The four-year exclusive use contracts for Type 1 firefighting helicopters issued in 2016 expire at the end of this month on April 30. Since new contracts based on the solicitation issued November 15, 2019 have not yet been awarded the U.S. Forest Service has given 30-day contracts to a handful of vendors.
After one of our readers told us about the 30-day contracts, I contacted the U.S. Forest Service by email with a list of questions to find out more details, including which purchasing authority was used to issue these unusual aerial firefighting contracts.
Kaari Carpenter speaking for the agency declined the specific requests, only saying, “The USDA FS is utilizing all options available via the existing aviation contracts and Call When Needed Agreements to ensure that historical helicopter coverage remains in place.” A direct appeal to the Forest Service Director of Fire and Aviation, Shawna Legarza, did not receive a response.
Hunt Norris, the General Manager of Siller Helicopters, confirmed that his company received two of the 30-day contracts. Siller operates CH-54A and S-64E Sikorsky Skycranes.
The Type 1 helicopter schedule called for two bases to open on April 12, Sierra Vista, Arizona and Silver City, New Mexico, but those contracts expire April 30. Five bases were expected to begin their season on May 1: Cedar City, Utah; Helena, MT; Porterville, CA; Bishop, CA; and La Grande, OR.
A Siller Helicopters CH-54A (H-781); a Type 1 helicopter. Photo by Siller.
For a number of years the Forest Service had 34 Type 1 helicopters on exclusive use contracts, but that number was cut to 28 in 2017 using the provisions for three 1-year optional extensions. The first two years after the reduction, 2017 and 2018, the percentages of requests for Type 1 helicopters that were unable to be filled (UTF) were 60 and 45 percent, respectively. Last year, 2019, was extremely slow, with the number of acres burned in the lower 49 states being 40 percent lower than the 10-year average. That was reflected in the UTFs — only 5 percent of the requests were not filled in 2019.
Schedule for large air tankers that are on USFS exclusive use contracts, updated March 11, 2020 by USFS.
The U.S. Forest Service has released a days off schedule for the 13 large air tankers that are under exclusive use contracts as we begin to move into the 2020 wildfire season.
The contracts and companies supplying the aircraft are the same as last year but the schedule confirms the administrative bases and the days off. The locations do not mean the air tanker will spend a certain amount of time at that base. Only one of the 13 tankers is identified on the list, Tanker 101, an Aero Air MD-87 with an administrative base at Medford, Oregon that began its Mandatory Availability Period March 12.
Usage of large air tankers, 2000-2019. Revised 2-24-2020. Fire Aviation.
There are so few large airtankers on exclusive use contracts that dispatchers have to guess where fires will erupt and move the aircraft around, like whack-a-mole. None of the tankers this year will be staffed seven days a week, and the DC-10s will have two days off each week. In 2019, 20 percent of the requests for large air tankers were unfilled during a year in which the number of acres burned in the lower 48-states was the least since 2004.
2019 US acres burned, except Alaska. Stats by NICC. Numbers prior to 1983 may not be reliable. Processed by Wildfire Today.
The hourly and daily rates were redacted on the document that the Forest Service released. On the image at the top of the article I cropped off those blank columns to make the remaining information that was not censored more readable.
Usage of large air tankers, 2000-2019. Revised Feb. 24, 2020. Fire Aviation.
(Updated Feb. 24, 2020)
This chart shows data from 2000 through 2019 for the number of large air tankers (LAT) on U.S. Forest Service Exclusive Use (EU) Contracts, the number of times each year large air tankers were requested by firefighters on a wildfire, and the percentage of requests that were not filled (Unable to Fill, UTF).
New Call When Needed contracts
More information is now available about the Large Air Tanker Call When Needed (CWN) contracts that were awarded in December, 2019. Six companies have a total of 36 aircraft on the list, a number of aircraft that is one more than first announced.
The costs below are estimates provided by the Forest Service for one aircraft based on the contracts awarded. Kaari Carpenter, a Lead Public Affairs Specialist for the Forest Service who sent us the information, told us that the estimates assume 36 days a year, for 4 years, and 100 flight hours a year. The dollar figures also include the estimated fuel costs based on each aircraft’s fuel burn rate at a fuel price of $5.21 a gallon.
The companies that were awarded Call When Needed large air tanker contracts in December, 2019. Data from the US Forest Service.
