German flag-carrier Lufthansa has cancelled around 900 flights at the start of a three-day strike by pilots begins.
Pilots walked out at midnight, April 2nd and are not expected to return to work until 23:59 on Friday.
Some 425,000 passengers are likely to be affected today.
Lufthansa said a further 3,000 flights will be grounded over the next three days, making it one of the biggest stoppages in the airline’s history.
Pilots are demanding a new pay and pensions deal from the airline.
The airline’s budget arm, Germanwings, and freight carrier, Lufthansa Cargo, have also been affected by the strike.
Lufthansa said all passengers affected by the strikes can rebook or cancel their flights free-of-charge.
Other subsidiaries, including Austrian Airlines and Lufthansa Cityline, are not affected.
Messages have been sent out to as many passengers as possible, while sleeping arrangements and food have been prepared at airports for those who did not receive warning.
The action is likely to cost the airline millions of euros.