More than 60 volunteers from Nellis Air Force Base wait to receive simulated medical care during the 2012 Triennial Emergency Preparedness Exercise at McCarran International Airport Oct. 24, 2012, in Las Vegas, Nev. The exercise is conducted every three years by the Clark County Department of Aviation to maintain safety and emergency response readiness in order to maintain the Federal Aviation Administration certification. (U.S. Air Force photo by Airman 1st Class Jason Couillard)