Large Air Tankers vs Very Large Air Tankers


CAL FIRE’s fleet of 22 S-2T air tankers, with their 1,200-gallon tanks, are the agency’s largest aerial firefighter.  So, it relies on contracting a fleet of bigger aircraft to put the larger fires out.  Like the ones that dominated the southern California skyline during October and December. When big fires were getting a deadly grip in the wine-rich Napa Valley in California during the autumn, CAL FIRE Spokesman Bryce Bennet told FOX 40 TV Channel "If the fires go on longer and becomes a much larger incident, sometimes our aircraft aren't the right tool for the fight, and that's where we go to the larger air tankers."


Two types of contracts


During 2017, CAL FIRE issued CWN contracts to company’s operating the Large Air Tankers (LATs) or Very Large Air Tankers (VLATs).  It led to the likes of 10 Tanker (DC-10s), Global SuperTanker (Boeing 747), Ericson Aero Tanker (MD-87s), Coulson Aviation’s Air Tanker (C-130 Hercules), and Neptune Aviation (P2V and BAe 146) all joining the fight.


Generally, there are two methods of meeting CAL FIRE’s aerial firefighting requirement if its looking for an alternative to its S-2Ts.  They are Exclusive Use contracts or Call When Needed (CWN) contracts. CAL FIRE, with few exceptions, relies on the CWN contracts to supplement their S-2T fleet.  The Forest Service uses a combination of Exclusive Use and CWN contracts.  The air tanker companies are not so keen on CWN contracts.

Dan Snyder, Chief Operating Officer (COO) of Montana-based Neptune Aviation Services which owns nine firefighting BAe 146s told the author how the contracting system works. “Historically, CAL FIRE operates its own aircraft so they generally issue Call When Needed contracts to fill in for the S-2 fleet.  We were in an Exclusive Use Contract with the state of California with one of our BAe 146 large air tankers, but it ended on December 31.  


Owning a VLAT would be prohibitively expensive for CAL FIRE, which restricts most of its operations to California. The agency instead offers CWNs to the VLAT companies, which is a risky way of running a business.  Snyder continues: “While it pays very well when used, operating your company in this manner without the security of regular income doesn’t provide a long-term future.”

A CWN dictates a company has 24 hours for initial call up, while an Exclusive Use contract has a specific Mandatory Availability Period in which the aircraft is available every day for a minimum of 9 hours at a specified location.  Snyder, Neptune’s COO since January 2010 adds: “The risk goes to contractor, operator and builder of the asset.  It works well with helicopters, where one day it can be firefighting with a bambi-bucket, then another day hauling equipment on to buildings or logging. The airtanker only has one mission, that being to drop water or retardant on wildland fire. 

“CWN drives prices up, because the operator doesn’t know how long it will be flying. You cannot operate longer term, because no financial institutions will finance you.  The problem is how do you invest, how do you hire when you don’t know when you are going to work and financial institutions are reluctant to fund additional growth within a company based on CWN contracts.   So not knowing when you are going to get paid really disrupts your revenues and budgets. In the short term, the company gets a great amount of money, but it doesn’t work for either side longer term.”

Snyder sums up the Exclusive Use contract: “It provides an exclusive mandatory availability period when you are on contract and will be paid, unless the aircraft breaks.  “The USFS and CAL FIRE pay a daily availability rate (DAR), so the aircraft and pilot will sit on alert and be ready to fly. The DAR needs to cover all the costs of crews, maintenance of aircraft, other overheads and taxes. 

“On top of that you get a flight rate, when the aircraft actually flies.  That should cover all the associated costs related to flying the aircraft like time being used on engines, on landing gear.  The contracting has a guaranteed asset, that they can do what they want with, on contract.

“When the Napa Valley fires broke out [October 8-27], California was looking for any and every asset it could get its hands on.  At that time of the year, Neptune aircraft were still under Exclusive Use contracts with the US Forest Service.  When CAL FIRE called, we didn’t have anything but P-2s available. Only a week earlier we had held our P-2 retirement event, so instead we returned two P-2Vs to service and sent them to California.”

A lot of competition

Aerial firefighting is a very competitive business, where contractors provide fixed wing aircraft to agencies like the USFS, US states and other countries.  But it is important to understand that every aircraft has its positives and negatives, as you will read shortly.  Normally, CAL FIRE would contract the 3,000-gallon Bae 146 to augment its own

S-2T air tankers. Both can rapidly respond to smaller fires and then return to base easily when they are not needed, with minimal cost.  The 146’s primary mission is for initial attack (attacking fires which have just started) but can be used for extended attack (part of a team trying to put out a big fire) too, which is what the Neptune 146s were used for.

