Lockheed P-3 Orion

Before I begin, I want to discuss some terminology. For brevity, when I write about multi-engine air tankers, I will use the term air tanker(s). If for some reason I need to refer to single engine air tankers, I will use the term SEATs (as I have been doing in recent entries). I believe that st. miles refers to statute miles. The number of gates refers to the retardant drop hardware on the air tanker. I thought it useful to define what an air tanker is and found this definition on an Interagency Airtanker Board webpage: “An airtanker is defined as an aerial delivery system configured for the purpose of dispensing water, fire retardant, or fire suppressant material from a fixed tank that controls the rate of delivery. The aerial delivery system includes the tank system and the aircraft.”

Finally, I again want to thank TL Stein for his help in providing me with the specifications and other pertinent data and information about the various air tankers that I am writing about.

The Lockheed P-3, like many other types of multi-engine air tankers used for aerial fire fighting, both currently flying and those “retired” from active service, are former military aircraft converted for use as air tankers. A four-engine turbo-prop, it’s military use was for submarine surveillance by the U.S. Navy. The military version, know as the Lockheed P-3 Orion was first put in military service around 1961. The wings sit low on the fuselage. It is a fast aircraft, can take-off on a shorter runway, can carries three thousand gallons of retardant.

Those of you who might be familiar with the air tankers currently under nationwide contract here in the U.S. might be aware that the Lockheed P-3 Orion was the successor to the U.S. Navy’s Lockheed P-2 (aka P2V) Neptune. The Lockheed P2V was also converted for use as a fire fighting air tanker. Given that the P2V has been around longer (first in service around 1945), it might make sense for me to write about the P2V first. I am unable to do that as I have a little more work to do before I write about the P2V. But stay tuned. The write up of the P2V will be coming soon.

Back to the Lockheed P-3.

Specs:

length (ft): 106
wing span (ft): 99
turning radius (ft): 65
cruise speed (mph): 275/320
range loaded (st. miles): 2,300
gross weight (lbs): 105,000
contract op.wt (lbs): 97,000
retardant loads: 3,000 gallons
number of gates: 1

Aero Union is the sole operator and fabricator of the P-3. In 2008, they had eight P-3’s on the federal contract air tanker list. You might want to spend a little time exploring their website to learn more about their P-3’s. Posting urls to specific web pages does not seem to work well, so I have not done this. However, if you click on flight operations in the menu on the left hand side of the page you will go to the flight operations web page where you may click on a link for aerial firefighting to learn more about their P-3 based aerial fire fighting program.

Aero Union also has a good P-3 photo gallery with some good shots of their P-3’s in action. From their main or home page, click on photo gallery to go to their main photo gallery then click on “Aero Union’s P-3’s in action”.

There are three good, short videos of P-3’s in action on you tube:

Tom's Branch Fire Retardant Drop
Bear Divide Hotshots, 2006

Updated on August 3, 2015: The US Forest Service terminated its contract with Aero-Union for their Lockheed P-3's, going out of business a month later. (see my articles of July 30, 2011, August 17, 2011, and January 18, 2012). The link to Aero Union's old website no longer work.

Updated on November 30, 2017: New link to Interagency Airtanker Board

C-130s in brief and reordering of upcoming air tanker postings

When I originally planned out my postings on different types of multi-engine air tankers available for nationwide aerial fire fighting, I was going to start with the C-130. As I began to learn more about these different aircraft, I learned that the civilian C-130 air tanker fleet has been grounded due to maintenance problems and some tragic crashes of civilian C-130’s. Newer and meticulously maintained military (Air Force) C-130’s, aka the Modular Airborne FireFighting System (MAFFS) are called into service only when all other multi-engine air tankers are in use and more are needed.

As I sat down this morning to write my first couple of air tanker postings, I decided to revisit the order of my postings. As the military C-130’s are only called into service for retardant drops if all other air tankers are in use, it made sense to write about the military C-130 aircraft only after I have written about “civilian” air tankers currently on nationwide contract for aerial fire fighting.

