All these pictures are the worst cases if you check your gear before you shoot things like this wouldn't happen. Carbons are not either straight or broken well ok the are either straight or broken except if not checked they can be straight but broken with faults and thats when accidents happen. Remember Murrphy is always there. Here is a link to easton's website and it's got three different archery pro's Chuck Adams who tells us why he feels Aluminums are the best, then Randy Ulmer stating how aluminum/carbon arrows are the best. Finally Joe Bell tells us how straight carbon is the best. They all have test to back things up but IMO Chuck has the best info and facts. Some of you might have read this article in Bow & Arrow hunting mag.
http://http://www.eastonarchery.com/articles/aluminumaremyfav.asp