A Sacramento company has lost its contract with the U.S. Forest Service to provide firefighting aircraft.

The agency announced Friday that it had canceled the contract with Aero Union Corp., with operations based at McClellan Field.

The company signed a contract in 2008 to provide the Forest Service with exclusive access to six Lockheed P-3 tanker aircraft for firefighting purposes. The five-year contract required Aero Union planes to pass a regular airworthiness inspection program.

In April, Aero Union informed the Forest Service that the Federal Aviation Administration found the company was not in compliance with that inspection program.

"We can't in good conscience maintain an aviation contract where we feel lives may be put at risk due to inadequate safety practices," Tom Harbour, director of the Forest Service's Fire and Aviation Management program, said in a statement.

Aero Union could not be reached for comment.

Forest Service spokeswoman Karyn Wood said the agency plans to move six aircraft from Alaska to the lower 48 and will seek a new contract in August to replace Aero Union.

The development comes at a risky time for fire safety in California and the West. The Forest Service asserted it has adequate aircraft remaining under contract to meet its fire protection needs. According to its statement, that includes 21 tanker aircraft to cover the entire nation, 13 of them under contract to the Forest Service and the remainder operated by the military.

Timothy Ingalsbee, executive director of Firefighters United for Safety, Ethics and Ecology, said the aircraft coverage may be adequate now, because fire activity is relatively low across the country, except in the Southwest.

"I do support their decision, because that is one of the highest-risk jobs in firefighting," Ingalsbee said of the air tanker work. "This is a very gutsy call by the Forest Service, and I have to assume it came in desperation."

David Wardall, a board member of Associated Aerial Firefighters, an advocacy group for pilots and other workers in the industry, said California has adequate air tanker coverage thanks to the 23 planes in the California Department of Forestry and Fire Protection fleet. These planes also work on fires that occur on federal land, he said.

"Right now, because of the lack of air tankers in the Forest Service, approximately half the flying of Cal Fire air tankers is on federal fires," said Wardall, who lives in Ione. "The problem would be in the national forests outside of California."

Editor's note: The headline on a previous version of this story incorrectly stated that California, not the U.S. Forest Service, canceled the contract.

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