It takes about 3-4 days to take a wounded soldier back to the united states depending on the state of the soldier which depends on how fast they can take it and the type of plane that they're flying with the conditions they are flying are also factors. Depending on the route, avoiding war zones when they fly home won't always be a straight path back home. It takes longer because of some injuries, such as back injuries, you can only have so much movement from the plane, and too much movement could cause harm to the injured, such as being paralyzed.