Aerial Firefighting Management Is There A Better Way

 

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Aerial Firefighting Management Is There A Better Way

By Daniel Baxter

 
 

September 30, 2009, Fighting forest fires poses a number of problems for fire management teams. Forest fires generally occur in remote, heavily wooded areas and in most cases are not easily accessible by vehicle or foot and don’t present an immediate water supply to assist in firefighting.

For this reason, aircraft and helicopters have been used since World War II in aerial firefighting by flying in smokejumpers and for dropping fire retardant and or water on a targeted area. A smokejumper is a wildland firefighter that parachutes into a remote area to combat wildfires.

In order for aerial firefighting management teams to be successful, it requires that aircrafts drop huge amounts of water and or retardant onto its target. It is estimated that upwards of 80 percent of the water dropped by a helicopter or aircraft does not reach the fire or its target. This is due to what is known as “erosion”.

 

As water is dropped through the air it will begin to vaporize. If there is a heavy wind, either caused by the fire or metrological conditions, the water and or retardant can be blown off  its targeted area. Guar gum and clay are thickening agents used to reduce erosion dispersal of the water or retardant after it is dropped from the plane. These chemical agents help to cut down on the erosion effect.  

It is critical that when water and or retardants are dropped that it reaches its target area. For this reason a color dye is added to water or retardants to make it easy for the pilot to see where his/her load is being dropped. The most common color is red however, blue and yellow are also used. 

Early fire retardants were mixtures of water and thickening agents, and later included borates and ammonium phosphates. Borates are no longer used as it is toxic to animals and sterilizes the soil. Today, companies are using ammonium or ammonium polyphosphate with attapulgite clay thickener or diammonium phosphate with a guar gum derivative thickener. These agents are less toxic to the environment and act as a fertilizer to aid future regrowth of vegetation.  

 

K. Kemper who writes for the Associated Content wrote a piece called, “How to Put Out Any Forest Fire In 6 Hours.” Kemper examined the techniques used by city firefighters battling building fires. He found two simple common threads exist; a fire truck and multiple hoses allowing for focused water against a fire.  

Kemper's solution was simple. His idea was to place a water tank with a controllable waterjet nozzle in the cargo bay of a helicopter. The nozzle could focus water and or repellant onto the targeted area in order to reduce aerial firefighting water drops erosion and to get water to the target area. The helicopter could fly at a low enough altitude as to stay clear of heat and obstacles and achieve the goals of reducing erosion and get the water onto the targeted area.  Kemper further suggests that helicopters could fly in formation, as one helicopter dumped its load, the next helicopter would then move into position.

It would appear that this could as well be done on aircraft at “slow flight.” We have seen military aircraft equipped with guns, surely these guns could be replaced with controllable waterjet nozzles.

There are many variables that must be considered in dealing with Aerial Firefighting Management. There certainly is no quick fix answer. However, Kemper's idea certainly is an idea that should be considered.  

In mountainous areas it is difficult for aircraft to fly at low enough altitudes to fight fires. This is an area where pilots can experience downward drafts and winds of 40 MPH and above, conditions that are conducive to an aircraft stall. As many of us know, look out for lenticular (lens shaped) clouds on the downwind side of a mountain. This is a sure sign of downdrafts and you can expect mountain waves on the leeward side of mountains.

In addition, fires can also cause updrafts and downdrafts. Aircraft or helicopters at too low altitudes that encounter downdrafts can find themselves in a stall and crash.

 
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