BERLIN (AP) — One-day strikes by unions representing pilots and cabin crew at Lufthansa caused a wave of flight cancelations Thursday at Germany’s biggest airline.

Lufthansa criticized the walkouts as disproportionate but said it expects to offer a largely normal flight program Friday.

Lufthansa said the strikes called by the Vereinigung Cockpit and UFO unions led to extensive cancelations, but didn’t give a specific figure. The departures board at the airline’s main Frankfurt hub suggested most of its flights from there Thursday morning were canceled.

The airline said it was trying to rebook passengers onto flights by partner airlines and other companies from the Lufthansa group, which includes airlines such as Swiss, Austrian Airlines and Brussels Airlines.

The two unions called for the 24-hour walkouts on Tuesday.

Vereinigung Cockpit called for walkouts on flights departing from Germany in a dispute over the pension system for pilots at the airline and its Lufthansa Cargo unit.

UFO called for members to strike on flights departing Frankfurt and Munich and flights by the Lufthansa Cityline unit in a dispute over its demand for negotiations on various issues.