Northwest Airlines is offering flight attendants two free first-class tickets anywhere in the world for reporting as scheduled for holiday duty. It's an attempt to cut down on sick calls over the holidays. In a recent letter to workers, Northwest in-flight services chief Lloyd Warren thanked flight attendants in advance for reporting for holiday duty. And as ``a token of our thanks,'' Warren said, two free round-trip tickets in first-class seating would be given to flight attendants who report as scheduled between Dec. 15 and Jan. 1. Northwest employs more than 8,000 flight attendants. To qualify, workers must be scheduled for flights on Dec. 24, Dec. 25, Dec. 31 or Jan. 1. Service charges that normally accompany worker flight-pass privileges would be waived. Northwest spokesman Doug Miller said that last year, flight attendants were offered a $100 cash bonus for working through the holidays. Miller said the offer does not reflect a problem with holiday sick leave in the ranks of flight attendants. ``It's just that when we're in crunch time like we are around the holidays, every single person is key to our success,'' he said.