See video. As helicopter approaches high-voltage transmission line, the worker is holding out a probe; at 0:15, when it gets within the final couple of feet of the wire, there’s some arcing, and after the probe finally makes contact, the worker leaves the helicopter and gets onto the line.
What is the probe for, and what’s with all the arcing? The helicopter is ungrounded - it’s hovering several yards above the ground. It’s not about static electricity, or helicopters would do this every time they landed. The line is presumably AC, so the voltage is fluctuating back and forth, so they surely aren’t trying to bring the heli to the same potential as the line. Except that sure does seem to be the case.
So what gives? Why is there arcing between the probe and the line?