In comparing the dollar figures, note that the listed air tankers can carry up to 3,000 to 4,000 gallons in each load, except the DC-10 and 747 which can hold approximately 9,400 and 19,200 gallons respectively.
Update February 13, 2020. With the very different capacities of the seven models of air tankers receiving the CWN contracts, using just the USFS data above, it is difficult to analyze and compare the actual costs of applying retardant. I did some rough back-of-the-envelope cyphering assuming 3,500-gallon retardant capacities for all aircraft except the DC-10 and 747, and 9,400 and 19,200 gallons respectively for those two very large air tankers. Other assumptions were 36 days availability a year for four years and one load per hour for a total of 400 hours. The approximate, ball park costs per gallon delivered by a Call When Needed air tanker that was awarded a USFS contract in December, 2019, rounded to the nearest half-dollar and not including the costs of retardant, are:
$7.00: MD-87
$8.50: BAe-146, C-130, & 737
$10.00: RJ85
$4.50: DC-10
$3.00: 747
These dollar figures are very, very rough estimates. In some air tankers the amount of retardant varies with density altitude and the amount of fuel on board.
Call When Needed air tankers are usually much more expensive per day and hour than Exclusive Use Air Tankers which are guaranteed several months of work. CWN air tankers may never be activated, or could sit for long periods and only fly a small number of hours. Or, they may work for a month or two if the Forest Service feels they can pay for them out of a less restrictive account.
In 2007 the average daily rate for large federal CWN air tankers was 54 percent higher than aircraft on exclusive use contracts.
And speaking of long time frames, it has been 450 days since the Forest Service published the solicitation for the third round of EU Next Gen air tankers, Ver. 3.0, on November 19, 2018. Bids were required 12 months ago. Ms. Carpenter told us today that the FS expects it to be awarded in “early March, 2020.”
In the hearing 10 months ago Colorado Senator Cory Gardner referred to the study, saying in his rapid-fire speaking style: “There is a technical term I want to use to describe the length of time it is taking to get that study done, and it is bunk! I’m sorry, it’s just a bunch of bunk that it has taken seven years to get this done. We fought a world war in four years, we built the Pentagon in 16 months, we can’t do a study in 2 years, 1 year, 3 years, 4 years, maybe 5 years? It has taken seven years to do this? In the meantime we have western states that have had significant and catastrophic fires. I understand it’s important to get the information right. But doggonnit, someone needs to get a fire lit underneath them to get something done on this study.”
When asked if firefighting aircraft were worth the cost and if they were effective, the answers from land management agencies have often been, “Yes”.
How do you know?
“We just do”. (I’m paraphrasing here).
The study is supposed to quantify the effectiveness of the various types of fixed and rotor wing aircraft when they are used on wildfires. Theoretically this would better justify the hundreds of millions of dollars spent by the Forest Service on firefighting aircraft. In FY 2017 for example, the agency spent over half a billion dollars on fire aviation; $507,000,000. If completed and the results implemented, the study could make it possible to answer the question: “What are the best mixes of aircraft to do any fire suppression job?” Data collected from this study and other sources would be used to inform decisions about the composition of the interagency wildland firefighting aircraft fleet — to use the best, most efficient tools for the job.
Last year one person familiar with the issue told me that they thought the actual, accurate data from the AFUE would never be released — like the situation with the RAND air tanker study that the Forest Service never released even after our Freedom of Information Act request. Two years after it was completed RAND released the document.
Above: Tanker 912, a DC-10, drops on the Lolo Peak Fire near Florence, Montana south of Missoula. Photo by John Ames.
(Originally published at 9:39 a.m. MT March 4, 2018)
Every year the National Interagency Fire Center compiles a Wildland Fire Summary and Statistics Report. It usually runs about 70 pages and has piles of data about fire occurrence, weather, and the resources deployed. Since the number of large air tankers on exclusive use contracts has varied from 44 to 9 since 2002, (and 13 this year) an obvious question is, how many do we need? The number of Type 1 helicopters was cut in 2017 from 34 to 28, and that reduction will remain in effect this year.
These numbers do not count aircraft on call when needed (CWN) contracts — aircraft that may or may not be available when the call goes out. Since CWN vendors earn no money unless they are activated, the companies have to charge more to stay afloat. In 2017 the average daily rate for large federal call when needed air tankers was 54 percent higher than aircraft on exclusive use contracts. The hourly rate was 18 percent higher.
