Still waiting to learn the cause of a large air tanker crash that killed three pilots on a training mission in April, U.S. Forest Service officials are cautiously optimistic that large air tankers will continue to support firefighters through the season.

The April 20 crash of Aero Union Corp.’s P-3B Orion tanker near Chico, Calif., killed Brian Bruns of Minden, Nev.; Paul Cockrell of Fresno and Tom Lynch of Redding -- and renewed fears that the few large air tankers returned to service just days earlier might be grounded again. Last year, the Forest Service and U.S. Department of Interior cancelled all contracts for large air tankers citing safety concerns after two planes broke up midair. The Orion was one of just 10 air tankers approved for service on April 18.

Forest officials are awaiting more information about the cause of the crash from the ongoing investigation by the National Transportation Safety Board. The NTSB’s preliminary investigation of the crash site indicated that “all of the aircraft structure was accounted for at the wreckage site,” a sign that the accident wasn’t caused by structural weakness.

According to NTSB spokesman Paul Schlamm, investigators usually conclude their investigation in six to eight months. The preliminary report of the crash is posted on the NTSB Web site (scroll down to April 20), and investigators will post more information as their work progresses, Schlamm said.

Pending more information from the NTSB, the remaining large air tankers under contract will keep flying, said Rose Davis of the National Interagency Fire Center. “Seven of them are P-3 Orions that we have operational service life data on, and the other three we don’t have that information, but we have them wired up with monitoring equipment, so we’re going to take the risk of returning them to service so we can gather data on the firefighting environment.”

Davis said the Forest Service paid for an engineering study for the P-2Vs, and was hoping to get those results in early June. “We may see enough data to give us confidence in returning the P-2Vs back, but nothing is a given. Safety is the bottom line, and [having] some sort of confidence that they’re safe to fly.”

In January, the Forest Service began soliciting bids for 20 large air tankers for this year’s wildland season. To win a contract, operators must produce a paper trail documenting the aircraft’s service life and establish the number of hours each aircraft can be expected to operate safely. Inspectors must also clear the tankers before they’re eligible.

“We opened the door to 20 and should enough data materialize that we’ve got confidence in the safety, then others that put in bids could be awarded a contract,” said Davis. “The other factor is how much those bids are for. If they’re totally out of proportion with what they should be charging us, then we have the choice of turning them down even if we have confidence in their safety, because they’re not a value to the government.”

In addition to the 10 large air tankers on contract, the Forest Service fleet also has more than 70 single-engine air tankers and 700 helicopters, Davis noted, “so we’ve got the resources to work through the fire season and we’re going to use those resources to get those fires out.”

But some called the shortage of large air tankers a “crisis” in what may be another heavy wildfire season and urged the use of foreign air tankers to help fight American wildfires. Rep. Dana Rohrabacher (R-Calif.) sharply criticized the Forest Service for relying on a “handful of contractors” to supply air tankers, when offers from Russian and Canadian wildland officials were on the table. “The U.S. Forest Service regulations establishing the requirements for airplane-based firefighting are obviously designed to protect the good old boys and to discourage anyone else with new approaches and new alternatives,” said Rohrabacher, testifying before Congress April 26. “I am suggesting that the U.S. Forest Service drop its obstructionist policies that have prevented, among other things, the use of foreign firefighting aircraft to extinguish major fires in the United States.”

According to a report in the Los Angeles Daily News,the Russian Ilyushin-76 Waterbomber can soak an area the size of 12 football fields with one 10-second drop of 11,000 gallons. That’s about four times the capacity of the largest American air tankers.

Rohrabacher said the Russian Waterbomber has played a significant role in extinguishing large fires in Australia, Greece and elsewhere and could arrive anywhere in the world within 24 hours. “Yet the U.S. Forest Service has blocked the Russians from providing their services here, even as we endured massive fire destruction in places like Florida, New Mexico and in California,” he said.

Davis said it’s not that simple. “The main thing is that’s not up to us completely,” she said. “These aircraft from other countries have to be certificated [sic] by the Federal Aviation Administration in the United States to fly for whatever operation they’re going to fly, whether it’s agriculture -- which is generally what air tankers are. That would be the first step. Before we’d even look at them, the FAA would have to tell us that they’re legal to fly in this country.”

Davis noted that the Forest Service is looking at several new ideas to update its fleet of air tankers. It’s currently in discussions with Evergreen International Aviation of McMinnville, Ore., which has equipped a Boeing 747 as a “supertanker” for wildland firefighting. It has a tank capacity of 24,000-gallons (see www.evergreenaviation.com).

The Forest Service is currently awaiting an operational assessment of the Evergreen aircraft, Davis said. It’s weight and large size are of concern. “We’ll have to see. That’s what the operational assessment is for: What can it do? Where can we use it? Can it land on our tanker bases? Some of them may not have runway weight strength to hold it. So all those things still have to be assessed on the aircraft.”

Davis said companies with ideas for air tankers that the Forest Service is evaluating include Minden Air of Minden, Nev., which is developing the BAE-146, a British Aerospace jet, as wildland jet tanker, and another company she declined to name. “Another contract is looking at some of the engineering data on the Douglas products, the DC-4, -6 and –7, so that may materialize in the next couple of months,” she said.

Correction
An earlier version of this story incorrectly attributed information about the Russian Waterbomber to a report in the Los Angeles Times. The report cited was in the Los Angeles Daily News .