Four U.S. Air Force C-130 aircraft are helping local authorities fight the raging wildfires in Arizona by flying above impacted areas and dropping thousands of gallons of fire retardant to contain the spread of flames, service officials report.
"They are pushing the aircraft to its maximum performance," said Ann Skarban, a spokeswoman for the 302nd Air Lift Wing. "They are flying slow, low and heavy. They are working to draw lines of containment to break up or stop the fire."
The C-130s typically drop flame retardant from altitudes of 150-feet above the ground, traveling at speeds of 120 knots, said Dave Carey, Chief Flight Engineer, 731 Air Lift Squadron. The retardant is dropped along the perimeter or outer-contours of an expanding fire in support of fire-fighters on the ground in order to stop or contain the spread of the flames, Carey explained.
The C-130 airplanes, which were directed by the U.S. Forest service to head toward fire-damaged areas in Arizona from Colorado Springs, Colo., are configured with special fire-fighting technology called Modular Airborne Fire Fighting Systems, or MAFFS, Skarban said.
The C-130s are operating from Phoenix Mesa-Gateway Airport, said Lt. Col. Robert Carver, a spokesman for 145th Airlift Wing.
"The planes are able to lay down a line of fire retardant and check the fire, stopping it in its tracks. The teamwork with the crews on the ground, local first responders, and the U.S. Forest Service is amazing as it helps to establish where the best place is to drop the retardant," said Carver.
Military aircrews can discharge 3,000 gallons of water or fire retardant from the MAFFS modules along the leading edge of a forest fire in less than five seconds and cover an area a quarter of a mile long by 100 feet wide, according to a statement from U.S. Northern Command. Two of the aircraft helping the Arizona effort are from the 302nd Airlift Wing located at Peterson Air Force Base, Colo., and two more are from the 146th Airlift Wing, California Air National Guard, based at Channel Islands Air National Guard Station.
The amount of retardant, a concentrated liquid substance which is diluted with water before being released from the plane, varies depending upon a range of factors such as air pressure, terrain, altitude and weight, said Carey.
For instance, higher altitudes and hotter temperatures result in decreased air pressure, making it more difficult to fly and maneuver an aircraft, especially C-130s loaded with thousands of gallons of fuel, Carey added.
"We keep track of the volume that we load on because we can't always load a full tank based on the altitude and how hot it is. We are required to meet climb restrictions if we lose an engine -- so we need to be able to climb away from the terrain - to do that we sometimes need to limited how much retardant can go on the aircraft," he said.
The pressure and volume of the retardant, controlled by a valve and an on-board computer on the plane, also varies depending upon the terrain and vegetation of the fire affected area, Carey explained.
The C-130 planes typically enter a fire traffic area following about 1,000-feet behind a smaller lead plane – such as a King Air -- which provides a start point, stop point and pressure setting for the retardant, he said.
"If there is a lot of vegetation, they will want more pressure to shoot it down inside of there. If it is prairie fire or lava-field fire, they will want a lower pressure setting. With a high pressure setting it comes out quicker," Carey said.
Once the load is discharged, ground crews at a MAFFS tanker base can refill the modules in less than 12 minutes, Air Force Reserve officials added. Four additional MAFFS-capable C-130s are operated by Air National Guard units in North Carolina and Wyoming and can be called on if needed.