I have been discussing the data in the annual reports with one of our frequent contributors, Bean Barrett, who has taken the data analysis to a different level. Some of the key information includes aircraft requests, unable to fill (UTF) rates, and fire occurrence. We both agree that UTF information is imperfect. It is very possible that if an Incident Commander or Dispatcher knows that no air tankers or helicopters are available, they may not waste time sending in a request. Tracking these historical non-requests at this time is impossible.
And, aircraft don’t put out fires. In ideal conditions they can slow it down enough to allow firefighters on the ground to move in and actually put it out — or at least stop the spread on a section of the fire.
With those caveats, check out the work below that Bean has done, crunching the numbers in the annual fire reports. On his graph legends, “T1-2” refers to Types 1 and 2 fixed wing air tankers. If there is an “H”, it is about helicopters. Type 1’s are larger than Type 2’s.
By Bean Barrett
Maybe there is a story in the data after all as far as air tankers go. All derived from NIFC data. Not exactly ops research but perhaps useful for some insight. Like all data, this was probably measured with a micrometer, marked with a felt tip pen, and cut with an axe. So don’t take this one to the bank.
Aircraft requests and fires larger than 40,000 acres
I didn’t draw in the trend line on the fires above but the number of fires >40K acres is clearly increasing [red line]. The number of fires are on the right axis in red and the number of tanker requests by type are on the left axis.
Judging from the number of requests, the response to the increasing trend in large fires has been an increasing number of requests for T1/T2 air tankers [purple line]. Seems obvious.
What isn’t obvious is why the nearly straight line increase in fixed wing requests. Is there some kind of learning curve going on that has resulted in a steady increase in the perceived or actual value of T1-2 fixed wing air tankers? This nearly constant rate of increase in demand needs explaining and nothing in the NIFC data helps.
The requests for helos remained flat. What is curious is that there is little difference between Type 1 Helos and Type 2 helos. You would think that there would be a larger increase in requests for Type 1 helos when there is an increase in the number of big fires.
Aircraft requests and the number of significant fires
This slide looks at the number of requests and the number of NIFC significant fires. Significant fires are defined as >100 acres in timber or >300 acres in grass. The number of significant fires is on the right axis in red and the number of tanker requests by type are on the left axis.
I looked at significant fires because you would think that by the time a fire got to 100 acres / 300 acres someone would be thinking about air tanker IA support. Not much of a trend in the number of significant fires.
If anything, there has been a slight decrease in helo requests over the last three years while there has been a big increase in the number of significant fires. Why doesn’t the demand for helo support follow the number of significant fires? Aren’t helos used for IA? Are the majority of helo requests not related to suppression? Why isn’t the demand for helo support reflected in the number of fires?
Not much correlation between fixed wing requests and the number of significant fires pre 2014. Better in the last 3 years. Maybe fixed wing has been more involved in IA? However, the next slide changed my mind.
Significant fires exceeding 40,000 acres and air tanker UTF rate
Since there was no NIFC data on early suppression success rates when compared to tanker availability, I made an assumption for this and the next slide. I divided the number of fires > 40K acres by the number of significant fires and assumed that percentage roughly represented the significant fires that were not successfully suppressed before they could grow >40K acres. Percentage of significant fires that grew to >40K acres is on the right axis and the UTF % for T1/2 tankers is the left axis.
Up to 2014 it looks like fixed wing T1/2 UTF rates were correlated with the percentage of fires that grew >40K acres. [High UTF rates meant more significant fires grew >40K acres].
However, UTF rates went down for the last 3 years and were unrelated to the number of significant fires that grew >40K acres. Fixed wing availability didn’t correlate well with suppression efforts that kept significant fires from growing >40K acres. Perhaps the majority of fixed wing requests are not for suppressing significant fires.
Significant fires exceeding 40,000 acres and helicopter UTF rate
This slide might be the most important one provided someone can sort out the difference between correlation and causation. The red line is the percentage of significant fires that grew>40K acres [right axis]. The UTF rate for helo types is on the left axis.
Interpretation 1. Helo availability is THE key to more effective early suppression and preventing significant fires from turning into large costly fires. When helo UTF rates were below 20%, significant fires that grew >40K acres were at or below 1.5%. If this is indeed a causal relationship, contract for a much larger helo fleet for IA and the huge wildfire suppression bills will come down considerably.
