The biggest strike action in BA’s history is now underway with the airline cancelling almost all of its flights today and tomorrow.

BA blamed the British Airline Pilots’ Association (BALPA)  for a lack of detail about which pilots would strike. It said without this information the airline had no way of predicting how many pilots would come to work or which aircraft they would be qualified to fly. As a result nearly 1,600 flights are cancelled over a two-day period.

Customers booked to travel on cancelled flights have the option of a full refund or re-booking to a different date of travel or alternative airline. BA advised customers to check the “Manage My Booking” section of BA.com to find out about their refund and rebooking options. Those passengers who booked with a travel agent were told to contact their agent directly.

A further strike day is scheduled for 27 September. Passengers travelling on or around this date will be contacted by BA in the next few weeks if their flight is impacted.

BALPA said the strike action sends a clear message to BA’s managers that pilots will not be fobbed off in their dispute over pay and benefits.

Pilots have walked out after earlier negotiations broke down. BALPA said BA has subsequently refused to consider alternative proposals or get back together for further constructive talks. However, BA said it remained ready and willing to return to talks with BALPA.

BALPA accused BA of breaking agreements and “threatening” pilots who will strike, describing the airline’s behaviour is “illogical and irresponsible”. Various reports claim the airline emailed pilots warning them that they would lose generous travel perks for themselves and their families for the next three years if they took park in the walkout.

A statement from BALPA said: “British Airways would clearly rather inflict this bullying tactic on its staff and see its passengers take the brunt of the strike action inconvenience than engage with its employees to find a way forward.

“Pilots, who took pay cuts in the years following the financial crisis to help shore up the company, say BA’s fat cat managers have failed time and again to listen to their staff and seem determined to force pilots to take the strike action.”

BALPA said BA makes about £2bn profit a year and the cost of BALPA’s latest proposal is less than £5m more than the airline previously offered. It calculated that one day of strike action costs the company about £40m.

Brian Strutton, BALPA general secretary, 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.

“BALPA has consistently offered up chances for the company to negotiate a way forward. British Airways must now put the needs of its staff and passengers first and accept that its pilots will not be bullied or fobbed off.

“But 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. This strike will have cost the company considerably more than the investment needed to settle this dispute.

“It is time to get back to the negotiating table and put together a serious offer that will end this dispute.”