Wildland firefighting: aerial ignition by helicopters using PSDs (ping pong balls)

 Helicopters have many uses in before, during and after wildland fires. One of the uses of helicopters is to drop small balls filled with compounds that ignite on the ground. These balls can be dropped to help with a prescribed fire as well as being dropped during a wildfire in remote areas to light a backfire. In the video below you will learn about these "ping pong balls" or PSDs are prepared and then dropped on the fire along with safety measures. I have not yet been able to find a video where you can see these PSDs being dropped on a fire. If I find one, I will amend this post.

 Direct link to video from PIO365 on YouTube

retardant v suppressant (follow-up)

Last week, I was writing about retardant v suppressant here. Let’s just say that I was wondering about when to use the term fire retardant and when to use the term fire suppressant. To be honest, I had forgotten that some of the information that I was looking for on retardant v suppressant is here in this blog, written over two years ago. What I am going to do is to spend a little time with what I wrote two years ago, and do some additional reading and revisit retardant v suppressant. However, I do want to briefly address the question that I raised last week.

In the meantime as I understand it, foams and gels (water enhancers) are suppressants, suppressing the fire. The Martin Mars, Canadair CL-215/415 (aka super scoopers) and some Helicopters with buckets and/or tanks (e.g. type 2 helicopters are among the aircraft using water/foam (usually clear). Retardant on the other hand (usually red in color) retards or slows the fire. Some of the aircrafts using retardant include but are not limited to CAL FIRE’s S-2T’s, P-2s and P-3s.

The US Forest Service has a page with some definitions that you might useful. In addition, you might want to read an article I posted in March 2009 on the differences between retardant and foam.

As I said, I’ll be writing more about retardants v suppressants, just not quite sure when. Tomorrow, I will be starting a series based on some time I spent last December watching the annual inspection of a Cessna 172 (aka a trainer).

on retardant and aerial firefighting

I saw a good article on inciweb last week about retardant and aerial fire fighting. It is called Retarding the Flames, and it is one of the news releases in conjunction with the Station Fire:

One of the most dramatic sights on a wildfire is the vision of an air tanker releasing its red payload of retardant near the fire. Behind this picturesque vision is a long history of science in the development of a valuable tool for firefighters - the use of fire retardant. Today retardant is used when appropriate to help suppress wildland fires.

Aerial drops of retardant have come a long way since the first recorded water drop in 1930, when a Ford Tri-Motor airplane used a wooden beer keg filled with water. Now air tankers can drop 500 to 2000 gallons of retardant at a time to help suppress fires. Helitankers, which are helicopters with built-in tanks, can drop up to 2000 gallons; retrofitted DC-10s have an 11,000 gallon capacity, and Boeing 747s 20,000 gallons.

Fire retardant is just one of many tools in the arsenal of firefighters. Like any other tool, it must be used under the right conditions and for the right job in order to be effective. Firefighters consider many factors in deciding which tools to use at a particular location and time to suppress a fire. Characteristics of the terrain, weather variables such as temperature, humidity, wind direction and force; the types of vegetation in the fire area; proximity to homes and other buildings; and the first priority of safety of the public and firefighters are all factors in choosing the right tools for the particular circumstances.

Retardant drops are most often used in extreme fire conditions. The retardant is usually dropped just ahead of the advancing edge of the fire and the flanks of the fire. This cools and so slows the fire, helping firefighters on the ground. It reduces the rate of spread and the intensity of fires, and slows larger, more damaging, and therefore can reduce the cost of fires. Often, using retardant to fight fires is the most effective and efficient method of assisting firefighters in protecting people, resources, private property and facilities. The remoteness of many wildland fires can delay the arrival of firefighting ground forces. Retardant drops can rapidly reduce the intensity and spread of the fire until firefighters can safely take action. Topography in the fire area and windy conditions are some of the factors limiting the effectiveness, and therefore the use, of retardant.  . . .

Go here to read the complete article

Tankers don't always carry full loads

I want to briefly mention something that I will spend more time writing about later after I have had a chance to do some research as well as talking to my aviator friends. That is, more often than not, tankers and helos will not carry a full load of retardant or water in their tanks due to aeronautical concerns. So, when the reports are saying that the Martin Mars can carry 7,200 gallons of water/gel mixture or that the Evergreen 747 supertanker can carry 20,500 gallons of retardant, they will carry these loads under "ideal" circumstances. The word "ideal" may be a misnomer, but it will have to suffice for now.