Interpretation 2. Helos aren’t requested until a significant fire becomes unmanageable and then a large number of requests saturate the system resulting in a high UTF rate. I tend to discount this interpretation because [see # Requests and Significant Fires above] total request numbers don’t go up when the number of fires go up. They don’t. Only the UTF changes. This would indicate an overall helo inventory shortfall.
Either way, there simply aren’t enough helos when they are needed. If the number of helos under contract was closer to a reasonable objective, UTF rates would not have the peaks shown above.
Above: N137BH, a Sikorsky 70A or “Firehawk” helicopter, flies to refill its water bucket after dropping on the Rankin Fire in South Dakota September 13, 2017. Photo by Bill Gabbert.
(Originally published at 5:34 p.m. MT February 8, 2018)
The stats are in for the use of firefighting helicopters in 2017. The number of requests for Type 1 helicopters was close to average, but the number of orders that were Unable To be Filled (UTF) was almost double the number of filled orders. In 2017 60 percent of the requests were not filled — 220 of the 370 that were needed. That is by far the highest percentage of UTFs in the last 18 years. The second highest was 46 percent in 2012.
Type 1 helicopters are the largest used on fires, carrying 700 to 2,800 gallons.
One important change in 2017 was the 18 percent reduction in the number of Type 1 helicopters on exclusive use (EU) contract. For several years the U.S. Forest Service had contracted for 34 EU Type 1 ships, but reduced that to 28 in 2017.
These contracts require continuous availability throughout the mandatory availability period, which can be 180 days or more. Other helicopters may or may not be procured on a Call When Needed (CWN) contract. A CWN aircraft could be tied up on something else or undergoing heavy maintenance when the phone in the office rings asking if they can respond to a fire. And CWN aircraft cost the government much more to operate than EU resources.
These large helicopters are beloved by wildland firefighters, since they can strategically drop with pinpoint accuracy thousands of gallons of water or retardant while working close air support with ground personnel. This can cool and slow the spread of the fire, enabling crews to work nearer the fire edge. A series of water drops can enable hand crews to make steady progress on active flanks of the fire. Helicopters can often refill with water from a nearby lake or tank, making 5 to 15 minute turnarounds. A fixed wing air tanker that has to refill at an airport takes much longer.
The six helicopters that were cut last year:
Prineville, Oregon (BK-1200) Swanson Group Aviation
Helena, Montana (BK-1200) Central Helicopters
Hamilton, Montana (BV-107) Columbia Helicopters
Custer, South Dakota (BV-107) Columbia Helicopters
Lancaster, California (CH-54A) Siller Helicopters
Minden, Nevada (CH-54A) Helicopter Transport Services
Type 1 helicopters are frequently moved around depending on fire danger and incident activity and are often not at their home base.
At this time, the agency has determined 28 to be the appropriate number of Type 1 helicopters on EU contracts given current types and numbers of other aircraft in the fleet. This is in line with the 2012 Airtanker Modernization Strategy.
She said “Up to 30 additional Type 1 helicopters” are on Call When Needed contracts, which includes the six that no longer have EU contracts.
The Airtanker Modernization Strategydoes not make an independent recommendation on the number of helicopters or air tankers that are needed. But it refers to a study conducted from 2007 to 2009, the NIAC Interagency Aviation Strategy, which concluded that the optimum number of Type 1 helicopters on EU was 34. It also recommended a total of 35 air tankers by 2018, which included three water-scooping air tankers. At the beginning of the 2017 western fire season there were 20 large and very large air tankers on EU contracts plus two water-scooping air tankers.
Table from the “2007-2009 NIAC Interagency Aviation Strategy document. Phase III”, page 21.
Our opinion
As this is being written, the politicians we elect to represent us in Washington are trying to put together a last minute (literally) federal budget that will keep the government from shutting down again tonight. They are proposing to increase the dollars spent on Defense by $165 billion. This would raise the total military budget for the next two years to $1.4 trillion. (A source in D.C. told us there is a chance the legislation will include a fix to the fire borrowing fiasco, where funds are taken from other functions to pay for wildfire suppression.)
Everyone agrees that the military needs to be adequately funded, but in 2016 the amount the U.S. spent on defense was almost equal to what the next 14 countries combined spent.
