Aircrew prepares for takeoff
Maj. Brian Sealock, 20th Bomb Squadron, checks the seal on his flight equipment on Barksdale Air Force Base, La., March 13. Aircrew check the seals on their masks to make sure there are no oxygen leaks. A broken seal would make it hard for aircrew members to receive oxygen during an emergency. (U.S. Air Force photo/Airman 1st Class Benjamin Gonsier)(RELEASED)