So, the Martin Mars was, as Bill Gabbert pointed out the other day, was carrying a smaller load of water (about 4,600 to 5,500 gallons). Chances are the Evergreen 747 supertanker was carrying a smaller load of retardant. Those of you who are aviators, or firefighters more familiar with aeronautics than I will know that one of the main reasons that tankers (and I assume helos) carry a lower load is because of something called density altitude. I will be writing some articles later about density altitude. I had begun discussions with some of my fire aviator friends several weeks ago about points such as density altitude and retardant coverage levels. I am beginning to revisit these issues.

One final point, while I am on the subject. When the Fox newscasters were covering the other day about the Evergreen 747 supertanker's retardant drops, one of them said that the supertanker could lay down a retardant line 3 miles long. This was also under "ideal" conditions and when the load is dropped in one run. I will add here that they were reading from specifications and other data on the supertanker, as they should. Having read specs myself, what I have to remember is to read words like "maximum" or the data sheet might say something like "the supertanker can drop a retardant line up to three miles long." Point being that I have to remember to think about these words as I listen to newscasts or read articles online.

Returning back to retardant line laid by the Evergreen 747 supertanker, the supertanker split the load into two runs, as all tankers are able to do. Likewise, at full capacity and under ideal conditions, the Martin Mars can cover 4 acres with its water/gel mix. If I understand things correctly, each water/gel load dropped by the Martin Mars covered less than 4 acres. Again, in later articles, I will try to write more about this issue.

I will also be writing about other aerodynamic issues relating to retardant and water drops. In some sense this planned series of articles will be a continuation of the short series of articles I wrote several weeks ago on wing stalls as relates to retardant drops. I won't link to this here, but if you look at the labels on the lower left side of this page, you will see a label that says "aerodynamics." If you click on that label you will get all my posts on aerodynamics to date, including posts on wing stalls.

Look for this series down the road a bit.

Erickson AirCrane: retardant and water/faom drops

Fixed-tank helicopters such as the AirCrane use Phos-Check 259F retardant, requiring that a mobile retardant base be set up near the incident. This happens on a regular basis with large fires. The video that I have embedded here shows an AirCrane using a dip tank to fill its fixed tank with retardant.

Being that the AirCrane can be used for retardant drops as well as water/foam drops, I asked Kenny Chapman when AirCrane is used for retardant drops in the U.S.:


Once the Crane is hauling retardant it is utilized the same as an airtanker. (Building retardant line ahead of the fire.) It can also switch back and forth between retardant, water and foam as needed. Retardant is not used in the initial attack role unless the helicopter is sent to a new fire directly from an existing incident that has a retardant plant set up already.

I asked him if there was ever a situation where a mobile retardant base was established where an AirCrane was working an existing fire and a “new” fire popped up near the mobile retardant plant. With a mobile retardant plant already set up near a “new” fire, was the AirCrane used to haul retardant in “initial attack.” He said:

I remember one that I did on a fire out of Santa Ynez around 2003 or so. Someone was smoking in fire camp and started a fire at the camp at exactly the time I was picking up a load. I was able to contain the new start with one load.

AirCranes carrying water/foam are frequently used in initial attack. The AirCrane has a separate foam tank, so after the pilot has filled the main tank with water he can decide whether or not to inject foam into the tank (already filled with water) based on the wants/needs/requirements of the incident commander.

Because the tank on the AirCrane does not have to be rinsed or otherwise cleaned out between retardant and water/foam drops, the AirCrane can go from flying initial attack with water/foam to flying extended attack with retardant once a mobile retardant base is set up near the incident.

S-2T: Retardant loading at Ryan AAB

Loading retardant onto the S-2 is a reasonably simple process. The yellow hoses in the photo are called pit supply lines, running from the storage tank to a high capacity, high volume pump. Each storage tank has it’s own pump. TL Stein tells me that “as the pump pulls the retardant from the storage tank it sends it into the pit supply line.” Once the pit supply is fully charged, the black loadout hose (see picture) is connected to the hot load at the tail end of the aircraft (see photo). The gate valve at the end of the load-out hose is gradually opened allowing the retardant to flow into the tank on the aircraft.

