"Five people were killed in an airplane crash."

Is it possible to use causative + passive öldürüldü in the corresponding Turkish sentence? If the simple öldü was used would it sound out of place? What about vefat etmek, could it be used when reporting an accidental death? (Suppose the sentence was in a newspaper.)

Just out of curiosity, is there a special verb for those who die in the battle field?

No.

öldürüldü = he/she was killed (by somebody not by accident)

"vefat etmek" usually means to die of natural causes (e.g. aging or some sickness).

"şehit olmak" is used for those who fought for their country against an enemy and died in the battle field.

Simple "öldü" is ok for plane crash.

Uçak kazasında beş kişi öldü.

What is really strange here is the English use of kill. I never paid attention to it until I tried to translate it into Turkish... Just like the accident was personified.

Many kinds of euphemisms are used in languages when death is the issue. Good to know ölmek is not a word too harsh for normal use.

si++, thank you.

"Hayatını kaybetmek" [ to lose one´s life] can be used too.

"Five people were killed in an airplane crash."

"Uçak kazasında 5 kişi hayatını kaybetti."

Sure.

Btw, in the news of today´s plane crash they expressed it using the other way round:

127 kişiden kurtulan yok.

İslamabad yakınlarında düşen uçaktaki 118 yolcu ve 9 mürettebattan kurtulan olmadığı belirtiliyor.