question: Why do large scale fires take so long to be put out?
comment: Thats happens because of how the fire works. In order for fire to burn, you need fuel, heat, and oxygen. Now, its not enough to just locally remove oxygen or energy for a moment. You need an orchestrated effort to keep situation controlled until its all extinguished. If you dont, dangerous things happen (like, for example, backdraft, if you let the fire smoulder in a closed, heated room, and let the oxygen back in - and thats how many firefighters died, too). Even house fires generate temperatures close to 1000 C easily. And, you cannot just drop several tens of tons of water down. You'd obliterate the building if you did so. Which kinda defeats the purpose of saving as much as possible. And im not even getting into specyfic situations like dealing with chemicals (even cooking oil fire on the frying pan - dont douse that with water, because it will be quite violent/explosive!) or high (or even standard 220V) voltage systems fires...
passages: Firebombing improves the chances of a first attack on a bushfire being successful by up to 50 per cent when the Fire Danger FFDI ranges from moderate to high (24). However, the chances of success fall rapidly as the fire danger index rises, fuel loads increase and delays in reaching the fire extend. For example, the probability of success drops to less than 20% if the FFDI is severe (50) and the delay is more 30 minutes. These figures are significantly affected by the presence or absence of ground crews.
  
  Limitations of firebombing are often determined by:
   BULLET::::- 1972Fire broke out in the Sunshine Mine in Kellogg, Idaho, on the morning of May 2; 91 workers died from smoke inhalation or carbon monoxide poisoning
  
  BULLET::::- 1986Fire in a gold mine owned by the General Mining Union Corporation in Kinross, Transvaal, South Africa, with 177 killed and 235 injured on September 16
  
  BULLET::::- 1988"Piper Alpha" oil platform disaster, North Sea, on July 6; 167 deaths
  
  BULLET::::- 1991Kuwaiti oil fires following the Gulf War
  
  BULLET::::- 2010Explosion and fire on the "Deepwater Horizon" mobile offshore drilling unit in the Gulf of Mexico
   Firebombing is not generally effective against high intensity, fast moving bushfires. The upper limit of fire intensity is estimated to be about 2,000 kW/m in eucalypt forest fuel which roughly equates to the limits which can be handled by either ground crews alone or ground crews supported by fire tankers, graders, bulldozers, etc. Severe bushfires, such as on Black Saturday, generated intensities in excess of 100,000 kW/m, whereas prescribed burns are usually less than 500 kW/m. For comparison, a large household radiator emits about 1 kW.
   Firebombing fails on its own as a containment strategy if the fire behaviour includes medium or long distant spotting.
   The effectiveness of aerial firebombing is complex and depends on many factors including: aircraft turn-around time, distance from fire, aircraft type (fixed wing vs rotary), aircraft performance, load size, terrain, drop characteristics, drop door system, ambient weather conditions, wind, availability of ground support, fire intensity, fire size, fuel type, pilot skill and suppressant used.
   Section::::Conservation.
  
  Section::::Conservation.:Role of Forestry Department.
  
  The Forestry Department provides the cedar forests with protection from damaging fires. Each year at the beginning of the dry season hundreds of kilometers of firebreaks are hoed clean of vegetation to provide barriers which will impede the advance of fires. In addition early controlled burning is carried out to reduce the buildup of combustible material which could otherwise cause very intense and damaging fires later in the dry season. For further safety fire standby gangs equipped with fire fighting equipment are stationed on each of the plateau areas whenever there is a fire hazard.
   One of the major hazards associated with firefighting operations is the toxic environment created by combustible materials. The four major risks are smoke, oxygen deficiency, elevated temperatures, and poisonous atmospheres. Additional hazards include falls and structural collapse that can exacerbate the problems encountered in a toxic environment. To combat some of these risks, firefighters carry self-contained breathing equipment.
  
  The first step in a firefighting operation is reconnaissance to search for the origin of the fire and to identify the specific risks.
  
  Fires can be extinguished by water, fuel or oxidant removal, or chemical flame inhibition.
  
  Section::::History.
   There is ample evidence and general consensus amongst firefighters about the effectiveness of deploying aircraft for aggressive initial attack to keep fires small or to provide tactical air support for fire crews on the ground. In California, the US Forest Service has an annual expenditure of about US$200 million to suppress 98% of wildfires and up to US$1 billion to suppress the other 2% of fires where initial attack fails and they become large.
   Plans had been in place to start using foam at midnight on 11 December, but were delayed by last-minute concerns over possible pollution of local rivers and underlying water sources. Six high volume pumps were used to extract of water per minute per secondfrom a reservoir from the fire, with six more high-volume pumps deployed at various locations to serve as boosters. Thirty-two thousand litres (7,039 imp gal) of fire fighting foam per minute were directed against the fire for just over four hours, after which the pumping rate was reduced. Half of the 20 individual fires were reported extinguished by midday.
   BULLET::::- 1975Fire on the Lüneburg Heath in north Germany, 80 square kilometres destroyed, 7 fatalities including 5 firefighters killed on August 10
  
  BULLET::::- 1983Ash Wednesday bushfires killed 75 people and injured more than 2600 others in South Australia and Victoria.
  