There is a myth that Very Large Air Tankers (VLATs) dump retardant or burn fuel to reach their minimum landing weight.  “This is just untrue,” according to Rick Hatton, the Founder of 10 Tanker Air Carrier which operates two DC-10 VLATS. aerial firefighting aircraft.  “You don’t want to run that operation with a big aircraft or one that cannot land fully loaded with retardant, if it is not used. This is an expensive enough business. In our history of over 3,000 flights we have only had to jettison retardant three times.  They don’t launch us unless they have a fire they want us to put out, and if we can’t be used on that fire they will divert us to another fire which is always the case. So those people that say VLATs cannot land loaded is missing the point.” 

Snyder agrees the VLATS – DC-10 and Boeing 747 are great aircraft for certain subsets of fire missions.  “They work really well for dropping big loads of retardant,” then adds, “The VLATs might be able to drop 10 or 11, 000 gallons loads, but if your running ridge-to-ridge 400ft above the valley floor, that valley floor isn’t going to get the coverage it needs.  So, the VLATs work great in rolling hills and flat land, but not so good in intense mountains, and ridge line drops.  The laws of physics, say you can’t point a multi-ton VLAT downhill into a valley and turn it around and bring it back out, even if it has tons of power. 

“You have to be very careful where you put those aircraft.  Smaller LATs like the 146 can get down low into the valley floor and canyons and put in a line for whatever they need to reinforce.  That’s the fundamental difference between the LAT and VLAT. The 146 is smaller but doesn’t have the weight, so inertia doesn’t get in the way but instead they can go into places you wouldn’t put a big tanker”.


However, Hatton totally disagrees,” The DC-10 can go everywhere and more than 146.  We can put it into valleys and routinely drop at 200ft above ground and the myth that a smaller aircraft is more manoeuvrable is totally wrong in an aerodynamic sense.  Aircraft are as manoeuvrable as a function of their power to weight ratio.  The DC-10 excels over the 146 by a huge margin because it doesn’t have 12 hours of fuel on board which it was built to take.    So, we launch with a full load of retardant with 60% of the usable lift that the aircraft used to accommodate as airliner, with three hours of fuel - we have extreme vertical performance.  Size has nothing to do with performance.


Very Large Air Tankers can drop an incredible amount of retardant.  The 10 Tanker DC-10s have been modified to accommodate a 11,600-gallon tank.  It would take ten Trackers to drop that much retardant!  10 Tanker’s Rick Hatton, who found the company in 2002, told the author: “It is an extensive modification, the DC-10-30 has a significant amount of room underneath it so the tank is big.”

Looking at the tankers dropping the retardant, it seems to be a case of opening-up the tank door and letting the load go.  But it isn’t that simple.  When asked how long it take to drop the load, Rick explains that the number varies. “You drop according to the direction offered by the Incident commander via the Attack Supervisor in the lead plane (usually a King Air).  They dictate the coverage level they want, which is defined by the number of gallons per hundred square feet of real estate, and it tends to be gauged between two and eight”. 

“The higher numbers are used for denser terrain like forests, and the lower ones are for rolling terrain where there is grass or live-stock feed.  Coverage level 6 we would drop a line of about a mile in length which would take about 15 seconds.  We could drop coverage level 8 in about eight seconds with heavier concentration but in a shorter space.”

Meanwhile Global SuperTanker’s Boeing 747 with its 19,000-gallon capacity, played a big part in dousing the California fires, when deployed to Sacramento on December 5, 2017.  During its ten sorties, and eleven drops, a staggering 175,950 gallons of retardant was unleashed onto assignments in Thomas and Liberty.  The massive jet, which always attracts the TV cameras when it gets to work, departed Marana-Pinal Air Park, Arizona on December 22.  It was there, undergoing routine maintenance and returned afterwards.  Normally it is based in Colorado Springs, Colorado.

During the interview with Fox 40, CAL FIRE’s Bennet commented: "Having the 747 in our tool box allows us to lay down a substantial amount of retardant in a short amount of time over a large area."  However, at a reported cost of $16,000 per hour to CAL FIRE, it is an asset which has to be called in as a last resort – but when there are billions of dollars of property at risk, it has ultimately to be worth it. In the past the Boeing 747 has put fires out in Israel and Chile, and Global SuperTanker like so many US aerial firefighting companies is bidding to export its unique services.

Europe next?

Many countries around the world, including France, Portugal and Spain are suffering an increasing number of wild fires during the summer. The US and Canadian aerial firefighting companies can provide an alternative option to the Bombardier 215/415s generally in use across Europe. With tightening budgets and CAL FIRE looking at future strategic alternatives to its current way of working, Europe is now a possible destination. France’s Sécurité Civile is currently looking at options to replace its S-2 Firecats in 2022, we could see these new generation LATs and possibly VLATs flying over Europe’s fires one day.        

Aerial Firefighting North America


Chief Ken Pimlott, Director, and Dennis Brown, Chief of Flight Operations at CAL FIRE, are set to speak at the Aerial Firefighting North America Conference between 12 and 14 March in Sacramento.  While Global SuperTanker, 10 Tanker Air Carrier, Neptune Aviation and Viking Air will exhibit on the show floor.  For further information and daily event agenda, please visit