Translation:It is necessary that you do not wake up during the flight.
I couldn't agree more.
It seems that there are many ways and degrees of expressing necessity in Turkish, and I guess this is why we are seeing these structures with "It is necessary..." at this point, instead of "should/shouldn't" or "must/mustn't".
Still, introducing unnatural English sentences is hardly the right way of pointing out the differences between the various Turkish expressions.
'you don't need to wake up during the flight = Uçuş sırasında uyanmana gerek yok.
they are different i guess. the turkish sentence say ''uyanmaman lazım'' it means something like''you must not wake up/ you should not...'' but if you say ''you don't need to wake up'' , it is like you dont need but you can.