We just became aware of another air tanker study that the U.S. Forest Service commissioned. By our count this is the 13th federal study on the use of air tankers since 1995, and was one of three completed in 2013. (A list of the studies is at Wildfire Today.)
Titled Large airtanker use and outcomes in suppressing wildland fires in the United States, it was written in 2013 and published in the International Journal of Wildland Fire in February, 2014. The document maintained a low profile, possibly because it was behind the journal’s pay wall, rather than being an Open Access document.
The study attempts to determine how effective large air tankers (LAT) have been at preventing fires from escaping initial attack (IA). The authors begin by describing the poor data that they used to develop their conclusions. For example, the sparse data made it very difficult “to track drop location and time, to associate drops to specific fire events, to gather information on the fire environment (fuels, weather, terrain, etc.) at the time of the drop and, critically, to clearly identify mission objectives for each drop.”
The authors used some convoluted methods to make guesses about which retardant drops were on IA fires and which ones were not. And, “due to data availability issues” they only considered stats from two years, 2010 and 2011. In 2010 there were 19 LATs in the fleet at the beginning of the year and 14 in 2011, but by the end of 2011 the study reports there were only 10 available.
Since the air tanker fleet has atrophied from 44 in 2002 to as low as 9 in 2013, it has been impossible to always produce a LAT every time one is needed on IA. And if it does show up, the chances of it arriving while there is still a chance to slow the spread, enabling ground based firefighters to contain the fire, are not as great as they were in 2002 when there were almost five times as many air tankers.
The authors addressed the timing of air tanker drops:
Therefore, the determination of whether or not a fire will benefit from LAT drops in IA will be directly related to the delay from ignition to drop occurrence. This delay allows a fire to grow and cross a critical threshold where fireline production of IA resources cannot catch the growing fire perimeter. When evaluated in this light, the demonstrated low success rate for IA containment could be addressed by reducing the time between ignition and LAT arrival on these fires with a high potential to escape. This would require an improved ability to rapidly recognize an individual fire’s escape potential so that LATs are ordered very early in the event. Further, this suggests that if we can improve our ability to identify when and where these types of ignitions are likely to occur we should be able to effectively pre-position LATs before an outbreak of fires. If the IA success rate could be improved through such a system, overall LAT demand may be reduced because many of the evaluated drops were associated with IA fires that ultimately escaped.
And they wrote about the resistance to control of fires that receive retardant drops on IA:
That the rate of escape associated with fires that receive drops during IA is so high – far higher than the general escape rate of approximately 2 to 5% – is strongly suggestive that LAT use, when it does occur in IA situations, occurs on the more difficult fires (i.e. Category C fires as defined by Keating et al. 2012)
The “Keating et al 2012” report is more commonly known as the Rand Report.
They also make the point that although the USFS’ policy is to prioritize LAT use on IA rather than Extended Attack (EA) fires, a high proportion of LAT drops occur on EA fires.
In spite of these conditions, the authors apparently felt comfortable making the following statement in the paper’s introduction:
Results suggest that containment rates for fires receiving large airtanker use during initial attack are quite low.
A statement like that when taken out of context, or without understanding the limitations of the report’s data, can be very misleading.
If air tankers are going to be effective in IA, first they have to be near enough to the fire to arrive, preferably, within 15 to 30 minutes after being dispatched. And, they must be dispatched if not at the first report of smoke, at the first confirmation that there is a wildfire. If there is a delay until a fire officer arrives at the scene to make the decision to order aircraft, that could be the difference in effective or ineffective air tanker use.
As we have stated many times, the prescription for keeping new fires from becoming megafires is:
Rapid initial attack with overwhelming force using both ground and air resources, arriving within the first 10 to 30 minutes when possible.
Below is a graphic that we put together showing the Unable to Fill rates for LAT requests, the number of LAT requests, and the size of the air tanker fleet since 2002.
(The chart above was revised February 3, 2015 to include data from 2014.)