DC-10 Air Tanker

The DC-10 Air Tanker is a series of 5 air tankers converted by American joint technical venture 10 Tanker Air Carrier, which have been in service as aerial firefighting aircraft since 2006. The aircraft are converted McDonnell Douglas DC-10-30s used to fight wildfires. The turbofan-powered aircraft carries up to 9,400 US gallons (35,583 liters) of water or fire retardant in an exterior belly-mounted tank, the contents of which can be released in eight seconds. Four air tankers are currently in operation, all DC-10-30 aircraft, with the call-signs Tanker 910, 911, 912 and 914. The original Tanker 910, a DC-10-10, was retired in 2014.

10 Tanker Air Carrier, a New Mexico-based company, began researching the development of Next Generation airtankers in 2002. Company personnel were assembled with an extensive history of heavy jet operations, modifications and ownership. After two years of research into aerial firefighting requirements and future direction, 10 Tanker selected the DC-10 type for development. A Supplemental Type Certificate (STC) from the US Federal Aviation Administration (FAA) for modifications of DC-10 aircraft to be used for the aerial dispersant of liquids was issued in March 2006. 10 Tanker then obtained a 14 CFR Part 137 Operating Certificate for aerial firefighting and Interagency Airtanker Board (IAB) approval for agency use.

The first converted aircraft, a McDonnell Douglas DC-10-10 registered as N450AX, was originally delivered as a civil passenger plane to National Airlines in 1975, and subsequently flew for Pan Am (as N69NA), American Airlines, Hawaiian Airlines (as N161AA) and Omni Air International.^{[citation needed]}

The conversion of the original airframe to a fire-fighting aircraft was a joint venture under the name of 10 Tanker Air Carrier between Cargo Conversions of San Carlos, California and Omni, with conversion work being performed by Victorville Aerospace at the Southern California Logistics Airport in Victorville, California.

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.

The 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 feet (91 m) wide by 1 mile (1.6 km) long.

The external retardant tanks are designed to be filled from standard 3-inch (76 mm) 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.^{[citation needed]}