He explains how they know when the tank is full:

On some of the S-2T’s, there are a series of loading lights on the right side of the aircraft that light up to indicate how full the tank is getting. On others a mass flow meter is watched to indicate how much retardant has been pumped into the aircraft. As the aircraft fills, it will tend to settle due to the addition of weight and the tail will drop about six to eight inches. This settling action is not slow, but a rapid drop and signals the loader that the aircraft is getting close to full. When this happens, the loader will close the gate valve about halfway until either the full light lights up or the mass flow meter reads the desired amount of retardant has been pumped into the aircraft.

After the aircraft has been filled, the gate valve on the loadout is closed and the hose is disconnected from the aircraft. The ground crew leaves the area, and the plane is ready for take off.

Take a look at the annotated close-up of one of the panels in the cockpit. I will be talking more about the controls on this panel in my next post. On the top right, is a switch labeled “open - closed control for tank backflow valve.” This valve, also known as a flapper valve sits between the retardant tank and the hot load. To put it simply, the flapper valve seals the system. It serves three important purposes: (1) the valve is open when retardant is being loaded into the tank (2) when closed, prevents retardant in the tank from flowing back to the rear of the plane to the fill point, and (3) is left open when the retardant tank is washed out at the end of the season or when maintenance is necessary (more on this in a later post).

Recall from the post on S-2T specifications that the S-2T holds 1,200 gallons of retardant. There are times when the retardant tank will not be filled to capacity. One of these times is when it is very, very hot outside. TL Stein tells me that Ryan sits in a large basin, and when it is hot, it is very, very hot at Ryan. During times like this, the air density is lower. And when the air density is low, heavy airplanes do not fly very well. So, on a really hot day, the weight of the air tanker needs to be lightened. So, less retardant will be put in the tank on the S-2T. Retardant weighs about 8.5 pounds a gallon. Filling the tank with 1,000 gallons of retardant instead of 1,200 gallons saves 1,700 pounds. Lowering the weight of the air tanker by 1,700 pounds on a really hot day, according to TL Stein, makes a huge difference!

Still to come in this series of posts on the S-2T are (1) the retardant drop; (2) videos of the S-2T making retardant drops, and (3) cleaning out the retardant tank at the end of the season.

Retardant at Ryan AAB and S-2's

In today’s post I am going to be writing about retardant mixing at Ryan Air Attack Base (AAB). This is possible because I have learned about retardant mixing operations at Ryan AAB from TL Stein. Moreover, Ryan has an S-2 air tanker. This provides me with a unique opportunity to link mixing retardant with a specific type of air tanker. In addition, unlike Ramona AAB which uses a mobile mixing system, Ryan AAB has a permanent mixing system. Ramona, the oldest AAB, uses a (mobile) mixing trailer because they have little room for expansion. Ryan like many other larger AAB’s use permanent mixing facilities.

Ryan Air Attack was first used as an air attack base by the USDA Forest Service in 1957 and the California Dept. of Forestry (CDF) started air attack operations at Ryan in 1959, making Ryan the first joint air attack base in the U.S. In the 1960s a permanent retardant mixing system was installed and shared by both the USDA Forest Service and the CDF (now known as CAL FIRE). In 1998 the USDA Forest Service moved their air attack base to the San Bernardino International Airport.

Thanks to TL Stein -- who made a short video on retardant mixing operations, took some photographs and gave me an excellent write up of retardant mixing at Ryan -- I am in a position to make this blog entry. The video is included in this post. After you watch this short video, I hope that you will have a good idea of how retardant mixing at Ryan works.



In addition to the video, I am including a couple of TL Stein’s photos. One is a photo of an eductor assembly at Ryan where the water and retardant pipes are labeled. As you will learn in the video, as water flows through the eductor, it creates suction in the retardant pipe. Retardant is therefore drawn into the eductor. The powdered retardant mixes with water at the point (see the photo) where the water and retardant pipes come together. From there it goes into a storage tank. The second picture is of the retardant mix control panel where the mixing operation and flow of mixed retardant to the various storage tanks on the base.

In my next post, I will write a little more about the process of loading the retardant mixture onto the S-2 and share some of TL Stein’s up close and personal photos of the S-2.

drop patterns

The IAT website that I referred to in yesterday's post has a good SEAT training module (part 3) on fire operations. In other words the module talks about the parts of a fire along with different retardant drop patterns.

The module may be found here. Enjoy! I keep going back and reviewing this module, along with the one on fire behavior that I referred to yesterday.

