THOUSANDS of travellers are to be hit on a second day of strikes by British Airways pilots which will ground some 64 flights in Scotland today.

Heathrow Terminal 5, BA’s main operating hub, was almost deserted for the first day of the strike, when it would normally be bustling with passengers.

BA carries about 145,000 passengers on an average day.

And the same is expected today on the second day of the strike called by the British Airline Pilots Association (BALPA) in a long-running pay dispute.

Today at Edinburgh Airport there were 20 flights that were cancelled to or from Heathrow and Gatwick.

READ MORE: Up to 190,000 UK passengers hit as strike wipes out BA flights

A further 28 flights between London Heathrow and Gatwick and Glasgow were cancelled.

HeraldScotland: A damaged British Airways at City Airport in London after it made a crash landing

At Aberdeen Airport there were six Heathrow flights grounded and at Inverness a further two were expected to be cancelled.

It is the first time BA pilots have gone on strike in an action that could cost the airline up to £40m a day.

The walkout is due to come to an end at midnight on Tuesday, although there could be additional unexpected cancellations on Wednesday.

READ MORE: BA pilots set to strike in dispute over pay

BA passengers have been advised to avoid airports during the two-day action, which started at midnight.

BALPA said that strike action was supported on Monday by virtually 100% of members.

The union said management's cost-cuts and "dumbing down" of the brand had eroded confidence in the airline.

Both sides have said they would hold further discussions, but no date has been set and another strike is scheduled for September 27.

Balpa general secretary, Brian Strutton, said: "It is time to get back to the negotiating table and put together a serious offer that will end this dispute."

BA said: "We understand the frustration and disruption Balpa's strike action has caused our customers. After many months of trying to resolve the pay dispute, we are extremely sorry that it has come to this.

"Unfortunately, with no detail from Balpa on which pilots would strike, we had no way of predicting how many would come to work or which aircraft they are qualified to fly, so we had no option but to cancel nearly 100% of our flights."

BA chief executive Alex Cruz apologised to passengers for the disruption and insisted the airline had worked tirelessly to contact everyone affected by the strike to offer alternative arrangements.

He said: "I'm really sorry for the position the cynical actions of the pilots' union has put us in. It's by all accounts an own goal for the union.

"It's going to punish customers, it's going to punish our brand, it's going to punish the rest of our colleagues - over 90% (of BA employees) have already accepted the 11.5% deal."

BA has offered a pay rise of 11.5% over three years, which it says would boost the pay of some captains to £200,000, but Balpa says its members want a bigger share of the company's profits.

BA has spent weeks offering refunds to passengers or the option to rebook on another date of travel or an alternative airline.

The airline said that since Balpa issued the strike dates it has tripled the number of staff supporting customer contact teams.