CASPER, Wyo. -- A federal judge is considering a request to dismiss a lawsuit against former aerial firefighting giant Hawkins & Powers Aviation and others over a fatal Colorado plane crash nearly four years ago.

The lawsuit was brought in 2004 by relatives of the two men killed when a wing of one of the company's air tankers snapped off while fighting the 1,200-acre Big Elk Fire near Estes Park, Colo. Pilot Rick Schwartz of Ulm, Mont., and co-pilot Milton Stollak of Cathedral City, Calif., died in the July 18, 2002, crash.

The suit names the company, Hawkins & Powers employees and a host of others and claims, among other things, negligence and wrongful death. The families seek unspecified damages.

On Thursday, attorneys asked Chief U.S. District Judge William Downes either to dismiss the entire case or to drop certain defendants, such as the U.S. Forest Service, from the matter.

An attorney with the U.S. Department of Justice said the Forest Service, which contracted with Hawkins & Powers for use of the air tanker in fighting wildfires, had no obligation to supervise the plane's maintenance.

Attorneys also argued that some responsibility for monitoring the planes lies with the pilots who fly them.

But attorneys for the families told the judge that "chain of command" is an issue and that pilots faced threat of firing if they didn't fly.

The air tanker crashed because of a crack that started at a half-inch rivet on its left wing and spread, according to a Forest Service investigation.

The Forest Service report identified the cause of the Consolidated Volte PB4Y-2 crash as fatigue and failure of the left wing's forward spar, a unit that helps hold the wing to the fuselage.