So I'm the airline and it's reported to me that he smells of alcohol.
I'd call him in. I wouldn't breathalyse him 'cos then it's irrevocable.
I'd say, "Go home. If you are having alcohol or domestic or stress problems I want to know about it RIGHT NOW so we can get you help, because the next time there's even a hint of a mint you're going out the door so fast your feet won't even touch the ground."
I've done it to a colleague who is now 6 years clean (and happy and OK).
Just my 2d.
Mac