Accidents.

This is coolbert:

Without question the military profession dangerous at all times. Combat aviation pilots and aircrews NOT even in contact with the enemy their fatality rate quite high.

As was noted at an Internet web site:

"millions of men had to risk their lives in WWII and were thus nervous about how they would respond to danger. (And it wasn’t just combat that could kill them, but also training and transportation. Here’s a statistic I have heard but haven’t seen confirmed, but it sounds plausible: 30,000 American troops died during WWII in non-combat airplane accidents: that’s like a packed 737 going down every week.)"

To which we can add the comment of an acknowledged aviation authority:

"I've read the loss figures--seems like 1/3 of combat planes from the US never made it to the front from accidents, 1/3 got shot down or otherwise crashed during combat ops, and perhaps 1/3 survived to make it to the wrecker's ball afterwards.  Something like 120,000 planes made in the US, and 40,000 lost to accidents". 

"A PACKED 737 GOING DOWN EVERY WEEK" AND DOING SO FOR A FOUR YEAR PERIOD!

Front! Where is the front? For the combat aviator the front is anytime he gets into the cockpit of a warplane.

coolbert.