British Airways passengers are facing the threat of an airline strike Jan. 10–11.

Roughly 15 percent of the airline’s cabin crew plan to strike for 48 hours starting today, a move which will likely disrupt travel plans for many airline customers.

The dispute involves members of mixed fleet cabin crew, those hired after 2010. Unite, Britain’s largest trade union, accused British Airlines of refusing to extend a previous mandate for industrial action. The airline instituted a two-tiered pay scale, with long-timers remaining well-compensated and new hires earning far less money.

“We have been informed by Unite that it has called strike action by mixed fleet cabin crew on January 10 and 11. We will plan to ensure that all our customers travel to their destinations. Mixed fleet Unite represents only 15 percent of our cabin crew. We are extremely disappointed that Unite has once again chosen to target our customer,” said British Airways. “We are now focused on protecting our customers from this unnecessary and completely unjustified action. Our proposal for our mixed fleet cabin crew reflects pay awards given by other companies in the UK and will ensure their reward levels remain in line with cabin crew at our airline competitors. It is also consistent with pay deals agreed with Unite for other British Airway colleagues.”

The cabin crew was due to walk out on Christmas Day and Boxing Day, but the action was suspended after talks at the conciliation service, Acas. Unite’s members rejected the offer by 7-1.

There are roughly 4,500 flight attendants out of 16,000 who work on mixed fleet contracts, but about 2,000 of them don’t belong to the union leaving only 2,500 to strike. The mixed fleet flight attendants work on both short- and long-haul flights but do not work on the same flights as pre-2010 hires.