A British Airways Airbus A380 performs during the 50th International Paris Air Show at the Le Bourget airport in Paris, France, June 17, 2013. The Paris Air Show runs from June 17 to 23. (Xinhua/Gao Jing)

British Airways faced its first global strike by pilots on Monday and the possibility of almost all its flights being grounded for two days.

The UK flag carrier and its 4,300 pilots have been locked in a nine-month pay dispute that could disrupt or alter the travel plans of nearly 300,000 people.

The British Airline Pilots Association (BALPA) has rejected a pay increase of 11.5 percent over three years that the airline proposed in July.

BA says the offer would see flight captains receive "world-class" pay and benefits of around £200,000 ($246,000) a year.

BALPA counters that co-pilots' salaries average around £70,000.

This leaves some in heavy debt since they must first undergo training that the BBC estimates costs around £100,000.

The union said that BA never replied to a counteroffer it made on Wednesday.

Pilots are threatening to strike for one more day on September 27 should the dispute rage on.

AFP