Results released for study of water enhancers used by firefighting aircraft

Five products were evaluated during a three-year period

CoE water enhancer study fire

Results have been released for a three-year study on the use and effectiveness of water enhancing products for Single Engine Air Tankers (SEATs). It was conducted by Colorado’s Center of Excellence (CoE) for Advanced Technology Aerial Firefighting, and the Bureau of Land Management from 2017 through 2019. It is titled, “Aerial Firefighting Field Operational Evaluation of Water Enhancers; Results and Recommendations.”

In addition to long term fire retardant (LTR) which is usually used in large and very large air tankers, other water enhancing products are often used by SEATs and sometimes helicopters, and occasionally by large air tankers. For example the air tankers from North America that worked in Chile in recent years used products other than LTR. The enhancers are also used in Australia in addition to LTR. SEATs often use retardant but some bases have switched to other products.

Data was collected for the study through 95 evaluations of the performance of the water enhancers by aerial supervision personnel, pilots, ground firefighters, a mixer-loader, and by two dedicated field observers hired for that purpose during the final year of the project.

The CoE evaluated the following water enhancers:

  • GelTech Solutions FireIce 561® (uncolored)
  • FireIce HVO-F® (orange colorant)
  • FireIce HVB-Fx®
  • G5 BioSolutions BlazeTamer 380®
  • Thermo Technologies Thermo-Gel 200®

(In the interest of full disclosure BlazeTamer is a supporter of Fire Aviation.)

The full 63-page report can be downloaded. Here are some of the recommendations:


Increase the Use of Water Enhancers (Especially During Initial Attack)

Aircraft are used in a variety of wildfire management roles in many parts of the world. They can be used to deliver suppressants to sections of the fire edge that are difficult to access on the ground and can reduce the intensity and spread rates to allow ground crews to work along the fire edge. This is critical during the initial attack of wildfires in remote locations.

When used properly, specifically in direct attack on the fire with ground resources present, the CoE’s data showed that there is a favorable reduction in flame heights with the use of water enhancers as opposed to LTR, especially in light fuels. Observers shared a number of comments that suggest that they are quite effective at reducing fire behavior.

  • Water enhancers are much more effective when used in direct attack than water or foam and much less expensive than retardant.
  • The choice of tactics may also depend on the availability of suitable aircraft, payload, and airbase facilities for each option.
  • Water and foam all dry at a faster rate than do water enhancers; however, ground follow-up is critical to the success of a water enhancer line “holding.” This is even more important on hot and windy days when spread rates and the probability of ignition are both high, as holding times under these conditions will be 30 minutes or less.
  • Holding time was difficult to quantify because many of the drops were not observed at all or did not last long enough to capture data.
  • The CoE’s study showed that holding times for the products that were evaluated range from 20 minutes to 2 hours. Because the water enhancers are only effective as long as they retain water, fire managers must realize that the use of these products should be limited to direct attack applications.

Consider Use of Water Enhancers in Helicopters

Use of water enhancers in helicopters should also be considered on large fires to directly support crews in controlling hot spots and reducing the amount of time required to control critical sections of fireline.

Some additional benefits of water enhancer use in helicopters may include:

  • Fireline production per drop when using water enhancers is increased significantly due to the creation of a dense, narrow drop pattern versus the pattern created when dropping untreated water.
  • Retardant is expensive and inefficient when used for direct attack.  Retardant increases the weight of water from 8.3 lb per gallon to about 9.1 lb per gallon.
  • Only 85% of retardant (i.e., the water content) is effective when used for direct attack; 15% is the chemicals and coloring agent used for indirect attack.
  • Retardant is more expensive. For example, BlazeTamer 380 costs $0.83 per gallon as compared to $2.50 per gallon for Phos Chek 259-F LTR.
  • Ease of set-up and breakdown of water enhancer mixing systems as compared to mobile retardant bases allows for fast movement around a fire rather than having to stay in one location. No heavy equipment is needed.

Use Water Enhancers with Prompt Ground Resource Follow-Up

When enhancers are used properly for direct attack and the number of aircraft is sufficient, they may be capable of fully extinguishing the fire with little to no ground support. The CoE recommends water enhancer use for situations where follow-up from the ground can be provided promptly (typically within 1 hour).

