It's all about prep and planning. Unlike flight sim they don't just go and weave through whatever environment they want. There are detailed route studies with all obstacles, terrain and towers identified; custom maps made highlighting the safe corridor, climb points and obstacle required to be in sight to continue without climbing. For something live Riverfire they then practice it in a simulator as well.
It's not one wrong move. There is a buffer put into everything they are doing making sure that it would take multiple very specific actions to go wrong, with two people at the controls and two more monitoring their every move.