Master Sgt. Malcolm Mercado is hooked up to the oxygen system during a training mission over Dyess Air Force Base.
U.S. Air Force Master Sgt. Malcolm Mercado, a 40th Airlift Squadron loadmaster, is hooked up to the oxygen system prior to opening the ramp door on a C-130J Hercules aircraft flying at more than 10,000 feet during a training mission over Dyess Air Force Base, Texas, on Feb. 23, 2012.