First you see a woman's head down in his lap area kind of, but then you realize it is an older stewardess wiping up something from his lap and saying something like I don't think it will be a serious burn. Then the young stewardess apologizes re the wife, but it seems she is talking about his shirt (which the wife would have to clean of course!), and the overall impression is she spilled hot coffee on his shirt.
Re accuracy, I don't think there were many whitehaired stewardesses at that point... they had to sue to be allowed to work past about 30 as I recall, and even if that had happened (by 1976) none of them would have had white hair yet. But maybe she was just a super bleached blonde.