Intro to multi-engine airtankers

In addition to SEATs and helicopters, multi-engine air tankers are available for aerial wildland fire fighting support. The Interagency Airtanker Board maintains a list of SEATs, helicopters, and multi-engine air tankers that are certified for fire fighting. This is a list of specific aircraft by tail numbers. The tail numbers are tanker numbers, two or three digits, assigned by the Interagency Airtanker Board.

The aircraft on this list are available for nationwide contract, but it does not mean that they actually fly. The only aircraft that fly are aircraft that are listed as being under nationwide contract.

For example, I have a copy, now outdated of the 2008 Federal Contract Airtanker List, these were the listing of the 21 multi-engine air tankers available for nationwide contract in 2008. If I understand correctly, these air tankers are moved around the country dependent on the fire seasons. For example, there may be more air tankers available in the south during the spring that will be moved out west for fire season out west.

The 2009 Federal Air Contract Airtanker List is not available yet. At least I don't have a copy. If and when I can find a copy on the web, I will include a link in a later blog entry.

Over the next three weeks or so, I am going to be writing about various types of air tankers, including but not limited to those that were available for nationwide contract in 2008. Most multi-engine air tankers are former military aircraft converted for use for firefighting. In some cases, the conversion did not go well. I will include one or two of these cases.

Finally, I will include air tankers owned by state fire fighting agencies including California, North Carolina, and Minnesota. In the case of state-owned (or contracted) multi-engine air tankers, it is difficult to find specific information on the web. California may be in class by itself. I found information about Minnesota and North Carolina in my wonderings on the web.

So stay tuned.

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.

fire behavior

Tomorrow I will be posting a link to an Interagency Aviation Training (IAT) module on SEAT firefighting tactics. I don't know the specifics of the IAT online modules nor do I know much about certifications and (re)certifications that airtanker pilots and helicopter pilots go through. What interested me in this site, was that I learned something from looking at certain modules.

With this in mind, I thought I'd post a link to the module on fire behavior. This is the first of four modules on SEAT training. By the way, the module for helicopter training is almost identical. I have looked at this module a couple of times, spending about fifteen to twenty minutes on my first go around. It requires the adobe flash player, and you can move backwards and view a slide again.

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.

avoid stalls during retardant drops

Remember the two stall speeds that I referred to for the AT-802F that I referred to here? There is a V-speed or velocity-speed known as Vs where Vs is the stall speed or minimum steady flight speed for which the aircraft is still controllable. As you can see from this wikipedia article on V speeds, there are many different V-speeds. Now, if I am thinking about this correctly, then Vs should be slightly higher then this AT-802F performance specification:

Stall Speed, Flaps Down: 91 mph (146 kph) at 16,000 lbs (7 257 kg)

The speed that an airtanker flies at when making retardant drops on a fire is related to Vs. This is expressed as a formula (1.3*Vs). According to the specs found on the Queen Bee web site, the drop speed is in the 120 to 130 mph range. For a more detailed discussion of the calculation of the drop speed (from which I based this discussion) using the AT-802 as an example, go to this BLM aviation page, an automatic download of a MS word document.

TL Stein offers this explanation of stalls, retardant drops, terrain, and fire-produced weather:

Stalls are to be avoided in ALL cases, excepting the landing phase of an aircraft.  In the air tanker world, landing is the only place you want a STALL.  Fire produces it's own weather conditions.  A tanker making a drop in a canyon can experience a tailwind on approach to the drop, which drops the forward airspeed.  Over the fire, a severe lift condition can and does occur, due to the heat raising from the fire.  During the drop phase, the aircraft releases it's load and becomes much lighter.  Consider the thermal wind activity over the drop zone, combined with a sudden tail wind.  The aircraft can loose enough forward airspeed over the wing to cause it to stall and crash.  This is why airspeed / drop speed are critical to the aircraft and the mission.  In the real world, stalls are practiced at a good altitude to enable a successful recovery.  This is mandatory for a "type rating" in the aircraft you will be certified to fly.  Stalls close to the ground, in a fire fighting scenario leave no room for recovery.  There are a lot of memorials to pilots who stalled and crashed.  Why?  Constantly changing conditions over the fire is a good start.  You can make two passes over a fire and the flight conditions will never be the same on each pass.  The best tanker pilots on earth know this.  Each drop you make you run the risk of something going wrong, it's a given and we know it.

