Industrial Underwriters Insurance Company, a Corporation v. P & a Construction Company, a Corporation, and Insurance Company of North America

JONES, Circuit Judge:

This appeal is another of the increasing number of cases involving the question of which, of two or more, insurance companies had liability coverage for an injury to person or property. The facts were stipulated.

On October 28, 1964, P & A Construction Company was engaged in laying a transmission line for and under a contract with Oklahoma Natural Gas Company. In so doing, P & A was using a DC-6 caterpillar tractor, which was equipped with a side-boom or hoist attachment, to unload joints of the precoated and wrapped gas pipe from a truck belonging to P & A which had…