warning: turbulence could soon hit flights as pilot unions resist vaccine mandates and risk losing their jobs. what we re looking for is to c.ure that there s a i rorte representing american airlines 15,000 pilots warnedff shtages could start as soon as holiday travel begins. if you suddenly in one day have 4,000-plus pilots that are not able to fly, that s a big deal. that s worse than this past summer. reporter: but the largest pilots association and most major carriers confirm they will follow president biden s executive order requiring airline workers to get the shots. united says hundreds of its own vaccine holdouts changed course in just the last week. one airline, however, is flying a different route. some have very deep-seated feelings and concerns about the vaccine. i want to respect that. reporter: dealt boston ed bastian says he is undecided on the mandate and points to a