Sergeant Christopher Martinez, the operations chief serving with the fire direction center with 2nd Battalion, 11th Marine Regiment, and a native of Orange County, Calif., sends a fire mission to the gunline during Exercise Desert Scimitar, a combined-arms, live-fire training exercise here, May 2, 2013. The FDC receives target data from forward observers and computes it into firing commands for the gunline. The data has to compensate for wind speed, air pressure, temperature, humidity and other weather conditions that will affect the round during its flight.