Last week, four U.S. Senators asked the General Accounting Office to review the Forest Service’s efforts to develop an air tanker plan to replenish their air attack fleet.

The senators’ questions came on the heels of a recent letter from CAL FIRE Director Ken Pimlott expressing his concerns about the strategy.

Sen. Ron Wyden, D-Ore., said he and the other senators had “concerns that the federal agencies responsible for responding to forest fire fires — the Forest Service and four agencies in the Department of the Interior — do not have the appropriate number and mix of aircraft that will be needed for fire suppression operations.”

The senators referred to the erosion in the fleet of firefighting tankers since 2002. In his press release, Wyden said the number of air tankers available to federal firefighting agencies has fallen from 44 in 2002, to 19 in 2009, to 14 in August 2011.

In March, Forest Service Chief Tom Tidwell told Wyden 11 tankers would be available this fire season. “We’re short eight air tankers this year,” Tidwell said on March 6, when Wyden asked how the agency was preparing for what might be a “perfect storm.”

In its air tanker modernization strategy plan submitted to Congress in February, the Forest Service reported that it expects ten of its 11 air tankers to be retired by 2021. Their average age is more than 50 years.

“Our meeting was very positive,” Pimlott said. “The Forest Service does understand our concerns.” He also added that the Forest Service has committed not to adversely impact California’s ability to suppress wildfires on both federal and state lands.

Among the questions which legislators raised were whether the agency used an appropriate strategy to evaluate the number and types of aircraft needed to meet wildland fire challenges, whether these approaches were comprehensive and whether the agency has adequately analyzed how to optimally integrate the available locations and mix of airbase opportunities with the variety of aircraft types.

California Sen. Dianne Feinstein was one of four signatories. She has for several years questioned the Forest Service’s progress to rebuild its air tanker fleet.