For an extended attack incident, particularly when the ground support is several hours away and the need is to hold or slow the spread until they can catch up, retardant is likely the best tool. There were numerous observations made during this study in which the enhancers were very effective when supported by ground resources. Ground crews play an essential role during fire suppression, with water enhancer technology offering a method to increase their suppression capacity. Aerial suppression provides a temporary holding role, rather than extinguishing fires. Follow-up by ground crews before the water enhancers dry out or fire burns through the drop zone is essential.

In 2018, the CoE received observations from several initial attack fires with high rates of spread and intensity where ground resources were delayed in supporting the drops in a timely manner, resulting in drops being burned around or spotted over.


There were other recommendations about training, using an aircraft with an electro-optical/infrared sensor to evaluate the effectiveness of the drop, and processes to ensure quality control of the water enhancer mixture.

Ontario Air Tanker Base was closed after a jettisoned load of retardant landed on homes and children

Air tanker history from 1977

Ontario Airport C-119 jettisoned fire retardant air Tanker 135
Air Tanker 135, a C-119, jettisoning 2,000 gallons of fire retardant west of the Ontario Airport, July 29, 1977. Photo by J.D. Davis.

When Air Tanker 135 took off from Ontario Airport east of Los Angeles at 5:30 p.m. July 29, 1977 the Mine Fire 16 miles to the south was threatening homes and burning thousands of acres of 60-year old brush in Tin Mine and Hagador Canyons on the southwest edge of Corona.

In a New York Times article about the fire, Corona was described as “a rural town”, and:

A force of 900 firefighters made a successful stand in front of the Village Grove development as flames from the 2,000‐acre blaze came within a football field of homes with price tags of up to $150,000.

Rose Bello was standing outside her house half a mile from the end of the runway at the northwest corner of Belmont Street and Mildred Avenue watching her three-year-old daughter Julie riding a bicycle with a friend. She saw the tanker flying very low, just clearing some power lines. When it passed over her home fire retardant was pouring from the plane.

Ontario Airport C-119 jettisoned fire retardant map
Ontario Airport in an aerial photo taken in 1994 showing the approximate location of the jettisoned retardant. Google Earth.

“The noise was so loud it hurt my ears,” she told a reporter from the Daily Report. “I heard my little girl scream because [the retardant] was in her eyes and all over her clothes — she was just soaked.”

At the time the FAA required restricted air tankers like the C-119 to turn left off the Ontario runway to avoid the heavily populated center of the city. The aircraft had three engines. Two of them were props, Wright R-3350 Duplex-Cyclones, a twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders. After the C-119 retired from the military a third engine was added, a turbojet in a nacelle above the fuselage to supply additional power if needed on takeoff or while making a retardant drop.

The pilot, of course, didn’t plan to drop retardant from a very low level on four homes, six cars, children on bicycles, drying laundry, a corn field, and an assortment of trees and sheds. But shortly after take off one of the radial engines developed a runaway propeller, causing the engine to exceed the RPM limits. If not corrected immediately this can cause the propellers to fly off, possibly causing severe damage to the aircraft. When this occurs the pilot will usually reduce the power to the engine and shut off the fuel, a procedure that should prevent additional damage to the engine and the aircraft. But shutting down an engine, especially at low level while climbing and turning, may cause a stall. The pilot jettisoned the 2,000 gallons of retardant, about 9,000 pounds, to reduce the chances of a crash. The aircraft then gained enough altitude to turn and land safely back at the airport.

Ontario Airport C-119 jettisoned fire retardant air Tanker 133
Air Tanker 133, a C-119, making the required left turn after takeoff at the Ontario Airport, July 28, 1977. Photo by J.D. Davis.

J.D. Davis, who took these two aircraft photos, was monitoring a scanner and heard the pilot ask to jettison the load on the runway, but the tower refused permission. The pilot headed toward a corn field near Ms. Bello’s home. That is where most of the retardant landed, plowing up several rows of corn, but part of the load was a little short.

