Complex sentence: During 1958--59, USAF navigator training training operations were closed out at Ellington and consolidated at Mather AFB, California and James Connally AFB, Texas, followed by a second consolidation to Mather AFB as the sole USAF navigator training location in the early 1960s.
Split into simpler sentences: During 1958--59, USAF navigator training operations were eliminated at Ellington and consolidated at Mather AFB, California and James Connally AFB, Texas. This was followed by a second consolidation to Mather AFB as the sole USAF navigator training location in the early 1960s.