Before someone you know goes on a trip, such as a flight, it is polite to wish them a safe journey. In English, one might use some variation of "safe travels" or "have a safe trip". In Judaism, a person recites Tefilat HaDerech for his or herself, a prayer for a safe journey.
Is there a formal or traditional farewell (perhaps a bracha) that one can give to someone before they leave on a trip?