The retardant drop

After the retardant is loaded, there is one thing that may be done before take off. That is, the ground crew who loaded the retardant onto the plane will wash down the side of the plane. This is necessary because the retardant will oxidize the paint and metal if it is not washed away. The ground crew moves away, the pilot is cleared to start the engine and then cleared for take off.

Moving to the fire itself, and before getting to the drop, I need to discuss two important people, One is the incident commander (IC). According to the glossary of fire terminology from the National Wildfire Coordinating Group, the incident commander is the “individual responsible for the management of all operations at the incident site.” The air coordinator is in an airplane flying overhead and is thus able to get a bigger view of the fire than the IC on the ground. The air coordinator looks at conditions that will affect the drop such as wind direction, hazards such as powerlines and trees, and if and how the drop will aid the fire fighting crews on the ground.

For example, the IC may ask for an anchor point on one of the flanks of the fire and allow the air coordinator or air operations (AirOps) to determine the optimal plan for the retardant drops. After AirOps has decided on the drop, they will tell the air tanker pilot exactly where to make the drop along with how much retardant to drop. Sometimes the pilot will make a dry run before making the actual drop, especially in cases where the pilot has not flown in the area on prior occasions. When the pilot is not familiar with the area, a dry run allows the pilot to scope out potential hazards that AirOps might have missed, look for escape routes, and get a feel for how the terrain might affect the wind. After the dry run, if any, is done, the actual retardant drop is made.

I would again like to thank TL Stein for our e-mail correspondence discussing discussing what happens from the loading of the retardant to the time the drop is made.

Terminology from the National Wildfire Coordinating Group

Anchor Point: An advantageous location, usually a barrier to fire spread, from which to start building a fire line. An anchor point is used to reduce the chance of firefighters being flanked by fire.

Flanks of a Fire: The parts of a fire's perimeter that are roughly parallel to the main direction of spread.
Incident: A human-caused or natural occurrence, such as wildland fire, that requires emergency service action to prevent or reduce the loss of life or damage to property or natural resources.

Incident Command System (ICS: The combination of facilities, equipment, personnel, procedure and communications operating within a common organizational structure, with responsibility for the management of assigned resources to effectively accomplish stated objectives pertaining to an incident.



Incident Commander (IC): Individual responsible for the management of all incident operations at the incident site.

Preparing retardant: part 2

I came across this link -- thank-you, TL Stein, to a web camera at the Ramona CDF Air Attack Base. The web cam takes pictures every two minutes 24/7. Look at the above image that I downloaded from the Ramona webcam, you will see a white tank and a red trailer. The red trailer is known as a mobile mixing unit. The white storage tank is the retardant holding tank. The retardant powder is mixed with water based on the manufacturers recommendations. Most of the time, the ground crews at the air attack bases do the mixing.

The simple explanation is that a trailer is filled with retardant powder. A water supply line is attached to the trailer. The retardant is mixed with water in a piece of equipment attached to the trailer called an eductor. After the retardant powder has been mixed with water it is pumped into the white storage tank.

For a more technical explanation of retardant mixing as applies to the type of equipment referenced in the above discussion, see this pdf document (requires a pdf viewer). According to TL Stein, the water tanks referenced in this document are no longer used and have been removed or altered into tool storage areas." 

Loading the air tanker comes next. The air tanker taxis into a loading pit, one of the ground crew releases vent plugs on the air tanker, a filler hose is connected, a valve on the filler hose is opened, and the retardant is loaded into the tank(s) on the tanker. There are a series of vent holes (with vent plugs) in the plane’s storage tanks. When the retardant reaches the desired level in the tanks, the retardant starts to spill from the vent holes. The valve in the hose is closed and the plugs are inserted to reseal the vent holes (see the attached photo)  And the plane, loaded with retardant is ready to go.

In closing, I should say that the simple scenario of mixing and then loading retardant is based on facilities, equipment, and aircraft at the CDF Ramona Air Attack Base using a Phos-Chek powdered retardant. The specifics of mixing and loading retardant onto the aircraft will vary depending on the brand of retardant, the type (liquid concentrate or powdered), equipment and facilities, and type of aircraft (SEATs, multi-engine air tankers, or helicopters). For example, to see a brief discussion of retardant mixing for SEATs go here.

