Senior Airman Mitchell Lake conducts preflight checks on an F-15E Strike Eagle June 13, 2011, during the NORTHERN EDGE 2011 exercise at Eielson Air Force Base, Alaska. Airman Lake is a crew chief assigned to the 391st Aircraft Maintenance Unit at Mountain Home Air Force Base, Idaho. (U.S. Air Force photo/Staff Sgt. Christopher Boitz) Photo essay: Airmen participate in NORTHERN EDGE 2011 by Staff Sgt. Christopher Boitz 353th Fighter Wing Public Affairs 6/16/2011 - EIELSON AIR FORCE BASE, Alaska (AFNS)  -- Airmen participate in the NORTHERN EDGE 2011 exercise here June 13. NORTHERN EDGE is a joint training exercise designed to practice operations, techniques and procedures, and enhance interoperability among the services. View the slideshow.