In this episode of “Ask Hyojin”, Hyojin explains how to say “Have a safe flight” and “Take care” in Korean.
to be safe = 안전하다
flight = 비행
So the translation can be “안전한 비행 되세요!” or “안전한 비행 하세요!” But in more natural Korean, you don’t really say that. When their friends go abroad on an airplane, people say “여행 잘 다녀와.” more commonly. 여행 means “trip”, 잘 means “well” and 다녀와 means “Go and come back”.
“Take care” can be translated to “몸 조심해. (Be careful. Take care of your health.)” or “잘 지내. (Be happy and live well)” but it’s only when you say good-bye to someone you will not see for a long time. If you just want to say “take care” more casually, you can simply say “안녕”.