USA — If Evergreen International Aviation has its way, 747s will be added to the fleet of aircraft dedicated to fighting wildland fires in the coming season. Oklahoma-based Omni Air International, has proposed using a McDonnell Douglas DC-10 it has modified to carry up to 12,000 gallons of water, about half the payload of the 747. Both proposals emphasize the effectiveness of the increased capacity such aircraft have for carrying retardant that is dropped on wildfires. Either would work in concert with ground crews and other tanker aircraft already utilized.
U.S. Forest Service Interagency Airtanker Board is currently discussing such matters. Conventional air tankers can only deliver up to 3,000 gallons of water, foam, gel or other retardant on a fire before returning to a base for reloading.
The supertankers would add more range and reduce time between drops. Federal land management agencies have not advertised for bids to supply firefighting supertankers, but after the two companies approached the Forest Service with prototypes, the agency conducted a ‘Supertanker Operational Assessment Project’ to determine whether the larger jets would be an asset. The preliminary results from flight tests conducted for the Forest Service study show the supertankers can fly low and slow enough — a 747 demonstration drop near the National Interagency Fire Center was at 400 feet altitude at 140 knots — to effectively target wildfires without interfering with ground attack operations.
Conventional air tankers frequently fly as low as 200 feet above a fire and use gravity to deliver water or retardant. The Evergreen supertanker has a new pressurized dispersing system that shoots retardant out of nozzles on the plane’s underbelly, allowing the jet to fly higher over a fire and still effectively deposit suppression material on the ground.
The interagency team evaluating the potential use of supertankers has yet to complete a cost-benefit analysis. The federal government and the companies developing the planes have not negotiated a price for what is expected to be a one-year interim contract to evaluate the aircraft in service this summer.