This is my first and probably last post to this forum - I am just an English lawyer with a hobby interest in aviation. With regard, however to the language of the pilots being "
on a frolic of their own", I too was interested to see it in a modern American legal document. Unless the flow of usage was in the opposite direction, I think that you acquired it from us.
In what is now called Employment Law, and was then called Master and Servant, English courts in the nineteenth century (if not before), developed a doctrine under which a master could be ("vicariously") responsible for harm done by his servant. The master could avoid such liability by showing that the servant was not doing what he was employed to do, and doing it negligently, but was, in the language of the time, "off on a frolic of his own". It became a term of art in the field.
The case of
Limpus v London General Omnibus Co (1862) comes to mind - in which bus drivers were racing each other from stop to stop to compete for passengers and caused an accident. The driver was held not to be on a frolic of his own, but doing what he was paid to do, negligently. Now if only you guys raced each other from hub to hub for the same reason ........
