Welcome aboard the xyz train.
Welcome aboard on the xyz train.
Are both the above sentences grammatically correct?
I don't really know how to use the "Welcome aboard" part right, greeting someone for their coming on board on whatever train/plane I'm on.
Like when they make inflight announcements saying "Welcome aboard xyz airlines". Is it okay to use the preposition on following the aboard in constructions like these?
We never use on or any other preposition with "Welcome aboard". This is because you are aboard the vessel, not "aboard on" the vessel. "Aboard" basically already means "on", so there's no reason for any other preposition.
Is it possible you're confusing "aboard" with "on board", which is another phrase that means pretty much the same thing? You wouldn't use another preposition after "on board" either, though.
