Vision doesn't miss when he attacks Sam during the escape from the airport. (Since Sam is flying behind both Rhodey and Tony and considering that in the movie neither Sam nor Tony catch up to Rhodey in time, it's doubtful that either of them would've managed to catch Sam.)

So Sam hits the ground, only he's wearing less armor than Rhodey, so how much worse are his injuries? Does he die? Does Steve turn the Quinjet around when he realizes what's happening or does he keep going?