Complex sentence: The F-106 Delta Dart, considered by many the finest all-weather interceptor ever built, was the primary air defense interceptor aircraft for the US Air Force during the 1970s and early 1980s.
Split into simpler sentences: The F-106 Delta Dart remained, as it was considered by many as being the finest all-weather interceptor ever built. It was the primary air defense interceptor aircraft for the US Air Force during the 1970s through the early 1980s.