Brig. Gen. Mark Barrett, the commander of the 1st Fighter Wing at Langley Air Force Base, Va., will head the board that will probe the July 21 crash of a B-52 bomber. The plane went down just before arriving at Anderson Air Force Base, Guam, from its home at Barksdale Air Force Base, La., killing all six crewmembers. When the panel finishes, it will present the findings to Gen. John Corley, the chief of Air Combat Command.