Preparing retardant: part 1

Before an air tanker drops retardant on a fire, the retardant has to be mixed and loaded on the air tanker. In this post, I will write in general terms about the mixing of the retardant.

I would like to start by thanking TL Stein for our ongoing e-mail correspondence on aerial fire fighting. In this case, for his help in providing me with some information about the mixing and loading of retardants.

On the theory that a picture, or in this case a video is worth a thousand words, I want to start with this you tube video on mixing retardant. The video refers to retardant used by MAFFS C-130. I will be writing about the use of military C-130’s in aerial fire fighting in about a week or so. A special unit called the MAFFS is put on the back of the military C-130 before the plane can be used for retardant drops.

you tube video on retardants used by MAFFS

Prior to watching this video, I really did think that retardants were akin to “red goo”. Honest. I even used the “red goo” description in describing this aspect of aerial fire fighting because most have seen air tankers making retardant drops on various media clips. After watching the video I wonder if I am not so far off in thinking about retardants about “red goo.”

Some examples on different mixes of retardants

Manufacturers of retardants, foams, and water enhancers have recommended ratios or formulas for mixing their product with water. But I have learned that these ratios are not necessarily set in stone and different retardant mixes can be used depending on the fuel, steepness of terrain, etc. I asked TL Stein for some clarification on these ratios or formulas:

The mix ratio is never a set number, at least in my experience.  There is the manufacturers recommended formula and then there is the actual field numbers.  Retardant and foam are tested in a variety of fuels and conditions and the manufacturers mix ratio is generated using the average effectiveness for all fuel types and conditions.
 
In the field, under actual conditions, sometimes a thinner mix is better than the recommended mix and sometimes a heavier mix is needed.  I'll give you a few examples:
 
A. On a gently sloping hill, with light fuel (short grass and brush) and nominal wind, a lighter mix of either foam or retardant will be more effective as the penetration factor is minimal.
 
B. Same hill except fuel is heavy (old growth sagebrush w/ a 12 foot canopy) and moderate wind, both a light mix and a heavy mix will be used.  The light mix, being less gelled, will penetrate the canopy to affect the undergrowth.  A heavier mix will only be effective on the upper parts of the sagebrush because the gelling action is more sticky, therefore only adhering to the upper parts of the canopy and not reaching the bottom layers.
 
C. On a steep hill (45 degrees or more) with medium to heavy fuel and higher wind conditions, a heavy mix is best as this fire type will burn fast, usually burning just the tops of the fuel (crowning).  On initial attack in a forest, crowning is a major issue.  It allows the fire to spread more rapidly and creates additional hazards for ground crews (snags and widow makers). By treating the tree tops and upper parts of the fuels involved, it will slow the fire down allowing ground crews to be more effective in their efforts with hot spots picked up by helicopters.
 
D. New Jersey's conditions and fuel types are different than, say New Mexico's.  Fire will be fought differently in each place.  Tactics in one place will not always work in the other. 
 
Think of retardant and foam like dish soap.  Depending on how heavy the grease is will depend on how much soap you use.  I guess that was a simpler way of explaining all this.  In any case, retardant and foam mixing ratios recommended by the manufacturer are only guidelines.  Consideration of the local fuel types, weather conditions and past trial and error usage will generally dictate what mix ratio is the best.

 
Glossary (Fire terminology from National Wildfire Coordinating Group)

Crown Fire (Crowning): The movement of fire through the crowns of trees or shrubs more or less independently of the surface fire.
Initial Attack: The actions taken by the first resources to arrive at a wildfire to protect lives and property, and prevent further extension of the fire.
Snag: A standing dead tree or part of a dead tree from which at least the smaller branches have fallen.

A little more detail on retardant v. foam

I asked TL Stein about the differences between retardants and foams a while back, this is what he said:

RETARDANT:  Retardant is a combination of base elements designed to slow a fire down, not put it out, by nature of chemical composition.  By design and purpose, retardant (I'll use Phos Chek XA as an example), mixed in it's various degrees, consists of a gelatin, fertilizer, iron oxide for color, water, and a few other catalysts.  When mixed, the consistency is that of a thick pudding.  It's job is to coat the fuel to shield it from the fire.  While shielding the fuel, gasses are given off when heated that inhibit the oxygen from the fuel.  The iron oxide provides a color mark (red) as an indicator of where the drop was made and the gelatin is what goops the load, enabling it to stick to the fuel.  Ammonium phosphate acts as a fertilizer to promote new growth immediately after the fire, thus enabling the burn area to recover quicker and prevent possible erosion.  Drop altitude and airspeed are all factors in the effectiveness of a retardant drop.  As retardant is released from the aircraft, it breaks up by nature. 

