Uhm BlauK, here's how it works...
A pilot that has 30 kills and survives the war has 30 kills to 0 deaths. Therefore he acquired 30 kills and didn't die. That's 30 kills for his "career". Thus he hasn't died at all, so he 30 kills on his record. This is 30 kills, 0 deaths. Simple math: You can't divide by 0. Therefore he has a 30:0 kill/death ratio... well that still means he had 30 kills throughout his career.
A pilot that has 30 kills but dies during the war has 30 kills and 1 death.
30kills to 1 death ratio
30:1 kill/death ratio. He died once (one life), but he still accrued 30 kills. Therefore he has 30 kills throughout his career but he died.
They both got the same number of kills, but one died and the other guy lived.
See how it works?
-SW