BERLIN: Deutsche Lufthansa said it was canceling more than 1,000 flights ahead of a one-day walkout by ground staff scheduled for Wednesday, just as families across Germany head off on their summer holidays.Strikes and staff shortages have already forced airlines including Lufthansa to cancel thousands of flights and caused hours-long queues at major airports, frustrating holidaymakers keen to travel after COVID-19 related lockdowns.Germany’s flagship carrier has canceled 678 flights at its Frankfurt hub, most of which were scheduled for Wednesday, and 345 flights at Munich, Lufthansa said on Tuesday.More than 130,000 passengers are affected, Lufthansa said, adding that there could be a few more cancelations and delays on Thursday and Friday, after the end of the strike called by labor union Verdi in pursuit of a 9.5 percent pay claim.