Jim Stumpf was the Deputy Fire Management Officer and Aviation Officer for the nearby Angeles National Forest, the agency that ran the air tanker base at the airport. I asked him what he remembers about the incident:

When I arrived after about 40 minutes (traffic) everyone was really unhappy. CDF [California Department of Forestry] was on scene working clean up and I requested (Lower San Engine I think) to come to the incident to assist in the cleanup. A CDF Batt. Chief and I were directing the clean up and talking with a great deal of the affected residents assuring them that there were no long term effects from the retardant. It would wash off of adults, children, houses, etc. The clothes on the line could be rewashed without any problem.

If I remember, we spent several hours at the scene — CDF and I bought cokes and pizza for our respective crews. The local residents started consuming copious amounts of beer, wine and whiskey so it ended as a block party for all concerned. CDF and USFS turned down the offer to participate in the party. It started out bad and ended up a party. After our street and house cleaning all equipment was returned to their respective stations.

The following day I took Charity Burton to the scene (she was handling claims for the ANF). We talked to as many residents as possible and told them about the claims process. The best I can remember we didn’t get any claims. I drove through the neighborhood a few times on periodic visits to the tanker base, and even talked to some folks who thanked us for being responsive. All was well but they didn’t like tankers flying over their house.

Before the incident 70 individuals and two churches had filed two lawsuits totaling $11.70 million for damage due to noise from jets taking off from the airport, according to an article written in 1977 by Richard Brooks of the San Bernardino Sun.

Back then there were more air tankers than we have today, and they were not forced to move around the country as often following the latest hot, dry, and windy weather. The tanker crews that had been permanently stationed at Ontario perfected the tricky left turn while climbing off the runway, but tanker pilots from other areas were not always as diligent avoiding heavily populated areas. For the rest of the 1977 fire season only the permanent tanker was allowed to use Ontario. After that the base was permanently closed.

Ontario was the southernmost base that could support and refill large air tankers, so closing it reduced their ability to quickly and aggressively respond to fires in Los Angeles, Riverside, and San Diego Counties.

Epilog

In 1987 a C-119 (N48076) with the same tanker number, 135,  crashed while working the Whalen Fire on the Shasta-Trinity National Forest. Killed were Hawkins & Powers pilots Bill Berg and Charles Peterson, and mechanic Stephen Harrell. The crash was result of an inflight failure, with the right wing, the left wing tip, and the tail boom separating from the aircraft during a retardant run.

A big thank you goes out to J.D. Davis who supplied information about the incident and the C-119 photos.

Why 2,500 liters of retardant was dropped in Australia’s capital city

It happened near the National Emergency Services Memorial

Retardant drop in Canberra, ACT
Retardant drop Feb. 4, 2020 in Canberra, ACT, Australia. Photo by ABC News Tamara Penniket.

Wednesday’s accidental drop of 2,500 liters (660 gallons) of fire retardant in downtown Canberra, Australia led to a hazardous material response from the Australian Capital Territory Fire & Rescue.

Richard Alder, the General Manager of the National Aerial Firefighting Centre in Australia, said the inadvertent retardant drop came from a Single Engine Air Tanker, an Air Tractor AT802 with a Gen3 door. The SEAT encountered significant turbulence on climb-out from the retardant base at Canberra airport on the way to the Orroral Valley Fire.

Retardant drop in Canberra, ACT
Retardant drop Feb. 4, 2020 in Canberra, ACT, Australia. Screenshot from ABC News video.

“In maneuvering the aircraft through the turbulence, the pilot accidentally activated the drop button,” Mr. Alder said. “The drop system was armed, in accordance with normal climb-out procedure, to enable a rapid emergency drop [should it become necessary].”

He said the aircraft operator is reviewing their procedures to see if the risk of an inadvertent drop can be reduced, while maintaining appropriate safety for the aircraft and pilot.

The retardant affected Parkes Way, a parking lot at Rond Terrace, a large roundabout with a pond, and the south end of Anzac Parade, the street that leads to the Australian War Memorial. The drop was a short distance northwest of the National Emergency Services Memorial and about a mile north of the Parliament House at the capital.

Retardant drop in Canberra, ACT
Retardant drop Feb. 4, 2020 in Canberra, ACT, Australia. Photo by ABC News Elise Fantin.

Mr. Alder said the SEAT was following a route to the fire that avoided overflight of residential areas.

