I’ve just failed a helicopter S&R mission, as the victim was embedded in tall trees and the nearest clearing was over a mile away. I did try to land at that clearing and walk, but as soon as i got a few hundred yards from my helo, the mission got failed.
When I touched down, the victim marker was 1.33nm away, so it would have been a hefty uphill trek anyway. 
If Career mode is going to do ■■■■ like this, they’re either going to have to create a clearing, within spitting distance of the victim, or provide a landing opt out, and let the ground crew recover the hapless victim.