LOXing the Fleet: Always a Cold Day Published Feb. 7, 2012 By TSgt. Dan Heaton 127th Wing Public Affairs SELFRIDGE AIR NATIONAL GUARD BASE, Mich. -- Three hundred degrees below zero. Some days are much, much colder than others on the flight line at Selfridge Air National Guard Base. Take LOX servicing day, for example. LOX - shorthand for liquid oxygen - is used by the Air Force to provide breathing oxygen for pilots in its fighter aircraft. When oxygen gets down below 300 degrees or so below zero, it becomes a liquid and takes up considerably less space than does its more common gas form. The Air Force, and other operators of high-performance aircraft, use liquid oxygen on aircraft so that they are able to provide a substantial supply of oxygen to the aircraft's pilot and crew without taking up a lot of space and adding extra weight with large, bulky air tanks. Wearing doubled gloves, a leather apron and a full face mask, Airman 1st Class Zak Skelton needs only a few minutes per aircraft to ensure that each of the A-10 Thunderbolt II's on the flight line at Selfridge are topped off with LOX and ready for the next mission. Skelton, and other crew chiefs with the 127th Aircraft Maintenance Squadron at Selfridge, generally refill the aircraft LOX tank in each A-10 once per week, or more often if needed. The crew chiefs refer to the process as "LOXing the fleet." Depending on the duration of the flight and the particular pilot who flies in the aircraft, each A-10 can fly 2-3 sorties before it needs to be refilled with LOX again, said TSgt. Juan Lopez, who has been working as an A-10 crew chief in the Michigan Air National Guard for about 16 years, first in Battle Creek and for the past couple of years at Selfridge. He has more than 34 years of total service in the military. "Every pilot is a little different," Lopez said. "Some use more air than others. And, naturally it depends on how long they fly." Each A-10 can hold about five liters of LOX. Because liquid oxygen boils at approximately 298 degrees below zero, handling it requires special precautions, such as the gloves and face shield Skelton put on prior to re-filling the aircraft. A cloud of escaping cold, white vapor is a regular feature of LOX operations. Skelton also pointed out that since LOX is pure oxygen, it is highly flammable, so safety is key to working with it. Skelton recently completed his initial technical school as a crew chief at Sheppard Air Force Base in Texas, spending almost six months in school. That was followed by about a month of hands-on training at Davis-Monthan Air Force Base in Arizona. He's been a member of the Michigan Air National Guard for about two years. In addition to his duties and training as an A-10 crew chief in the Air National Guard, Skelton is a student in the aircraft technology program at Lansing Community College. He said he hopes to work in the civilian aircraft industry after he completes his college degree, while continuing to serve in the Michigan Air National Guard.