Several decades ago in the United States large air tankers worked out of a retardant base at the Ontario Airport east of Los Angeles. The story goes that a lady who lived near the airport was known for complaining about the noise from the firefighting aircraft. Her criticism had little effect until the day one of the tankers had a problem on climb-out and had to jettison the load. And, as luck would have it, the retardant landed on that poor lady’s house. Not long after that the tanker base was permanently closed.

Air tanker drops retardant in downtown Canberra, Australia

About a mile from Parliament House at the capital

Retardant drop in Canberra, ACT
Retardant drop Feb. 4, 2020 in Canberra, ACT, Australia. Photo by ACT Emergency Services Agency.

An air tanker dropped retardant in the city of Canberra, the capital of Australia on February 4.

The aircraft was working on the Orroral Valley fire in Namadgi National Park in the Australian Capital Territory (ACT). The ACT Emergency Services Agency said the aircraft “encountered turbulence causing 2,500 litres of retardant to be released on Parkes Way.” A number of cars were coated with the retardant, and judging from the photo below, at least one person.

Retardant drop in Canberra, ACT
From this retardant shadow it appears that at least one person was affected by the retardant drop in downtown Canberra, ACT, Australia February 4, 2020. Photo by Lukas Coch, AAP.

The fact that 2,500 liters (600 gallons) were released leads one to guess the aircraft may have been a Single Engine Air Tanker, unless it was a partial load from a large air tanker.

The turbulence could have forced a low flying air tanker to suddenly and unexpectedly lose altitude, and the pilot might have jettisoned the load in order to help regain altitude and control. Or, the G-forces produced stress causing the tank doors or other hardware to fail. Regardless, we are happy that retardant was the only thing that fell out of the sky on Tuesday.

ACT Fire & Rescue worked with the Environmental Protection Authority to assess the situation at the impacted area which included the carpark at Rond Terrace and Anzac Parade at Rond Pond.

The retardant was close to the National Emergency Services Memorial and about a mile north of the Parliament House at the capital.

(UPDATE, Feb. 10, 2020: More information has become available about the cause of the retardant drop)

Scientists develop retardant gel with “persistent retention”qualities

It could be used to pretreat areas at high risk of fire ignitions to make them fire resistant

long term gel fire resistant
Overhead time-course images of 3 m × 3 m unmowed (standing) grass plots that were untreated or treated with different coverage levels, dried, weathered, and allowed to dry again over time in the environment prior to burning. The normalized area burned over time demonstrates that CL2 (coverage level 2, or 2 gallons per 100 square feet) is sufficient to preclude spreading of the fire. Air tankers use the same unit of measurement, coverage level, to specify how much retardant will be dropped. Figure from the research.

(This article first appeared on Wildfire Today.)

A group of scientists and engineers have developed a new fire retarding chemical, actually a gel in this case, that they say can be effective for months after being applied to vegetation.

The millions of gallons of red fire retardant that air tankers drop every year is usually made from ammonium phosphate or its derivatives. It has  been called “long term fire retardant” because even after it dries, the chemical can interfere with the combustion process and may still retard the spread of  a vegetation fire to a limited degree. However research and experience in the field has shown some formulations can be toxic to fish.

Gels have been used by firefighters for several decades on structure fires occasionally on vegetation fires. The products can be more effective than plain water due to their ability to stick to a vertical surface or vegetation. Water can remain in the gel for an hour or more depending on the ambient temperature, wind, and humidity. GelTech Solutions recently received a contract from the Oregon Department of Forestry to supply a blue-colored version of FireIce HVB-Fx gel to be used in air tankers. The company says the product passed the U.S. Forest Service’s newly revised, more challenging requirements for wildland fire chemicals. But the safety data sheet for the product says, “Titanium dioxide [a component of the product] has been classified by IARC as a possible carcinogen to humans (Group 2B) through inhalation of particulate dust.” The safety data sheet goes on to say, “This classification is based on inadequate evidence for carcinogenicity in humans, but sufficient evidence of carcinogenicity in animals (rats). It should be noted that recent studies have demonstrated that the rat may be particularly sensitive to high levels of toxicity dusts such as titanium dioxide. Epidemiology studies do not suggest an increased risk of cancer in humans from occupational exposure to titanium dioxide. The conclusions of several epidemiology studies on more than 20,000 TiO2 industry workers in Europe and the USA did not suggest a carcinogenic effect of TiO2 dust on the human lung.”

