday. But by the time we reach London, there will be no connecting flight to the US. The airline has promised us lodging but the delay will be a bother,” said Bole.

Airport officials confirmed that the “flight duty time limitations” of the cabin crew and the pilots of the British Airways aircraft had run out.

Time limitations are calculated on the basis of several factors, including flying hours, the number of pilots on board, landings and duty shifts.

On Wednesday, Pakistani passengers on board a Dhaka-Karachi flight diverted to Calcutta because of fog were not allowed to disembark because the rules stipulate that air travellers from that country must clear immigration either in Delhi or Mumbai.