"aboard" means " on board"

Q:
posted by MAS1981 on 11/5 9:52 AM
Welcome ____ the flight to Taipei. (Why can't I use on or board?) Thank you very much. (Ans: aboard)

A:
posted by clif on 11/5 11:22 AM
The traditional way of welcoming people onto a flight is: "Welcome aboard the flight to Taipei." You can also say "Welcome on board the flight to Taipei." "Aboard" and "on board" mean the same thing. There is technically nothing wrong with "Welcome on the flight to Taipei.", but that's just not the traditional way of greeting passengers. "Welcome, board (that is: get on) the flight to Taipei." is grammatically correct, but it is a very abrupt and rude way to greet passengers.

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Q:
posted by MAS1981 on 11/6 5:00 AM
How come "Welcome board the fight to Taipei." is abrupt and rude to greet passengers???

A:
posted by clif on 11/6 11:16 AM
In the sentence "Welcome board the flight to Taipei." it depends on how you interpret the words in the sentence. If you interpret the word "board" as a verb, then you're using the verb as a command: "Board the flight to Taipei!" Only on a military flight where the passengers are enlisted men and the greeter is an officer would the passengers be welcomed this way. On a commercial airline flight the passengers would never be commanded to get on the plane like this.

The sentence might be permissible if you interpret
the word "board" as an abreviated form of
"aboard" or "on board"--you're omitting the "a" or
the "on," as in: "Welcome 'board the flight to
Taipei." If you're an experienced flight attendent
and you've said this a million times, you might after
a while get lazy about it an slur your words, omitting
the "a" or "on," and if you do it smoothly with
the right inflection in your voice, this might be
okay in some circumstances. But it would be
better to say the words properly all the time:
"aboard" or "on board."
轉貼自http://mb.sparknotes.com/mb.epl?b=2437&m=1289827&f=1&t=363788#1289827