The Forest Service today said it will need newer, faster and more cost-effective aircraft if it hopes to combat increasingly severe wildfires in a warmer, and drier, West.

The agency today released a long-awaited proposal to replace its 50-year-old fleet of large wildfire tankers, which the Forest Service uses to drop fire retardants believed to slow the spread of severe wildfires.

Forest Service Chief Tom Tidwell said the plan calls for turbine-powered tankers big enough to carry at least 1,800 gallons of mixed retardant and capable of cruising at nearly 350 mph.

"We need a core fleet of the next generation large airtankers to supplement our boots-on-the-ground firefighters for what we know will be longer and more severe wildfire seasons in years to come," Tidwell said in a statement. "Not only will these newer, more effective airtankers help us keep fires contained and communities safe, they will also protect our brave men and women on the fireline."

The agency currently operates a fleet of less than a dozen aircraft under contracts with two private firms, down significantly from the 43 tankers it operated in 2000.

Maintenance costs and safety risks have risen as the airplanes age, and all but one of the planes face mandatory retirements over the next decade, the agency said.

Just yesterday, the Missoulian newspaper in Montana reported the discovery of a large crack in the wing of one of Neptune Aviation's P2-V aerial tanker planes during a safety check this winter, which prompted mandatory inspections of all similar planes on Forest Service firefighting duty.

Tidwell said the effectiveness of new air tankers will depend largely on speed and load capacity. Larger crafts can drop larger amounts of retardants, which buys time for firefighters on the ground to safely construct a fireline, the agency said.

"Large airtankers can be effective in thick forest canopies and areas of dense brush or timber," Tidwell said. "A larger load capacity also allows large airtankers to split their retardant loads to support different parts of a fire without delay of returning to base."

The strategy did not identify an optimal number of aircraft for future wildfire needs but cited studies showing that between 18 and 28 aircraft will be needed. It also did not identify a cost for the proposal.

Tidwell took heat from Senate lawmakers last summer over the scope and timeline of his agency's response to the aging fleet.

"This has been almost the longest-running battle since the Trojan War," said Sen. Ron Wyden (D-Ore.) during an oversight hearing before the Energy and Natural Resources Committee. "Why is it taking so long to get an adequate replacement fleet?"

Chairman Jeff Bingaman (D-N.M.) at the time said the cost for updating the agency's fleet would be "quite substantial" and might not be covered from within the agency's existing budget.

A spokesman for Sen. Lisa Murkowski, the committee's ranking member, said the senator is awaiting more details on the plan. The Alaskan Republican criticized the agency for initially limiting its search only to tankers capable of carrying at least 3,000 gallons of slurry.

"The proposal doesn't include enough detail to determine what the cost of the new aircraft would be, and it doesn't pick a specific aircraft type," Murkowski spokesman Robert Dillon said. "Hopefully, we'll know more when the budget comes out next week."

The Forest Service plan comes shortly after the agency agreed to limit its use of fire retardants to ensure they do not harm sensitive plants, animals or fish (E&ENews PM, Dec. 15, 2011).

In the past decade, at least 10 states had wildfires of record-breaking size, the agency said.