This is not the first time blue gel has been used in air tankers. The photo below was taken in the Black Hills of South Dakota August 15, 2006.

blue gel air tanker fire retardant
A single engine air tanker drops blue gel on a fire near Shep’s Canyon in the Black Hills of South Dakota August 15, 2006. Photo by Bill Gabbert.

The scientists who developed the new fire retarding gel that they claim has “persistent retention”qualities said their formulation is environmentally benign, nontoxic, and will “biodegrade at desired timescales.” After application, it will retain its ability to prevent fires throughout the peak fire season, even after weathering that would sweep away conventional fire retardants. The cellulose-based gel-like fluid stays on target vegetation through wind, rain and other environmental exposure, they said.

“This has the potential to make wildland firefighting much more proactive, rather than reactive,” said Eric Appel, the study’s senior author and an assistant professor of materials science and engineering.

Treating wildfire prone areas prophylactically could provide a highly targeted approach to wildfire prevention, but, until now, long-lasting materials have not been available.

The researchers have worked with the California Department of Forestry and Fire Protection (CAL FIRE) to test the retardant materials on grass and chamise — two vegetation types where fire frequently starts. They found the treatment provides complete fire protection even after half an inch of rainfall. Under the same conditions, a typical commercial retardant formulation provides little or no fire protection. The researchers are now working with the California Department of Transportation and CAL FIRE to test the material on high-risk roadside areas that are the origin of dozens of wildfires every year.

“We don’t have a tool that’s comparable to this,” said Alan Peters, a CAL FIRE division chief in San Luis Obispo who monitored some of the test burns. “It has the potential to definitely reduce the number of fires.”

The Stanford-developed treatment contains only nontoxic materials widely used in food, drug, cosmetic and agricultural products, according to the developers. The unique properties of these gel-like retardant fluids allow them to be applied using standard agricultural spraying equipment or from aircraft. It washes away slowly, providing the ability to protect treated areas against fire for months as the materials slowly degrade.

Link to the research paper, “Wildfire prevention through prophylactic treatment of high-risk landscapes using viscoelastic retardant fluids”.

Thanks and a tip of the hat go out to Tim, Carl, and Kelly. Typos or errors, report them HERE.

Tanker 116 sees action at Phoenix

Air Tanker 116 HC-130H retardant

Above: Air Tanker 116, an HC-130H, sprays retardant on a fire near Phoenix, June 22, 2017. Fox 20 Phoenix.

Tanker 116 saw some action today, dropping on a fire near Phoenix that closed Interstate 17. Fox 10 got a pretty fair shot of the drop, but unfortunately the camera operator, perhaps not experienced in covering air tankers, followed the aircraft very closely all the way through the drop so it was difficult to tell which of the two parallel retardant drops was made by T-116. Yes, there were two drops parallel to each other. One looked like it was very wide but the coverage on the ground was very thin. The other was much more narrow and and had better coverage.

The video below shows the drop, and I found it at 2:40:45, but when I first saw it, it was at a different time stamp. The video should begin a few seconds before that point, but it you don’t see it there, check a couple of minutes on each side.

The image below shows the two parallel drops. It is difficult to tell from the video which one was made by the HC-130H.

retardant drops
The two parallel drops can be seen at the lower-right. Screen grab from the Fox 10 video.
The news people in the audio have some problems with aircraft ID in that video and at another spot in the same video. At about 2:22:15, there is a second drop and you will hear the news people identifying a lead plane as a Single Engine Air Tanker and what is either an RJ85 or a BAe-146 as a DC-10.

About 2 to 3 minutes after that second drop, a third drop (at 2:25:45) is similar to the second one, and is possibly the same but from a different angle. I am fairly certain this third drop is an RJ85, since you can see the pregnant bulge on the belly.

