The Forest Service and the Interior Department terminated contracts with private companies for use of the planes after the National Transportation Safety Board determined their airworthiness could be not assured. Three such planes crashed between 1994 and 2002, killing seven crew members.
Forest Service Chief Dale Bosworth said that, in the wake of the NTSB report, continuing to use the tankers posed ``an unacceptable risk'' to aviators, ground firefighters and communities near the blazes.
The fixed-wing planes, some of them as old as 60 years, had been used primarily in initial attacks on fires and protecting buildings when fires were moving toward urban areas, said Dan Jiron, a spokesman for the Forest Service.
He said the government still has the use of 491 other aircraft, including smaller fixed-wing planes and helicopters. ``It's serious, but we will be able to do our job,'' Jiron said.
The tankers were each capable of dumping from 1,700 to 2,500 gallons of water a minute.
The Forest Service grounded the fleet of tankers it had under contract after two crashes in 2002.
The planes were reactivated after a new inspection program was developed at the Energy Department's Sandia National Laboratory in Albuquerque, N.M., but the NTSB said in its report last month that maintenance and inspection programs were still inadequate.
``It was apparent that no effective mechanism currently exists to ensure the continuing airworthinesss of these firefighting aircraft,'' the report said.
Complete information on the stresses that the planes endured in firefighting was not available, the report said. Nor was there complete information on maintenance and inspection dating back to the planes' use in the military.
Investigators who reviewed the crashes in California and Colorado in 2002 said the aircrafts' wings could not take the strain. In the California crash involving a C-130A, the wings snapped off and the fuselage plunged to the ground, killing three people on board.
Planes from the now-grounded fleet probably were used to fight a current fire in California, Jiron said. ``We always use what fleet we have available to use,'' he said.
However, the planes were not used on Monday, he said.
Fires also are burning in Montana, Arizona and Minnesota. They are fueled by drought, which has been worsening in many areas in the West, drying pasturelands and leaving forests parched. The National Drought Mitigation Center's Drought Monitor now classifies the West as being in a state of exceptional drought, worse than its initial classification of abnormally dry.
The government will have to shift firefighting tactics with the loss of the 33 planes, Jiron said.
Firefighters will target blazes with helicopters and cropduster-type fixed-wing aircraft, Jiron said. These aircraft can be more accurate than the big planes when they drop their payloads, and they can resupply with water closer to the fire, he said.
The government also can activate eight military C130s equipped to carry water, he said.
``This is a loss, but it is not something we can't address now that the curtain is raising on fire season,'' Jiron said.
To the government, the loss of planes is not an insurmountable problem. Firefighters still should be able to do their inherently dangerous job ``with or without air support,'' it said.
But one aviation officer in the Forest Service, Bill Pierce, called the grounding of the 33 tankers ``a major loss'' that could raise the risks involved with firefighting.
``It's a real hazardous situation, not having the tankers,'' said Pierce of the Humboldt-Toiyabe Forest Service office in Reno, Nev.
