Fire managers are requesting more aircraft to help fight the High Park and Springer fires burning in Colorado.
Seven "heavy" air tankers were working in Colorado as of Monday morning, representing more than half of the national fleet. The center filed requests for three more.
Heavy tankers carry about 3,000 gallons of fire retardant and are able to help slow fires over large areas.
9NEWS has received several concerned emails wondering why National Guard C-130 cargo planes are not being used.
Eight such planes are standing by across the country, including a pair in Colorado and another in Wyoming.
A special retardant-spraying unit can be slid into the cargo area to convert the military planes into heavy air tankers.
Federal officials say these are meant to be a last resort when the national fleet is completely tapped out.
"Right now, nationally we're not at that level," Steve Segin, with the RMACC, said.
Once that threshold is met, the C-130's take 36 hours to be converted and dispatched and must be activated for a minimum of 30 days due to military logistics, Segin said.
Colorado already has dozens of helicopters battling flames. The most powerful of which can hover close to the surface of lakes and ponds and suck up 2,600 gallons of water through a snorkel in less than one minute.
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