The very lengthy video goes back to a fire near Los Angeles several times. The image below, a screenshot, show a retardant drop that affected several homes.

retardant drop houses Los Angeles
Retardant gets dropped on homes at fire near Los Angeles. Fox 20 Phoenix.
T-116 is using, not a conventional gravity retardant tank, but a pressurized Modular Airborne FireFighting System rig that is normally only used in military aircraft that have been temporarily drafted into an air tanker role by loading a MAFFS unit in the cargo hold. The compressed air that blows the retardant out of the 3,000-gallon tank sprays it out of a nozzle, breaking the thickened retardant into very small droplets. T-116 and six other HC-130H’s are in the process of being transferred from the Coast Guard to the U.S. Forest Service. If the process is complete by the end of this decade as the agency expects, all seven will have conventional gravity-powered retardant delivery systems and will be operated and maintained by contractors, but owned by the USFS.

Thanks and a tip of the hat go out to Tom and Brian.
Typos or errors, report them HERE.

Colorado studying SEAT-dropped water enhancer effectiveness during 2017 wildfire season

State-contracted SEAT T-831 drops sunset orange FireIce HVO-F®. Courtesy photo.

Above: State-contracted SEAT T-831 drops sunset orange FireIce HVO-F®. Courtesy photo.

Efforts are underway in Colorado to better evaluate how water enhancers delivered from a single engine air tanker can be more effective than retardants in fighting wildfires.

Colorado historically has only loaded long-term retardant into SEATs. These chemical concentrates are mixed with water and alter fuels so they do not support combustion. Retardant is dropped adjacent to — or ahead of — the fire to create a chemically induced fire break at its perimeter.

Molecular bonds from water enhancers, however, slow evaporation by creating a thermal protective coating. SEAT drops of water enhancers are mainly used in direct attack to slow or halt the fire’s rate of spread long enough for ground resources to access the fireline and mop up or supplement the knockdown process.

These gels have generally been limited in use in recent years, and field testing has been minimal. Information about water enhancers’ availability, use and effectiveness is sparse at best.

The study, lasting throughout the 2017 wildfire season in Colorado, has the following objectives, according to the Colorado Division of Fire Prevention and Control:  

  1. Observe and evaluate drops of water enhancers on wildfires and record information about 1) whether the water enhancer stopped or slowed the forward advance of the fire; 2)whether the water enhancer reduced fire intensity to a sufficient level for ground crews to manage the fire; and 3) whether the water enhancer persists on the surface fuels long enough to prevent hotspots from redeveloping or the fire from burning through the drop.
  2. Determine whether water enhancers delivered from a SEAT are effective on wildfires in Colorado. Effectiveness will be viewed in terms of how effective the products were in achieving the desired suppression objectives.
  3. Collect as much data as possible regarding the effectiveness of water enhancers used during initial attack and on emerging fires.
  4. Share lessons learned from the evaluations with interested parties, including cooperators and researchers.
  5. Test and evaluate newly developed ground-based mixing/batching equipment to assess the efficiency of the mixing and loading processes and the ability of the equipment to reduce response times.

“SEATs loaded with water enhancers will respond to fires on State and private land, as well as to fires under the jurisdiction of BLM, the National Park Service, and USFS. Mixing will be at the recommended ratios in the USFS Qualified Products List for each product on all drops. For the first load on each fire, State and Federally contracted SEATs will respond to the incident with water enhancer unless the ordering unit clearly specifies the need for LTR instead.

Decisions regarding where, when and how to apply a particular aerial retardant or suppressant are typically under the discretion of the Incident Commander, so if at any time the Incident Commander or the Air Tactical Group Supervisor feels that the enhancers are not performing as desired, the Incident Commander can immediately order that the SEATs be loaded with retardant.

The three water enhancers being evaluated in the study are: FireIce HVO-F, BlazeTamer 380, and Thermo-Gel 200L — each is approved by the U.S. Forest Service for use in SEATs.

The Center of Excellence for Advanced Technology Aerial Firefighting, with support from the Division of Fire Prevention and Control’s Aviation Unit and the Bureau of Land Management, is conducting the study.

After weighing input from researchers and firefighters, investigators will compile a preliminary and final report about the project’s findings.

Retardant used this year is a slightly different color

KCRA in Sacramento explores the color of fire retardant air tankers are dropping this year — it is a lighter shade of pink. The expectation is that after it is on the ground it will be easier for pilots to see, so that they can more easily tie on to previous drops, avoiding gaps in the retardant line.