On Tuesday, the International Institute for Strategic Studies released its Military Balance 2016 report, which seeks to examine closely the changing nature of military power. On a grand scale, the report showed – yet again – that U.S. military spending easily dwarfed the rest of the world. With a defense budget of around $597 billion, it was almost as much as the next 14 countries put together and far larger than the rest of the world.
Military spending, U.S and the rest of the world. Washington Post.
Much of the defense budget is spent in countries on the other side of the world. Meanwhile, the defense of our Homeland gets cut. Last year we saw 18 percent fewer Type 1 helicopters and the number of large air tankers was 57 percent of the recommendation in the NIAC Interagency Aviation Strategy.
Our suggestion is to prioritize the defense and protection of our citizens, homeland, forests, parks, grasslands, refuges, prairies, and wildlands FIRST, before considering spending trillions on the other side of the world.
In 2016 there was an increase in the percentage of requests for large air tankers that went unfilled, increasing from 10 percent in 2015 which was the lowest since 2009, to 13.4 percent in 2016.
Counting the U.S. Forest Service HC-130H air tanker there was a maximum of 21 large and very large air tankers on exclusive use contracts in 2016. However, the two Erickson MD-87 aircraft were not available for most of the year due to problems with the retardant system. The company claims they have fixed the issue and they should be ready to go this summer. A few other call when needed (CWN) large and very large air tankers were activated for weeks at a time in 2016. Unless new contracts for CWN air tankers are issued that will be effective this year, the number of available air tankers in 2017 should be about the same. A new exclusive use contract is expected to be in effect in 2018.
Tanker 12 on the Trailhead Fire. A Cobra helicopter is in the background. Photo July 1, 2016 by Matthew Rhodes.
The number of acres burned in the lower 49 states (which excludes Alaska) was virtually the same in 2015 and 2016, with both being pretty close to average. There were also few extended fire sieges involving multiple large fires occurring at the same time that required a high number of air tankers. Having the fires spread out over time minimizes the number of air tanker requests that go unfilled.
The number of acres burned in wildfires in the lower 49 states (excludes Alaska).
Here are some of the Unable to Fill numbers we computed from the data reported by the National Interagency Fire Center for 2016:
Type 1 and 2 large air tankers: 13.4%
Single Engine Air Tankers: 21.1%
Type 1 helicopters: 12.3%
Type 2 helicopters: 8.6%
Type 3 helicopters: 8.3%
There were only seven requests for MAFFS air tankers, and all were filled.
Coulson’s Air Tanker 131 being pushed out of the hangar at McClellan Air Force Base in Sacramento, March 21, 2014. Photo by Bill Gabbert.
Today two newspapers published lengthy and detailed articles about the shortage of large air tankers. The Missoulian’s has an emphasis on their home-town company, Neptune Aviation, while the Arizona Republic’s has several references to last year’s Yarnell Hill Fire in Arizona that killed 19 members of the Granite Mountain Hotshot crew. You will recognize the names of one or two of the people quoted in the articles.
Below are the introductory paragraphs:
Missoulian:
Wildfire season officially begins April 28, and the U.S. Forest Service is heading into it with only three modern firefighting air tankers.
Missoula-based Neptune Aviation has one of those planes on contract. It argues to have two more, but competitors won a protest over Neptune’s no-competition award worth almost half a billion dollars over 10 years. By August, Neptune will have two more jets looking for work.
“We’re still cranking out air tankers,” Neptune CEO Ron Hooper said Friday. “But that’s the state of limbo we’re in. We’re waiting to see what the Forest Service will do.”
Meanwhile, one of Neptune’s six Korean War-vintage P2-V bombers saw seven hours of flying time on a wildfire in New Mexico last week. Of the five companies that received Forest Service “next-generation” contracts to provide seven new fire bombers last year, three have failed to deliver their planes.
Arizona Republic:
National wildfire officials are urgently trying to reinforce an undersized and aged fleet of retardant-dropping air tankers in the aftermath of June’s deadly Yarnell Hill Fire, but as they gird themselves for a potentially treacherous 2014 season, significant improvements may be more than a year away.
Tom Harbour, national director of fire and aviation management for the U.S. Forest Service, said drought conditions have dried up the West since last summer, when monsoon rains spawned a bumper crop of fire fuels.
