Complex sentence: When they take off in a Stinson 108 light aircraft, Cal and Ruth watch as the facility and all its inhabitants are incinerated, and their aircraft is drawn up by a bright beam into a flying saucer.
Split into simpler sentences: When they take off in a Stinson 108 light aircraft, Cal and Ruth watch as the facility and all its inhabitants are incinerated. Then their aircraft is drawn up by a bright beam into a flying saucer.