歡迎乘坐(或歡迎加盟) used as a greeting to passengers or to a person joining a new organization, etc.
welcome aboard
「Welcome aboard!」 said the stewardess.
空中小姐說:「歡迎各位乘坐本次航班!」
welcome sb/sb's aboard
The flight attendant welcome us aboard.
空中小姐歡迎我們上飛機。
The office manager welcomed his aboard.
辦公室主管歡迎他來參加工作。