I don't care that John McClane is a cop, he traveled to another city (whether the start has him returning to his home state or visiting from it), and I don't care how things were in the late 80s, but a cop shouldn't carry his gun so close to his chest in a plane between jurisdictions where he goes out of his line of authority. Nobody should carry a gun in a commercial plane, don't these things have sensitive triggers?
Bruce Willis working in a security and coming to his wife and their troubled marriage from a different state? I wonder if Unbreakable took cue from this movie for this bit early in the story.