I completly agree with everything you said except for the statement that water not effective. From what I understand Tankers put a line around (to contain) or accross (to direct) a fire. Then the Helos and the Scoopers come in and basically increase the relative humidity in the fire environment by dropping on or near the fire. Once the fire has backed off enough the ground crews go in and put it out.
The larger air tankers are the weapon that we are missing here in Australia.
Please correct me if I am wrong
Fire isn't fought that way, and tankers don't work that way. Air assets don't fight fire. Ground troops do.
Tankers are used to flank or work parts of a fire to contain it's direction or slow it's rate of spread while ground troops work the fire. Retardant lines may be used to reduce rate of spread or encourage the fire to move in another direction based on wind, natural barriers, vegetation or types of fuels, topography, slope, aspect (north/south, etc), and of course, threats to persons, structures, etc. Considerations include resources available to back up retardant lines, ground resources, turnaround times, etc.
One of the single most common, and most basic mistakes in retardant application, is to attack the head of the fire, or to go direct on the fire. Without an ability to build line rapidly with short turn-around times or ample air assets, the result is invariably splitting the head of the fire into two or more parts, increasing the rate of spread, and complicating the fire. Most of the time, this only increases fire activity, wastes retardant, and makes the fire worse.
Water cools fire directly, but cooling the fire is the least effective way, and most wasteful way, of controlling it's activity. Unless it's a small spot fire, then water doesn't put the fire out. Water and foam are short term measures, often most effectively used on small spot fires. Where water can be used in extended attack operations, it has to be available in very large quantities, and enough resources need to be present and capable of acting, which can keep a constant application of water on the fire. Scoopers, for example, must have the ability based on proximity of an uplift source, a short distance, and enough scoopers, to keep putting water on the fire every few minutes. Otherwise, the water is usually nearly worthless.
One must remember that in an active wildfire, temperatures above the fuels can exceed two thousand degrees Farenheight, and fuel temperatures and fire activity can mean that water dropped on an active flame front may do little more good than spitting in a camp fire. Water evaporates quickly, any cooling or loss of energy in the fire is quickly replaced and reheated, and the change in relative humidity is so minute that it's negligible in character.
Relative humidity of it's own accord does reduce fire behavior somewhat in intensity and rate of spread, but is a minor consideration compared to winds, slope, fuel moisture, etc.
Fuels on the ground are classed by the amount of hours required to effect a change in fuel moisture. Some fuels such as grass are one-hour fuels, but many fuels over 3" in diameter, like small tree branches, are into the thousand hour range. The introduction of local temporary changes in RH produce insignificant changes in the fire behavior for the most part, and no changes in the fuel moisture. Even a rainstorm only produces brief changes, and doesn't effect fuel moistures save for grasses and other one-hour fuels; the result in controlling fire spread isn't great.
I've chased a fire with retardant up to a lake, in Florida. I ran retardant down both flanks of the fire until the head ran into the lake and the fire ended. A week later we were back on the fire again. Same fire, other side of the lake. It continued to burn under the lake, came up on the other side, and kept running as a wind-driven fire. It was more intense on the other side and took more resources to control.
Fire won't "back off" by dropping scooping aircraft and helo buckets nearby. Nor do ground troops wait for a fire to "back off." Air assets are tools that ground troops request or use to apply to specific parts of a fire, in order to assist them in working the fire. Ground troops often work the fireline directly with shovels, pulaski's, handlines (hoses and water or foam), lighting backfires or backburns, running dozer or cat lines to cut away fuels and create fire breaks, and other tactical methods of fighting fires. In accomplishing this mission, they may request a helicopter to put water on a hotspot or to work a segment of a flank. They may look for a retardant drop to back up a bulldozer line or a road, to prevent spread across the road. In each case, the retardant use or water use is only one tool of many that the ground troops have at their disposal when working the fire.
I've spent many years as an IA, or Initial Attack pilot. I'm often the first one on scene, and in some cases, I do end up working the entire fire from the air. My efforts are always considered a temporary measure, however, until someone can get on the ground and work the fire. Even if it's a single tree. I may put a box around it or cross it with two retardant lines, but all I'm doing is buying time for a helattack team or hotshots to come in and hit the tree with a chain saw, dig a line around it, or do whatever is necessary to actually control and put out the fire.
Often as not, the most effective means of putting out a fire is to supervise it burning itself out. Air assets are put in use to attempt to reduce damage to danger to structures of personnel until that happens. A lot of fires are far beyond the capability of man to control, or extinguish, and firefighting efforts, both in the air and on the ground, are futile motions that take place in earnest, until nature decides enough is enough.
Large air tankers are one tool in the toolbox...but only one. You need not only the aircraft, but enough bases capable of supporting them, close enough to fires, spread throughout the country, to do some good. Some years ago in the US, in Florida, significant fires raged throughout the state. Early in the game, I was in the only large air tanker in the state. Other resources were enroute, but we found that with a temporary base set up in the City of Ocala, we had an hour to the fire. A flame front with 250'+ flame lengths was wind-driven, threatening structures, and moving fast...and two miles wide. Our retardant line with a heavy coverage level extended just a little over a hundred yards, using a large air tanker with a 2,000 gallon capacity.
The result was that the fire burned over our line before we could load and return with more retardant, and we were effectively wasting our time. The State of Florida wanted us to keep dropping however, because often as not it's as much a matter of public relations as it is doing anything effective. It was a given that we couldn't control the fire, but it was important that the public felt like every effort was being made to do so.
While Australia may be missing large air tankers, they aren't the be-all and end-all of firefighting...and such a lack doesn't mean that firefighting can't be effective. Getting a large air tanker program doesn't necessarily mean that you'd see a change in your fires there, either. Oz is a large place, with few airfields and long turnaround times. Even large air tankers put down very small lines of retardant when considering the amount of fireline that may be burning and the activity it may produce. Large air tankers can be effective tools, but are an insignifcant spec in the face of mother nature.