"Climb the crane to reach the cabin" is an objective in the story mission Scouting The Port in Grand Theft Auto V
Walkthrough[edit]
Get to the base of the crane and start climbing on up it. Take the steps and ladder on up to the top. Once there a Supervisor will tell you to get in the cabin of the crane and start operating it. Trevor will try to talk his way out of it, but the man insist. There is more stuff to move.
