Re: How can there be an arc from power line to lineman on ungrounded helicopter

The arc is from the 'copter to the tranmission line.

There's a movie called, "The Hunt For Red October" that shows and explains 
that effect quite well.  Static electricity.  Like sliding across the car 
seats on a dry day, the rotor of the helicopter picks up a static charge 
that is high enough to require grounding.  The lineman would prefer that 
that discharge not go through him. 

Even though we say it's a 115 kV transmission line, that is an AC voltage 
that compared to earth-ground AVERAGES zero volts.  The voltage between 
the helicopter and ground is DC and is very high.  High enough to cause an 
arc which takes a voltage of about 75 kV per inch of air, if I remember 
correctly.