Federal investigators have recovered a cockpit voice recorder from the air tanker that crashed in Utah and killed two pilots fighting a wildfire.

The recorder survived the crash intact and was sent for analysis to a Washington, D.C., lab, National Transportation Safety Board supervisor Debra Eckrote said Friday.

NTSB investigator Van McKenny also recovered a black box that monitors engine performance, but Eckrote said that box was damaged and may not yield useful data.

The tanker was reduced by Sunday's crash on a mountain slope to fragments that revealed few clues about the crash, she said.

That makes the cockpit voice recorder all the more important in determining a cause.

"It looked to be in good condition. Cockpit voice recorders can withstand very severe forces," said Eckrote, a deputy regional NTSB chief in Seattle.

In Washington, D.C., NTSB spokesman Nicholas Worrell said Friday that the voice recorder had arrived at the lab. He said he didn't have any information about its contents.

U.S. Forest Service contractor Neptune Aviation Services of Missoula, Mont., has said the voice recorder could have captured conversation with the pilot of a smaller aircraft that was guiding the Lockheed P2V tanker on drop runs.

The lead pilot didn't witness the accident, however, because he was flying ahead of the tanker.

The tanker crash killed two pilots: Todd Neal Tompkins and Ronnie Edwin Chambless, both of Boise, Idaho.

Eckrote said the NTSB wants to recover the tanker's wreckage for a closer inspection, but the White Rock wildfire has kept a salvage company from going to work.

The salvagers were dispatched by Neptune Aviation's insurer.

U.S. Bureau of Land Management spokesman Chris Hanefeld, who is tracking the White Rock fire, said the tanker crashed into a mountain slope a quarter mile inside Utah from the Nevada-Utah border, on the fire's southern edge.

The lightning-sparked has scorched 10 square miles and was 90 percent contained on Friday, officials said.

About 215 people, including support staff, are mopping up the fire and holding fire lines with help from a helicopter, six fire engines, a bulldozer and two water tenders.