Labor turmoil in the airline industry has travel experts warning consumers to carefully plan trips this summer. The four largest US carriers are ALL working to resolve open contracts with unions. Thousands of airline workers are under court order NOT to disrupt flight schedules. Although unions at Northwest and Delta are moving toward settlements, workers at the nation's two largest carriers are threatening to strike. Minnesota Public Radio's Mark Zdechlik tracked down some advice on ways YOU can steer clear of airline problems if you're planning a trip.