stalls and icing

One of the factors that can contribute to stalls is icing on the wings and tails of an aircraft. Simply, ice formation interferes with the normal aerodynamic flows over the wing and tail (aka horizontal stabilizer) leading to lower stall speeds and tragic outcomes. Yes, there are various de-icing systems that can be used in flight such as de-icing boots to rid the wings and tail of ice during flight. It is not my intention to get into the world of de-icing an in-flight aircraft.

In my travels on the internet learning about stalls recently, I happened on a link to aviation safety at a US Forest Service website and found a safety advisory from the Interagency Airtanker Board on icing. I found these safety reminders for airtanker pilots to be very poignant. As I read this advisory, what came home to me is that an airtanker pilot has the right to say “no” to flying into a situation where icing might be a problem and/or to get out of an icing condition before making a drop if called for.

Of course, I don’t know enough to know if airtankers even do retardant drops in northern States in America during cold weather where icing might be a problem. I am not an expert in meteorology, but I know enough to know that 33 degrees on the ground is going to translate to something colder at higher elevation. I also know that there is something called rime ice, which I think is caused by “freezing fog.” And rim ice can form on aircraft wings and tail.

Link to IAB safety advisory on icing (this is a pdf filerequiring a pdf viewer)

If that link does not work, go here and look under Interagency aviation safety alerts for advisory FS 09-01 on aircraft icing.

The advisory also provides a good description on ice formation as affects aviation that I found very helpful.

good animation on aircraft stall

TL Stein sent me this awesome animation illustrating some of the concepts that I have been writing about. It may be found here. Note that the animation may take a couple of minutes to load.

Aircraft lift

I am moving on from writing about SEATs. I want to spend some time talking about retardants that airtankers -- SEATs and multi-engine airtankers -- drop on wildfires. But, before doing so, I need to spend some more time on the aerodynamics underlying “aircraft stalls” for reasons that I hope will be apparent in later posts. I will be spending a couple of weeks on this sequence of posts before I move on writing about multi-engine airtankers around the third week of March.

To review, I wrote about stall speed in my post of February 12:

“As I understand it from my correspondence with TL Stein, stall speed for an aircraft is the speed where the forward speed of the aircraft is not producing enough air flow over the wings to produce lift or support the airplane at its altitude.

When a pilot is landing an aircraft, the plane is just over stall speed.”

The engine provides the power or thrust to move the aircraft forward through the air, but it is the aerodynamic properties of the wings that provide the lift: chord, dihedral and anhedral, wing loading, and the shape of the top and bottom of the wing. The leading edge of the wing is thicker than the trailing edge. Recall that the flaps are usually on the trailing edge of the wing. The distance from the leading edge of the wing to the trailing edge of the wing is known as the chord.

Dihedral is the angle, usually upward of the wings of an aircraft in relation to the body of the aircraft. The wings of a bird also are dihedral. Anhedral are when the wings are at zero or negative dihedral. See this wikipedia article on dihedral for a more detailed explanation and some pictures.

Wingloading is the loaded weight of an aircraft divided by the wing area. TL Stein tells me that “the chord, length and ‘hedral aspects determine the amount of lift that can be generated by the wing for any given aircraft.

But, we are not done with lift yet. The standard wing design is a curved top and a smooth bottom, creating a high pressure area under the wings and a low pressure over the wings. TL Stein explains:

“the faster the air moves over the wing, the more lift is created. Air speed is in direct relation to lift. Lift enables flight. Lose lift and the aircraft sinks, When the forward airspeed no longer produces enough low pressure over the top of the wing to sustain flight . . . this is stall.”