If you’re planning to fly somewhere this weekend on U-S Airways you’d better phone ahead. The carrier’s flight attendants threaten to strike when their contract expires at midnight tonight. One travel agent says it could end up causing a lot of delays or leave some travelers stranded.Terry Beech, the executive vice president of Continental Travel in Des Moines, says some of U-S Air’s commuter services will be flying in Iowa, but other commuters may cease operations with the strike.Beech says reports are conflicting, but it appears Air Midwest and U-S Air Express WILL continue to fly during the strike, but U-S Air METRO Express may NOT be flying. She strongly urges ticketholders to call ahead and double-check the status of their flights.