“You bet we’re concerned and worried about what’s going to happen,” Harbour told The Arizona Republic. “This puts us in a precarious position as we head into this new season.”
Harbour noted that numerous unusual winter wildfires already have erupted and been doused in Arizona’s Tonto National Forest and in drought-ravaged Southern California. State officials said on April 2 that 179 wildland fires already had been reported this year in Arizona alone.
The significance: “We could be off to a very early start,” said Harbour.
The Arizona Republic and USA Today are both credited with this video report, uploaded Saturday to YouTube, about air tanker shortages:
Air tankers available in 2014
The following Type 1 & 2 air tankers, commonly called “large” air tankers, will be available on exclusive use contracts this year:
8 — on the “legacy” contract, (1 Minden P2V, 6 Neptune P2Vs, and one Neptune BAe-146)
2 — on the “next-gen” contract (1 Coulson C-130H and a 10 Tanker DC-10)
Possible: 5 other next-gen aircraft that received contracts on May 6, 2013 that may or may not become certified. The companies that still have not supplied the aircraft are Minden, Aero Air, and Aero-Flite.
Total: between 10 and 15. This does not include the two Neptune air tankers that were issued the sole source contract. That contract was protested, and the protest was upheld by the Government Accountability Office. The U.S. Forest Service can also call upon up to eight MAFFS military C-130 aircraft and can borrow some old CV-580s from Canada and Alaska if they are available. One additional DC-10 is on a call when needed contract and may be available if needed by the U.S. firefighting agencies.
Requests for air tankers that were unable to be filled
We have read several references recently about the number of requests for air tankers by wildfire incident commanders that were unable to be filled (UTF). We have been reporting on this issue for several years and updating it annually, but just to be sure the latest data is out there, below, again, is a graphic we put together from National Interagency Fire Center reports. The UTF numbers do not include the requests that were canceled, contrary to what you may have read elsewhere.
New data that the National Interagency Fire Center released about the 2012 wildfire season reveals that almost half, or 48 percent, of the requests for large air tankers could not be filled. Of the 914 requests, 438 were rejected as “unable to fill” (UTF), meaning no air tankers were available to respond to the fire; 67 were cancelled for various reasons. The requests that were filled included 346 for civilian contracted air tankers and 63 for military Modular Airborne FireFighting Systems (MAFFS) C-130s.
For additional perspective, consider that the number of requests for air tankers during the 2000 fire season was higher than the 13-year average between 2000 and 2012 — 548 requests vs. the average of 434, but in 2000 only 7 percent of them were UTF. In 2000 there were 40 large air tankers on exclusive use contracts compared to between 9 and 11 in 2012.
More acres burned in the United States in 2012 than average. At 9.3 million, it was the most since 2007. But the number of fires was surprisingly small, only 67,774 which is the lowest number since 2005.
The average number of fires in the lower 49 states each year is gradually decreasing, but the average size is increasing rapidly. This could be due to a number of factors, including climate, increased fuel loading (vegetation), reduced budgets, fewer firefighters, and not as many air tankers.
One of the reasons the U.S. Forest Service has allowed the air tanker fleet to atrophy may be a misguided attempt to save money. Fast, aggressive, initial attack on new fires can reduce the number of megafires that may burn hundreds of homes while costing the taxpayers tens of millions of dollars in suppression costs alone. The 2002 Federal Aerial Firefighting Report, usually known as the “Blue Ribbon Panel Report”, addressed this issue:
While cost-saving is an essential contracting criterion, it appears to have displaced other, less-quantifiable criteria that call for more judgment and experience, such as value, safety records, and past performance. Pilots have sarcastically referred to this cost-focus philosophy as “budget protection” rather than “fire protection.” In contrast, a Canadian philosophy states, “We can’t spend too much the first day [of a fire],” seems to justify spending money on early containment of a fire, and doing so in an operationally effective way that minimizes the number of escaped fires. In the long run, the Canadians believe that they spend far less for a quick-response capability designed to contain small fires than they do to fight fires after they grow large.
It has has been 1 year, 2 months, and 24 days since the U.S. Forest Service issued a solicitation for next-generation large air tankers, but no contracts have been awarded.
This slide might be the most important one provided someone can sort out the difference between correlation and causation. The red line is the percentage of significant fires that grew>40K acres [right axis]. The UTF rate for helo types is on the left axis.
