When firefighters need a powerful punch in one swoop, they turn to a former passenger jet modified to deliver a knockout from the sky. The DC-10 Airtanker looks and sounds like a commercial airliner, but it's been converted to hold 50 tons of water or fire retardant, which can be dropped in a long line to prevent a fire from spreading.
Tanker 910, put into use by CAL FIRE in 2006, works like this. A lead plane flies ahead of the two-pilot tanker, helping to direct the drop. Using three separate external tanks, the DC-10 can drop up to 12,000 gallons of retardant in about eight seconds. It has a computerized system that allows the drop rate to be controlled from the cockpit. It's not as maneuverable as smaller firefighting aircraft, but can deliver much more fire retardant in one continuous line, helping firefighters with containment. The retardant is usually red in color so firefighters can recognize which areas have already been covered.
Once it drops the retardant, the tanker heads back for a refill, which takes about eight minutes.
Below are a few photos of the DC-10 in action at wildfires in California.