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To contradict the above post, I have a good friend and FTer who recently applied to be an FA with a US-based carrier. They did the drug test and background check and then eventually disqualified him for being too tall, something they knew about from the very beginning of the process. So companies will run those processes in parallel in many cases and only reconcile all the data at the end. I wouldn't consider it a sure thing until the call comes in.