As Californian emergency authorities continue to battle wildfires ravaging Los Angeles, many people have been left in awe of the capabilities and persistence of aerial water and fire-retardant bombardments being used to douse the flames.
The California Department of Forestry and Fire Protection — known in short as CAL Fire — says it "boasts the largest civil aerial firefighting fleet worldwide" and it has been deployed in the hope of extinguishing the blazes.
Since the turn of the new year, more than 101 wildfires have broken out across California, burning through more than 15,000 hectares of land.
In Los Angeles, four major wildfires continue to challenge firefighters: the Palisades fire — which has become the most destructive fire in the city's history and torn through almost 10,000 hectares — the Eaton Fire, the Kenneth Fire and the Hurst Fire.
With the front lines rapidly changing, firefighting aircraft have been a consistent sight in the Los Angeles skies since the blazes began on Tuesday, dumping more than 56,700 litres of fire retardant and up to 240,000 litres of water in a single day.
Which aircraft are being used to fire the LA fires?
CAL Fire operates a firefighting aviation program that relies on five different types of aircraft to extinguish wildfires or keep them burning at contained lows.
"These aircraft, highly skilled pilots, and aviation support staff are strategically located throughout California at our 14 air tanker bases, 10 CAL FIRE helitack bases and one CAL FIRE/San Diego County Sheriff helitack base," according to the CAL Fire website.
"Aircraft can reach the most remote State Responsibility Area (SRA) fires in approximately 20 minutes, with the goal of keeping 95% of fires at 10 acres (four hectares) or less."
The organisation's fleet currently consists of 67 different aircraft, including helicopters and air tactical planes.
The two types of helicopters in rotation are the UH-1H chopper, known as the "Super Huey", and the Sikorsky S70i, which is nicknamed the "Hawk".
The Super Huey is crewed by up to 11 emergency personnel and can pick up and dump 1,226 litres of water or fire retardant during bucket-bombing operations or up to 227 litres using a pilot-controlled fixed tank.
The Hawk only has a fixed tank, but can drop up to 3,785 litres of water or firefighting foam onto a blaze.
For major firefighting responses, CAL Fire uses its tactical planes — the S-2T and C-130H air tankers — for "rapid initial attack delivery of fire retardant on wildland fires", carrying up to 1,200 litres and more than 15,000 litres respectively.
CAL Fire's overall fire response during emergency situations is overseen by another pilot and observer based in the air in an OV-10 air tactical plane.
The Californian aerial bombardment has also been bolstered this week by extra federal resources announced on Thursday by US President Joe Biden, including three additional CL-415 water-bombing planes and nine helicopters which have joined the five air tankers and 10 choppers already fighting the fires.
The CL-415 has already developed an online following under the nickname "Super Scooper" due to its visually impressive water-bombing capabilities and precision in dumping sea water on specific fires.
The Canadian not-for-profit Societe De Protection Des Forets (SOPFEU) also delivered its own CL-415 to California to help in the emergency response.
Quebec sends two of the aircraft to the state each year under a three-decade-old arrangement between their governments, according to CNN.
One of the Super Scooper fleet, Quebec 1, was grounded on Thursday after it collided with a civilian drone and sustained wing damage, but it is expected to be repaired and back in circulation by Monday, according to LA County Fire Chief Anthony C Marrone.
What is the retardant used to fight fires?
While the aerial bombardment over the fires in Los Angeles has mostly involved aircraft picking up seawater out of the Pacific Ocean, bright pink and red retardant has also been used to coat flames on the ground.
An information document published online by CAL Fire said the retardant was made up of 88 per cent water and 12 per cent ammonium phosphate, which is commonly used in fertilisers.
The substance also includes gum thickeners to help the retardant stick to burning plants and trees, and red or pink colouring dye so the pilots can see where drops land from above.
The CAL Fire document says the retardant coats the ground and acts as a fuel break, with the chemicals in the substance reducing the chance of vegetation combusting when flames approach.
Firefighters also say the retardant is not hazardous for humans, animals or plants but can cause minor skin irritation due to the ammonium.
How could the LA fires impact Australia?
Australia and the United States signed a bilateral agreement in 2017 that determined the sharing of emergency personnel resources whenever a disaster struck.
Part of that agreement is a leasing deal for Australian firefighting organisations to be able to access water-bombing aircraft typically stationed in California.
Leigh Hills, the national president of the United Firefighters Union of Australia, told the ABC that this year's Los Angeles wildfires showed that the US fire season was lasting longer into the country's winter while Australia's bushfires season was starting earlier in the summer.
He said the overlap could pose a significant issue for Australian firefighting capabilities in the future.
"Certainly it is a concern. It's something I know various political parties on the national level are looking at in regards to shoring up and having our own assets," Mr Hills said.
"We may not be able to rely on those agreements in the future, or we may have an agreement but those assets may be drawn back to the US.
"Rather than release [the aircraft] in October, November, if they know that they're going to have fires through until January, they wouldn't be releasing them until much later.
"Firefighters and those in the industry have been warning about this for certainly the last eight to 10 years."
Mr Hills said if Australia's firefighters were to lose Californian resources prior to or during a bushfires disaster, it would drastically reduce the speed and efficacy of local emergency responses.
"The whole idea of using aircraft is early action," he said.
"You can get an aircraft in the air [and] get it 100 to 200 kilometres away from wherever it is located very, very quickly, whereas it takes a long time to get ground assets to a particular location.
"No state or territory could do it without some sort of federal system in place … Every political party makes a commitment to a national system for aircraft and assets."
