Complex sentence: From 1997 to 2001 he was Deputy Branch Chief of the GN&C branch and in 1999 he led the Space Shuttle Program office and the Abort Improvement Team that was chartered with closing all ascent of loss of vehicle/loss of crew abort scenarios.
Split into simpler sentences: From 1997 to 2001 he was Deputy Branch Chief of the GN&C branch. In 1999 he led the Space Shuttle Program office and the Abort Improvement Team that was chartered with closing all ascent of loss of vehicle/loss of crew abort scenarios.