The Chinese translation of have a nice trip in Chinese is simply have a nice trip. This statement is usually said to the people who are travelling.
I do not know the phonetic answer but in simplified Chinese it is: 有一个愉快的旅程, in traditional Chinese it is: 有一個愉快的旅程.
Have a nice trip! = Miłej podróży!
nice day
Have a nice trip = Bon voyage! (Not sure what you mean by "When you are flight".
¡Buen viaje! (Have a nice trip!)
Buon viaggio.
bon voyage!
Perverted... -_-
Xinghui.
旅行怎么样
好梦 "Hao Meng"
旅途愉快/Lǚtú yúkuài
Thai is the dialect of Chinese spoken on the Taiwan, or Chinese Taipei. To say "have a nice day" in Thai one would say the phrase "khx hi mi khwam sukh mak ni wan ni na".