This lineman is in the process of climbing from the energized transmission phase conductors (bundled conductors) to the helicopter after performing some maintenance on the conductors.
He is wearing a ‘hot suit’ and climbing harness. He is reaching out with a conducting rod which controls the charging arc that flows to the helicopter. Note that the helicopter is not grounded to the earth with any type of conductor. The arc that develops is totally due to the charging capacitance of the surface of the helicopter which is in the presence of the electric field of the energized transmission line. You can think of this like what would happen if a really large bird flew up to sit on the energized power line conductor. It would draw a charging arc as soon as it got close enough to ionize the air molecules (approximately 3kV/mm).
After contact is made, the lineman will use the clamp with the black handles to connect the helicopter to one of the conductors. The worker will then transfer his tool bag and climb to the helicopter.
After he has climbed aboard, he will use the rod again to touch the conductor and then disconnect the clamp. Then, as the helicopter begins to move away, the arc current will be controlled with the rod until the length becomes great enough that the arc self-extinguishes. Then they fly off to the next span that needs a repair.
If this worker was not wearing the conductive suit or using the arc control rod, he would ABSOLUTELY get shocked if he were to touch the helicopter with his bare hand