This scarlet splash is fire retardant: a blend of water, guar gum and a salt called ammonium polyphosphate. Washington state aerial firefighting company Aero-Flite uses the colourful cargo to prevent wildfires from destroying forests.
It clings to vegetation around the edge of a fire, so when the trees burn, they produce water instead of flammable gases to help stall the progression of the blaze.
Mike Lynn, Aero-Flite's head of flight operations, says the red colour - obtained by adding iron oxide – makes it clear to pilots which areas have already been covered: "It shows up against the green canopy of the trees." The liquid - seen above being dropped on a Californian forest in 2014 – is harmless for terrestrial life, unless ingested, although it is toxic to fish.
Aero-Flite's fleet comprises five converted passenger jets, each holding up to 12,500 litres of retardant. To spread it properly, the specially trained pilots must not fly higher than 53 metres from the ground, and move steadily at 120 knots (222kph).
"The secret is not going too fast, as the retardant has to rain down," says Lynn, 63. "If it has too much momentum, it can knock over trees."
This article was originally published by WIRED UK