If a drop is made too high, the retardant ends up becoming a fine mist by the time it reaches the ground, which reduces it's effectiveness.  If a drop is made too low, it doesn't have a chance to break up properly and usually creates a heavy coating on the fuel, destroying the watershed fuel by flattening it, and could kill any firefighter caught in the drop path.  Low drops will also destroy equipment in the path of the drop and is dangerous for the aircraft and pilot, as wind shear at low altitude can and will cause and aircraft to simply run out of air, stall and crash.  If a drop is made too fast, the retardant will start to break down due to the increased airspeed and become a mist, just over a larger area.  There is a set criteria for air tankers and how drops are to be made.  Airspeed and altitude are now figured by computer, onboard most tankers.  The tank doors open to adjust to these two factors providing with the ideal amount of release of retardant in relation to the aircraft performance. Keep in mind, the computer does not control the aircraft, rather, it reads the altitude and airspeed and adjusts the retardant drop accordingly.
 
FOAM: By nature, foam physically smothers a fire.  While not having all the same properties of a retardant, some foam products do have a minimal retardant capability.  Foam allows a deeper penetration on certain fuel types and it's effectiveness dropped from an aircraft varies on the fuel type involved and fire behavior. While never having used any foam product in my working experiences (other than training for aircraft crashes and fuel fires), my working knowledge of foam is limited.  I do know that foam is a good pre-treatment for brush as well as structural protection from spotting ahead of the fire.  Even if the foam dissipates after application, it's effectiveness is still valid for a short period of time, however, not as long as a retardant.

Glossary (Fire terminology from National Wildfire Coordinating Group)

spotting: Behavior of a fire producing sparks or embers that are carried by the wind and start new fires beyond the zone of direct ignition by the main fire.

About retardant, foams and water enhancers: part 2

The USFS has a great deal of information about the various wildfire chemicals -- retardants, foams, and water enhancers that you can access through their wildfire chemical systems page. I will let you explore at your leisure if you care to. However, I do want to include one piece of information for each of the three types of chemicals. That is a sheet listing the different brands they use and how they are used (SEATs, multi-engine tankers, helicopters, engines). I found this information interesting and I thought that you might too. Note that I am writing about how this chemicals are used in aerial firefighting by SEATs and/or multi-engine tankers. Note that all of these sheets require a pdf viewer.

One of the manufacturers that the U.S. Forest Service contracts with for wildfire chemicals is a company called Phos-chek. They have webpages for each of the three different types of wildfire chemicals with some good information on how each is used. So as to not show any favoritism, Firetrol makes all three types of chemicals. And there is thermo gel, a water enhancer.

Retardants

Long-Term Retardants—U.S.D.A. Forest Service
Phos-chek retardant

Foams

Class A Foams—U.S.D.A. Forest Service
Phos-check class A foam

Water Enhancers

Water Enhancers—U.S.D.A. Forest Service
Phos-chek water enhancing gel

Some of the links on this page are to USDA Forest Service webpages. I think that they may be doing some site maintenance and/or updates to their server. I had some difficulty accessing their site earlier today. So, if the links don't work, check back later and they may work. All links worked as of 5:45 PM EDT on March 12.

About retardant, foams, and water enhancers: part 1

Recently when referring to chemicals that are dropped on fires by SEATs or multi-engine tankers, I was referring to retardant drops. However, I think that there are three different types of wildland fire chemicals used in aerial fire fighting. These are long-term retardants, foam fire suppressants, and water enhancers. Definitions of these three chemicals can be found on this U.S. Forest Service webpage.

If I understand correctly, foam fire suppressants do what the name implies, suppressing fires. I have written elsewhere in this blog about the AgCats owned by the contractor, Downstown, that has the SEAT contract with the NJ Forest Fire Service. I am fairly certain that the AgCats use a foam fire suppressant. Water enhancers are also suppressants, I understand that water enhancers can be quite effective when used in air tanker drops. Retardants, which are usually colored red, retard or slow the growth of the fire.

In my next post, I will provide a little more detail on the three chemicals used in aerial fire fighting.