Why does an aircraft have to be flying straight and level to facilitate a jump? In the other questions about parachutes on this site, it has been stated that the aircraft would have to be flying straight and level to facilitate a jump. However, there were quite a few pilots during WWII whose planes were not flying straight and level and who still managed to escape. 

Is there a difference between then and now that I am not catching?
One of the reasons why many WW2 pilots did not make it out were the G-forces and acceleration in directions other than the door when they had to get out. The bailing out survival rate appears to be correlated to the ease of exit. 

If you're going to have a smooth and safe departure, you're happiest doing it during level flight when there's no interference from plane motion.


(source: lonesentry.com)