British Airways (BA) has cancelled nearly all 1,700 flights as pilots hold a 48-hour strike to dispute pay.
British Airline Pilots’ Association (BALPA), which represents the pilots, said that the first day of the strike will cost BA approximately £40m.
The strike is expected to affect around 150,000 to 200,000 passengers.
Before it began on Monday 9 September, the airline cancelled more than 50 intercontinental flights to Heathrow Airport in the evening on Sunday 8 September.
Most cancelled flights were headed to North American destinations such as New York, Boston, San Francisco, Chicago, Los Angeles and Toronto.
Flights services from Chennai, Lagos and Mexico City to Heathrow were also cancelled.
The strike is said to be the biggest in BA’s history and has stopped flight services at Gatwick Airport.
BALPA general secretary Brian Strutton said: “British Airways needs to wake up and realise its pilots are determined to be heard.
“They’ve previously taken big pay cuts to help the company through hard times. Now BA is making billions of pounds of profit, its pilots have made a fair, reasonable and affordable claim for pay and benefits.
“The company’s leaders, who themselves are paid huge salaries and have generous benefits packages, won’t listen, are refusing to negotiate and are putting profits before the needs of passengers and staff. It is time to get back to the negotiating table and put together a serious offer that will end this dispute.”
BA has offered an 11.5% pay increase over three years, which the airline claims will increase the annual salary of some captains to higher than £200,000.
The airline has asked passengers to apply for refunds or book another flight with BA or an alternative airline.
The UK Civil Aviation Authority said that British Airways should send passengers to their destinations at its own expense, even if this involves arranging flights with a different airline.