Senior Airman Eric Humphrey, an 82nd Expeditionary Rescue Squadron pararescueman, throws a colored smoke grenade to mark his team’s position during a training scenario in the Grand Bara Desert, Djibouti, October 21, 2011. Using a colored smoke signal is one way pararescuemen designate their position to an air evacuation team. (US Air Force photo/Staff Sgt. Renae Saylock)