Looking on the internet deeply has found these results:

Welcom aboard is the most popular phrase on the web.

welcome on board 12,900,000 results on the web	Welcom aboard 18,840,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Ladies and gentlemen and variations thereupon, welcome on board the Crusader 50. This is your captain Welcome on board Instant Hell Airline Ladies and gentlemen and variations thereupon, welcome on board the Crusader 50, if you would fasten your seatbelts, we'll be leaving any moment. Cmdr Data, welcome on board. Ladies and gentleman, welcome on board this Great British Air flight 287 to Barcelona. Welcome on board, Mr. Dallas. Dr Jackson, welcome on board the Prometheus. Welcome on board, Mr. Thevenet.	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

welcome on board

12,900,000 results on the web

Welcom aboard

18,840,000 results on the web

More popular!

Ladies and gentlemen and variations thereupon, welcome on board the Crusader 50.
This is your captain Welcome on board Instant Hell Airline
Ladies and gentlemen and variations thereupon, welcome on board the Crusader 50, if you would fasten your seatbelts, we'll be leaving any moment.
Cmdr Data, welcome on board.
Ladies and gentleman, welcome on board this Great British Air flight 287 to Barcelona.
Welcome on board, Mr. Dallas.
Dr Jackson, welcome on board the Prometheus.
Welcome on board, Mr. Thevenet.

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.