DC-10 Air Tanker

The DC-10 Air Tanker is a series of American wide-body jet air tankers, which have been in service as an aerial firefighting unit since 2006. The aircraft, operated by the joint technical venture 10 Tanker Air Carrier, are converted wide body McDonnell Douglas DC-10 passenger jetliners, and are primarily used to fight wildfires, typically in rural areas. The turbofan-powered aircraft carry up to 12,000 US gallons (45,000 liters) of water or fire retardant in an exterior belly-mounted tank, the contents of which can be released in eight seconds. Two air tankers are currently in operation, with the call-signs Tanker 911 and Tanker 912. A third, Tanker 910, was retired in 2014.

The air tanker modification can be carried out to either a DC-10-10 or DC-10-30 series and involves the addition of an external tank and associated systems and support structure.

DC-10 Air TankerThe water or retardant is carried in three center-line belly tanks. The tanks have internal baffles to prevent fluid shift (and consequent shift in center of gravity) while in flight, and sit with a 15-inch (38 cm) ground clearance. All three tanks can be filled simultaneously on the ground in eight minutes. The retardant is gravity-fed out of the tanks, and the entire load can be dumped in eight seconds, although the actual drop rate is computer controlled by the flight crew in order to produce the desired retardant spread over the fire lines. The aircraft is capable of applying a line of retardant 300 ft (91 m) wide by 1 mile (1.6 km) long.

The external retardant tanks are designed to be filled from standard 3 inch cam-lock couplings. Utilizing one, two or three hoses, the tanks can be filled as quickly as base loading capabilities permit, typically 15–20 minutes. The tanks are vented to atmosphere by a vent system installed on top of each tank to allow sufficient air into and out of the tanks during retardant drops and filling. Accurate quantity gauges are part of the installation.

The number of drops it can make in a day is only limited by the time it takes to reload the aircraft with water/fire retardant and fuel, as well as its need for a proper landing field, which may well be a considerable distance from the fire. More details