Finnair will cancel nearly its entire schedule on Feb. 1 and 2 due to strikes involving several government employee unions that will impact Helsinki Airport.
In total, Finnair will cancel 550 flights over those two days out of the approximately 560 it would typically operate.
On Jan. 19, anticipating the strike, Finnair began offering customers with bookings on Feb. 1 or Feb. 2 the opportunity to rebook through March 15.
On Monday, the carrier began implementing the cancellations in its system and offering alternative routing to flyers who hadn't already made changes.
"We will do our very best to offer a suitable flight option to as many customers as possible, but the number of alternative flights is limited," said vice president of operations Jari Paajanen in a prepared statement. "We ask customers to kindly wait for the rerouting from us, as our customer service team is busier than usual and queue times can be long."
Flyers from the U.S. who had planned to connect through Helsinki will instead be routed to directly to their destination on another airline.
From the U.S., Finnair had flights to Helsinki scheduled from New York, Miami, Dallas and Los Angeles on either Thursday or Friday.
Finnair is a Oneworld alliance member.