  BULLET::::- 19871987 Daxing'anling wildfire in People's Republic of China, burned for a month
  
  BULLET::::- 1988Yellowstone fires of 1988 largest, most expensive wildfire in the history of the National Park Service, at the world's first National Park
  
  BULLET::::- 1994Isabela Island forest fire, Galápagos Island, Ecuador, 12 km² lost in April.
   Moreover, much of eastern Victoria and alpine parts of NSW are remote, mountainous and inaccessible and bushfires are often caused by multiple lightning strikes which can grow quickly in size. Even with the aid of modern firebombing aircraft to slow the spread of a bushfire, the control of these fires usually remains reliant on ground crews getting to the fire edge to extinguish it completely. Although, heavy rain is sometimes sufficient.
   Depending on the environmental conditions, and the relative effectiveness of a given firebreak, firebreaks often have to be backed up with other firefighting efforts. Even then, it is still sometimes possible for fire to spread across a seemingly impenetrable divide. During the worst part of the fire season in southern California, strong Santa Ana winds were observed to blow carpets of burning embers across eight-lane freeways. During the 1988 fires in Yellowstone National Park, hot embers managed to cross the Lewis Canyon, a natural canyon up to a mile wide and 600 feet (180 m) deep. In Australia, firebreaks are less effective against eucalyptus forest fires, since intense fires in tinder-dry eucalyptus forest spread through flying embers, which can be carried by the winds to trigger new blazes several kilometres away.
   BULLET::::- On 27 July, the fire had covered . At that time, it was only 5 percent contained despite all the manpower and equipment that was deployed on the fire.
   Aircraft can be very effective at slowing a fires rate of spread burning in remote locations giving more time for the arrival of ground crews. In a few cases firebombing has been sufficient to extinguish small fires such as a single trees or very small spots. Firebombing aircraft play an important role but there is no substitute for "boots-on-the-ground". However, firebombing with foam can very effective at extinguishing grass fires in open farmland, protecting houses by knocking down flames or working in conjunction with ground crews.
   However, rising costs of large firebombing aircraft have led some critics to question the strategy of relying on them for prolonged attack operations on relatively stationary fire fronts or for building lengthy retardant control lines. Some argue for more expenditure on fuel reduction burning or using more smaller, less costly, agricultural firebombers instead.
   Large fires often become extended campaigns. Incident command posts ("ICP"s) and other temporary fire camps are constructed to provide food, showers, and rest to fire crews.
   Controlled burns on Australian or USAAA savannas can result in an overall reduction of greenhouse gas emissions. One working example is the West Arnhem Fire Management Agreement, started to bring "strategic fire management across of Western Arnhem Land" to partially offset greenhouse gas emissions from a liquefied natural gas plant in Darwin, Australia. Deliberately starting controlled burns early in the dry season results in a mosaic of burnt and unburnt country which reduces the area of stronger, late dry season fires. Also known as "patch burning". To minimise the impact of smoke, burning should be restricted to daylight hours whenever possible.
   Cases also exist where the ignition factor is not the activation energy. For example, a smoke explosion is a very violent combustion of unburned gases contained in the smoke created by a sudden fresh air input (oxidizer input). The interval in which an air/gas mix can burn is limited by the explosive limits of the air. This interval can be very small (kerosene) or large (acetylene).
  
  Water cannot be used on certain type of fires:
  
  BULLET::::- Fires where live electricity is present – as water conducts electricity it presents an electrocution hazard.
   This initial attack technique was not without its risks but proved very effective over the decades at keeping fires small, particularly in remote locations. As more powerful helicopters developed in the 1960s and 1970s crews were often "rappelled" into the fire or a helipad was cut. This aggressive direct attack technique was known as "dry firefighting" and as the name implied involves having limited or no access to water. It was hard physical work but an essential skill to fight remote forest fires. It was something that Commission staff were historically renowned and very few people, other than their families, were even aware that they might spend weeks away deep in the mountains. 
   In exploration wells, where flow rates are expected to be 10 tonnes of gas per day, testing is licensed by the Environment Agency to 30 days, extendable to 90 days. Enclosed burners are available that will ensure low levels of light pollution, little noise, and 99+% combustion and destruction of VOCs/BTEX, at around 800 C.
   Extinguishing underground coal fires, which sometimes exceed temperatures of 540 °C (1,000 °F), is both highly dangerous and very expensive.
  
  Near-surface coal seam fires are routinely extinguished in China following a standard method basically consisting of the following phases:
  
  BULLET::::- Smoothing the surface above the fire with heavy equipment to make it fit for traffic.
  
  BULLET::::- Drilling holes in the fire zone about 20 m apart down to the source of the fire, following a regular grid.
  
  BULLET::::- Injecting water or mud in the boreholes long term, usually 1 to 2 years.
   BULLET::::- 2010Pike River Mine disaster in New Zealand; a series of three explosions in the mine was followed by a fourth which set fire to the coal. 29 miners and contractors perished.
  
  BULLET::::- 2015Gunashli Platform No.10 fire broke out on the offshore oil and gas platform in the Azerbaijani section of the Caspian Sea on December 4; 12 confirmed deaths, 18 missing.
  
  Section::::Forest and countryside fires.
  
  BULLET::::- 1871The Great Michigan Fire, killed over 200 in Michigan
   Overseas forest and fire agencies, particularly the US Forest Service, the US Bureau of Land Management and State agencies such as the California Department of Forestry and Fire Protection (CalFire) as well as the Canadian Forest Service faced similar challenges and proved strong and willing partners in sharing knowledge, equipment and expertise over many decades.
  
  Section::::Major bushfires.
   Construction and renovation fires
  
  Fires are common in buildings under construction and renovation, and present particular difficulties to firefighters.
  
  During construction, buildings often do not have elements that would protect them from fire, such as walls and sprinkler systems. Poor water supplies and the accumulation of flammable materials also present risks. Works often require heat or even open flame, and these can set off fires that smoulder for hours before being noticed. For this reason, work sites may need 24-hour fire watches. 
  
  Builder's risk insurance may cover damage from such fires.
   During a typical year there are over 9,000 forest fires in Canada, burning an average of 2.5 million hectares (ha) or . The number of fires and area burned can vary dramatically from year to year. Average suppression costs are $500 million to $1 billion annually.
  