Who's the Boss?
Burning fiercely and stoked by wind, a white pine snag spewed embers into an unburned stand of spruce and tamarack. Rooted into a remote outcrop of the Canadian Shield in northeastern Minnesota, the old pine faced an unbroken expanse of fuel. The lightning-ignited wildfire had potential and the flaming snag needed to fall, but it was too dangerous to approach with a chain saw.
A light helicopter and a Fire Boss — an 802 Air Tractor on floats — were working the incident under the supervision of an air tactical group supervisor. The initial-attack incident commander on the ground radioed a request for the Fire Boss to target the snag.
The aircraft roared in low and fast, and the first drop caused the top of the pine to sway on a fiery hinge about two-thirds up the trunk. The second drop — from the opposite direction — broke the tree, and the top crashed to the ground. The rain of embers ceased, allowing a sawyer to safely access the remnant of the snag. Although the Fire Boss is not designed to compete with Class B fallers, in the proper niche it's a flexible and effective suppression tool.
North American wildland fire managers are familiar with the 802 Air Tractor as a conventional wheeled single-engine air tanker, or SEAT. But for the 2007 and 2008 fire seasons, the Minnesota Department of Natural Resources Division of Forestry contracted for an Air Tractor on floats to take advantage of the state's thousands of lakes as water sources for aerial assets. The Division of Forestry already owned two Canadair CL-215 amphibious aircraft that have been extremely effective in the Great Lakes states, Ontario and Manitoba, eclipsing what conventional heavy air tankers usually are able to accomplish. As a scooping aircraft, the Fire Boss was expected to contribute seamlessly to the mix.
Being able to reload air tankers on scene without returning to an airport is an obvious plus. Typically, the Fire Boss will deliver the first load from a base — usually a lighter, 500-gallon amount — then reload at the nearest scoopable water source. With fuel burn-off, the payload increases. Sporting a 380-gallon fuel capacity, the Fire Boss may be able to spend more than three uninterrupted hours over an incident. The time advantages don't stop there. For example, land-based air tankers may require 30 to 60 minutes or longer to load and return. For the Fire Boss, that span may be as little as two minutes if an appropriate lake is a mile away, five minutes if the source is 10 miles away and 10 minutes if 20 miles distant.
The scooping probes are incorporated into the floats and can be deployed at flight speed. (The probes for the CL-215s are in the hull.) Filling can take as few as 14 seconds. Once a predetermined load is in the 800-gallon tank, the probes automatically retract. On smooth water at 2,000 feet International Standard Atmosphere (ISA), from 50 feet of altitude going in to 50 feet of altitude going out, the aircraft needs about a 7,000-foot length of run, not necessarily on a straight path. It can maneuver around obstacles, and there have been no reports of conflicts between scooping operations and boat traffic.
The drop pattern is much narrower than that of a CL-215 — by one-third to one-half — providing what some air tactical group supervisors call a more "surgical" impact. The effective width will vary with aircraft altitude and wind conditions, but a general rule of thumb is 40 to 50 feet. Length of drop is often more relevant to ground firefighters, and in field trials conducted by the Division of Forestry, a Fire Boss drop at coverage level one (1 gallon per 100 square feet) was measured at about 660 feet. At coverage level three (3 gallons per 100 square feet), it was just shy of 500 feet.
The Fire Boss can carry about 80 gallons of Class A foam concentrate and, like the CL-215, provide incident commanders with "snowfall" if requested. Dosage, of course, is critical. A mixture of 0.5 percent or less can be an adequate direct-attack concentration where the goal is to provide a wetting agent as opposed to a blanket of bubbles. At the end of a foam operation, the aircraft usually will deliver a rinse load to the fireground. In Minnesota, a 300-foot buffer from lakes and streams is maintained when dropping foam solution.
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